**Table 3.**

*Parameters of static load of wooden ceiling supporting members at the standard fire temperature.*

**109**

equipment, chimneys, etc.

working hours.

*A Case Study on the Fire Safety in Historic Buildings in Slovakia*

**Densities in mega-joules per square meter Pn conversion** 

**<sup>730802</sup> Occupancy Mean** 

**Percent fractile\***

**80 90 95** Dwellings 780 870 920 970 52 40 Hospitals 230 350 440 520 21 20 Hotel rooms 310 400 460 510 24 30 Offices 420 570 670 760 34 40 Shops 600 900 1100 1300 54 90 Museums 300 470 590 720 28 60 Libraries 1500 2250 2550 --- 134 120 Schools 285 360 410 450 22 25

**from EK (16,75) 80% fractile**

**Pn value from Table A1 in STN** 

staircases and their location in relation to the center of gravity of evacuated persons, ventilation of staircases and disposition possibilities of their fire separation, evacuate conditions for person and historic articles depending on the building's functional use in fire as well as the accessibility and safety of staircases for firefighters. It also assesses the possibilities of fire spreading in the building's open spaces, e.g. central representative staircases, open galleries, internal atriums, unsealed crawl spaces in ceilings, etc. The analysis determines the construction and division of the building into smaller units—fire compartments, location of fire doors and

*Comparison of the fire load density values in different occupancies according to the data given in EN 1991-1-2* 

*.*

*The percent fractile is the value that is not exceeded in that percent of the rooms or occupancies.*

*Analysis of the current operational solution in terms of fire prevention*—includes an assessment of the building's functional use considering the accidental fire load with regard to the fire resistance of the existing load-bearing structures and the number of persons in terms of the capacity of existing evacuation routes. It also contains assessment of internal organizational measures that should minimize the causes of fire such as regular inspections of electrical installations and appliances, technical

*Analysis of the current fire detection system*—includes an assessment of the function and location of the automatic fire detection system. If there is no such system installed in the building (this is the common situation in historic buildings in Slovakia), it is necessary to verify the organizational measures ensuring fire detection, that is to ask authorized employees to be helpful and use their senses. This includes regular inspections in the building by its guard. If there is no guard in the smaller buildings, the inspection is done by authorized employees at the end of

*Analysis of the fire equipment availability in case of fire*—finds out the location of portable fire extinguishers, their capacity and extinguishing agent. It analyzes the availability of internal firefighting water and wall fire hydrants as well as their position and functionality. It also verifies the location, capacity and functionality of external firefighting water sources, that is external hydrants, water tanks and natural water sources that can be used by fire brigades. It analyzes organizational measures related to fire extinguishing such as staff training, firefighting documentation, identification of emergency routes and access roads. After determining the

the way of their closing and risk of fire spreading to adjacent buildings.

*DOI: http://dx.doi.org/10.5772/intechopen.91241*

**(MJ/m2 )**

*Conversion factors: 1 MJ* ≈ *0.948 BTU, 1 m2* ≈ *10.8 ft2*

*\**

**Table 4.**

*and Table A1 STN 730802.*

*A Case Study on the Fire Safety in Historic Buildings in Slovakia DOI: http://dx.doi.org/10.5772/intechopen.91241*


*Conversion factors: 1 MJ* ≈ *0.948 BTU, 1 m2* ≈ *10.8 ft2 .*

*\* The percent fractile is the value that is not exceeded in that percent of the rooms or occupancies.*

#### **Table 4.**

*Fire Safety and Management Awareness*

**108**

**No**

1 2 3

Column

d = 2302 *1Positive sign (+) means tensile force; negative sign (−) means compression force.*

*2The average column diameter at its narrowest spot.*

**Table 3.** *Parameters of static load of wooden ceiling supporting members at the standard fire temperature.*

0.07

0.78

33.30

0.142

1.676

1.502

0.16 < 1.0 meets

Roof

300

270

8.78

−0.10

9.05

5.118

0.050

0.180

0.23 < 1.0 meets

girder

Ceiling

200

250

3.81

0.38

0.32

3.454

0.544

0.011

0.15 < 1.0 meets

beam

**Member**

**b [mm]**

**h [mm]**

**My,Ed,fi**

**Mz,Ed.fi**

**NEd,fi**

**σm,y,d,fi**

**σm,z,d,fi**

**σc(t),0,d,fi**

**Assessment bend**

**(bend + tension)**

 **+**

**pressure** 

**[MPa]**

**[MPa]**

**[MPa]**

**[kN]**

**R30**

**[kNm]**

**[kN]**

*Comparison of the fire load density values in different occupancies according to the data given in EN 1991-1-2 and Table A1 STN 730802.*

staircases and their location in relation to the center of gravity of evacuated persons, ventilation of staircases and disposition possibilities of their fire separation, evacuate conditions for person and historic articles depending on the building's functional use in fire as well as the accessibility and safety of staircases for firefighters. It also assesses the possibilities of fire spreading in the building's open spaces, e.g. central representative staircases, open galleries, internal atriums, unsealed crawl spaces in ceilings, etc. The analysis determines the construction and division of the building into smaller units—fire compartments, location of fire doors and the way of their closing and risk of fire spreading to adjacent buildings.

*Analysis of the current operational solution in terms of fire prevention*—includes an assessment of the building's functional use considering the accidental fire load with regard to the fire resistance of the existing load-bearing structures and the number of persons in terms of the capacity of existing evacuation routes. It also contains assessment of internal organizational measures that should minimize the causes of fire such as regular inspections of electrical installations and appliances, technical equipment, chimneys, etc.

*Analysis of the current fire detection system*—includes an assessment of the function and location of the automatic fire detection system. If there is no such system installed in the building (this is the common situation in historic buildings in Slovakia), it is necessary to verify the organizational measures ensuring fire detection, that is to ask authorized employees to be helpful and use their senses. This includes regular inspections in the building by its guard. If there is no guard in the smaller buildings, the inspection is done by authorized employees at the end of working hours.

*Analysis of the fire equipment availability in case of fire*—finds out the location of portable fire extinguishers, their capacity and extinguishing agent. It analyzes the availability of internal firefighting water and wall fire hydrants as well as their position and functionality. It also verifies the location, capacity and functionality of external firefighting water sources, that is external hydrants, water tanks and natural water sources that can be used by fire brigades. It analyzes organizational measures related to fire extinguishing such as staff training, firefighting documentation, identification of emergency routes and access roads. After determining the


#### **Table 5.**

**111**

*A Case Study on the Fire Safety in Historic Buildings in Slovakia*

firefighting partitions at the required time.

• Enable safe evacuation of persons from the building.

• Enable effective and safe intervention of fire brigades.

reducing the open layouts going through more floors

sary to reduce the building's occupancy

• Detection of the fire risk resulting from the building's operation

roofs and burning other structures.

to be changed contains mostly:

protection

areas

fire extinguishers

extinguishing equipment.

**5.3 Fire compartmentation**

current fire safety measures in the building, the restoration or functional change is optimized in such a way that the planned alternation would not reduce the current

The fire safety in buildings is generally a combination of passive and active measures ensuring the following points for each fire section during the fire:

• Retain the carrying capacity and stability of load-bearing structures and

• Reduce the development and spread of fire and smoke within the building.

• Reduce the spread of fire toward the surrounding buildings through windows,

The building solution for a historic building whose original function is planned

• Fire compartmentation of the building excluding concentrated fire load and

• Fire resistance assessment of existing fire separation structures consider

ing the fire risk, fire height and combustibility of load-bearing and fire separation structures including the possible solution for their additional fire

• Construction of protected emergency routes if it is possible; if not, it is neces

• Ensuring the accessibility of sufficient source of firefighting water and hand

• Construction of the safe intervention routes including access roads and boarding

If there are some barriers on the access roads to the building such as castle hills or impassable entrance gates, it is necessary to determine a set of construction and fire-technical measures using active elements of fire protection, e.g. stationary fire

If it is possible in terms of building's operation, it should always be divided into several smaller fire compartments to minimize fire damage and increase the occu

pants' safety during evacuation and fire intervention. If there are no complications




*DOI: http://dx.doi.org/10.5772/intechopen.91241*

building's fire safety.

**5.2 Fire safety design**

*Optimization of functional changes in historic buildings in terms of fire protection requirements for original structural elements according to STN 73 0802/2010 and 2015.* current fire safety measures in the building, the restoration or functional change is optimized in such a way that the planned alternation would not reduce the current building's fire safety.

### **5.2 Fire safety design**

*Fire Safety and Management Awareness*

30/15

**110**

**Original functional use of buildings,** 

**Functional usability**

**Fire hazard**

**DFSB** 

**Requirements for fire-separating structures in the composite** 

**construction unit on the first/last floor**

**STN** 

**730802**

**Walls**

**REI**

**REI**

**REI**

**EI, EW**

**Ceilings**

**Roof**

**Fire dampers**

**a**

**pv (kg/m2**

**)**

**fire height**

Churches, fh = 0 m

Cloister premises, fh ≤ 9 m

Galleries Museums Concert halls

Libraries Coffee bars Accommodation, apartment

buildings

Administration

Education

Gallery Museums

Hotels Galleries, museums

Hotels Club spaces Kindergartens Hotels, apartment buildings

Administration

1.0 1.0 *fh—building's fire height; pv—calculated fire load in kg/m2 (the average fire load value of the entire fire compartment); a—coefficient of combustible materials (burning rate) (Table A1 STN 730802);* 

*b—coefficient of ventilation efficiency (ventilation rate); REI—time in minutes (minimal time during which the criteria for load, stability and integrity of thermal insulation are met); EI—time in minutes* 

*(minimal time during which the criteria for integrity of thermal insulation are met); EW—time in minutes (minimal time during which the criteria for insulation integrity guided by radiation are met);* 

*DFSB—degree of fire safety of building structures (expresses the summary of technical requirements for fire-separating structures).*

*Optimization of functional changes in historic buildings in terms of fire protection requirements for original* 

*structural elements according to STN 73 0802/2010 and 2015.*

**Table 5.**

40

III.

60/45

60/45

45

45/30

30

III.

60/45

60/45

45

45/30

Castles, mansions, fh ≤ 12 m

Townhouses, villas, palaces, fh ≤ 12 m

1.0 0.9 1.2 1.1 1.0 1.1 1.0 1.1 0.9

32

III.

60/45

60/45

15

45/30

33

III.

60/45

60/45

45

45/30

30

III.

60/45

60/45

45

45/30

66

III.

60/45

60/45

45

45/30

30

III.

60/45

60/45

45

45/30

66

III.

60/45

60/45

45

45/30

18

II.

45/30

45/30

30

30/30

22

II.

45/30

45/30

30

30/30

40

III.

60/45

60/45

45

45/30

1.2 1.1 1.1 0.7 1.2 1.0

40

III.

60/45

60/45

45

45/30

37

III.

60/45

60/45

45

45/30

84

IV.

90/60

90/60

60

60/D1

33

I.

30/15

30/15

15

30/15

66

I.

30/15

30/15

15

18

I.

30/15

30/15

15

30/15

The fire safety in buildings is generally a combination of passive and active measures ensuring the following points for each fire section during the fire:


The building solution for a historic building whose original function is planned to be changed contains mostly:


If there are some barriers on the access roads to the building such as castle hills or impassable entrance gates, it is necessary to determine a set of construction and fire-technical measures using active elements of fire protection, e.g. stationary fire extinguishing equipment.

#### **5.3 Fire compartmentation**

If it is possible in terms of building's operation, it should always be divided into several smaller fire compartments to minimize fire damage and increase the occupants' safety during evacuation and fire intervention. If there are no complications during the fire intervention and the fire brigade arrive in the first phase of fire, then there is minor material damage found usually in the fire-affected part of the building.

The separate fire compartments always include emergency routes, gathering areas, rooms with a high fire load, warehouses and technical rooms.

The fire separation of an existing staircase from adjacent spaces with vertical fire load divides the building into more floors that are simultaneously fire compartments. They reduce the spread of thermal radiation and smoke within the building and relatively safe evacuation [18]. The staircases are separate fire compartments without fire risk; their layout, ventilation and air exchange frequency depend on the time required for evacuation of persons.

The separate fire compartments should be all spaces with installations—airconditioning engine rooms, boiler rooms, switch rooms, installation shafts as well as storage areas, deposits, etc.

If the spaces are modified for housing, accommodation, hospital or meeting, they must be divided into the fire compartments. Each dwelling unit must be a separate fire compartment; the same is valid for bed sections in hospital, hotel rooms or meeting rooms and museums, exhibition halls, theaters, etc. Any room or fire compartment containing more than 200 people is considered to be a meeting room. There are no exceptions allowed, and it is always necessary to reach an agreement between the fire safety requirements and building conservation.

The multistory fire sections require higher fire resistance of building structures than single-story ones, as the fire load is concentrated on the first floor. If fire occurs, it is supposed that the entire building will burn at the same time. The building structures are required to withstand thermal stress without breaking their stability and integrity throughout the fire of the entire building, that is longer than the single-story fire compartment. Finance that are saved by reducing the fireseparating structures such as doors, ceilings, etc. are usually used to ensure the fire resistance of the existing structures if they are composite and combustible. Such solutions absolutely do not respect property protection and safety of persons in the building. If fire damage is to be minimized, the building must be divided into fire compartments. The maximum area of fire compartments depends on the combustibility of the structure, number of floors and coefficient of combustible substances.

#### **5.4 Fire risk**

The fire safety solution in historic buildings whose original function is changed depends on the extent of construction modifications and planned functional use of the original spaces. If the functional use of historic buildings is planned to be changed, the real fire risk related to the planned operation should be taken into account. The fire risk is specified for each fire compartment. Its value depends on the combustibility and heating capacity of materials used in particular spaces depending on their functional use, coefficient of combustible substances, ventilation and active fire safety equipment. It is calculated from the relation:

$$\text{qf}, \text{d} = \text{qf}, \text{k.m.} \text{\"\textdegree \textquotesingle}{\text{qf}} \text{\"\textquotesingle}{\text{\"\textquotesingle}{\text{\"\textquotesingle}{\textquotesingle}{\text{\"\textquotesingle}{\textquotesingle}{\textquotesingle}{\text{\"\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}{\textquotesingle}$$

**113**

*A Case Study on the Fire Safety in Historic Buildings in Slovakia*

1991-1-2 and comparison with parameters STN 920201-1).

qf,k = \_1

Fire load can be determined by a calculation from relation (5) or from statistical values; examples for selected types of operations are given in **Table 1** (source EN

∞ (*i*. *mi*. *Hui*. *Mi*) (5)

Fire load Q in a fire compartment is defined as the total energy that can be released in fire occurrence. One part of the total energy will be used to heat the space (walls and internal gas); the rest of the energy will be released through openings—building elements such as wall and ceiling linings. The building content such as furniture is the fire load. Fire load Q divided by the floor area gives the fire load

density qf. Typical fire load density in EC 1 is defined by the equation [10]:

*Af* · ∑*<sup>i</sup>*

where Mi is the mass of material i [kg]; Hui is the net heating value of material i [MJ/kg]; mi is the factor describing combustible properties of material i; Ψi is the factor assessing protected fire load of material i; and Af is the floor area of the fire

HuiMi represents the total amount of energy that is contained in material i and released if combustion process is complete. Factor "m" is a non-dimensional factor between 0 and 1 representing combustion efficiency: m = 1 corresponds to complete combustion, and m = 0 if materials do not contribute to fire. The value of m = 0.8 is suggested for standard materials; the value of Hu = 17.5 MJ/kg is sug-

Common building designs supposing the use of similar material quantities with the same heating capacity in installations can work with the statistical value of typical fire load density, as defined in EN 1991-1-2; if the designs are done in Slovakia, they follow Table A1 STN 730802. The value of accidental fire load stated in this standard is the weight of wood in kg calculated per unit of the floor area of

The functional change of the original spaces changes the fire risk and number of persons. The change of building's fire height, e.g. by roof extension, changes the original building's fire height, fire protection requirements and evacuation plans. An increasing number of persons in the building change the requirements for the capacity and ventilation of emergency routes as well as the fire resistance of fire separation structures. Therefore, it is very important for the investment plan (as for space function and useful floor area extension) to be optimized in such a way that the original boundary conditions would not be changed fundamentally in terms of fire safety and would not require additional significant alternations to the building

The fire resistance requirements for building constructions specified in STN 73 0802 are directly dependent on calculated fire load, building's fire height and combustibility of constructions used in a building. It is optimal to prefer opera-

containing mostly composite construction systems was changed. This value considers the operational fire load, surface finishes, effect of ventilation and fire-technical equipment. Classrooms, hotel rooms, coffee bars, offices or galleries are classified as

pv = (pn + ps) . a . b . c (kg/ m<sup>2</sup>

spaces with medium fire load (medium fire development) (see **Table 5**).

Calculated fire load is determined by the relations:

all combustible materials in this area. **Table 4** shows the data comparison.

, whose heating capacity is the same as heating capacity of

if the function of restored buildings

) (6)

*DOI: http://dx.doi.org/10.5772/intechopen.91241*

**5.5 Fire load**

compartment [m2

fire compartment in m2

].

structures affecting their historic value.

tions with a calculated fire load up to 50 kg/m<sup>2</sup>

gested for wood, resulting in 14 MJ/kg for (m.Hu).

where qf, k is the fire load density per floor area unit MJ/m2 ; m is the burning rate coefficient; δq1 is the fire danger; δq2 is the fire danger; and δqn is the function of active fire-protective measures (δqn1–δqn2 automatic fire extinguishers, δqn3– δqn5 automatic fire alarms).

The fire load density expresses the probable fire intensity in the fire compartment or its part.

#### **5.5 Fire load**

*Fire Safety and Management Awareness*

the time required for evacuation of persons.

as storage areas, deposits, etc.

during the fire intervention and the fire brigade arrive in the first phase of fire, then there is minor material damage found usually in the fire-affected part of the building. The separate fire compartments always include emergency routes, gathering

The fire separation of an existing staircase from adjacent spaces with vertical fire load divides the building into more floors that are simultaneously fire compartments. They reduce the spread of thermal radiation and smoke within the building and relatively safe evacuation [18]. The staircases are separate fire compartments without fire risk; their layout, ventilation and air exchange frequency depend on

The separate fire compartments should be all spaces with installations—airconditioning engine rooms, boiler rooms, switch rooms, installation shafts as well

If the spaces are modified for housing, accommodation, hospital or meeting, they must be divided into the fire compartments. Each dwelling unit must be a separate fire compartment; the same is valid for bed sections in hospital, hotel rooms or meeting rooms and museums, exhibition halls, theaters, etc. Any room or fire compartment containing more than 200 people is considered to be a meeting room. There are no exceptions allowed, and it is always necessary to reach an agree-

The multistory fire sections require higher fire resistance of building structures than single-story ones, as the fire load is concentrated on the first floor. If fire occurs, it is supposed that the entire building will burn at the same time. The building structures are required to withstand thermal stress without breaking their stability and integrity throughout the fire of the entire building, that is longer than the single-story fire compartment. Finance that are saved by reducing the fireseparating structures such as doors, ceilings, etc. are usually used to ensure the fire resistance of the existing structures if they are composite and combustible. Such solutions absolutely do not respect property protection and safety of persons in the building. If fire damage is to be minimized, the building must be divided into fire compartments. The maximum area of fire compartments depends on the combustibility of the structure, number of floors and coefficient of combustible substances.

The fire safety solution in historic buildings whose original function is changed depends on the extent of construction modifications and planned functional use of the original spaces. If the functional use of historic buildings is planned to be changed, the real fire risk related to the planned operation should be taken into account. The fire risk is specified for each fire compartment. Its value depends on the combustibility and heating capacity of materials used in particular spaces depending on their functional use, coefficient of combustible substances, ventila-

rate coefficient; δq1 is the fire danger; δq2 is the fire danger; and δqn is the function of active fire-protective measures (δqn1–δqn2 automatic fire extinguishers, δqn3–

The fire load density expresses the probable fire intensity in the fire compart-

qf,d = qf,k . m . δq1 δq2 δn MJ/ m<sup>2</sup> (4)

; m is the burning

tion and active fire safety equipment. It is calculated from the relation:

where qf, k is the fire load density per floor area unit MJ/m2

ment between the fire safety requirements and building conservation.

areas, rooms with a high fire load, warehouses and technical rooms.

**112**

δqn5 automatic fire alarms).

ment or its part.

**5.4 Fire risk**

Fire load can be determined by a calculation from relation (5) or from statistical values; examples for selected types of operations are given in **Table 1** (source EN 1991-1-2 and comparison with parameters STN 920201-1).

Fire load Q in a fire compartment is defined as the total energy that can be released in fire occurrence. One part of the total energy will be used to heat the space (walls and internal gas); the rest of the energy will be released through openings—building elements such as wall and ceiling linings. The building content such as furniture is the fire load. Fire load Q divided by the floor area gives the fire load density qf. Typical fire load density in EC 1 is defined by the equation [10]:

$$\text{qf.}\,\text{k} = \frac{1}{Af} \cdot \sum\_{i}^{\circ\circ} \left( \psi i.mi.Hui.Mi\right) \tag{5}$$

where Mi is the mass of material i [kg]; Hui is the net heating value of material i [MJ/kg]; mi is the factor describing combustible properties of material i; Ψi is the factor assessing protected fire load of material i; and Af is the floor area of the fire compartment [m2 ].

HuiMi represents the total amount of energy that is contained in material i and released if combustion process is complete. Factor "m" is a non-dimensional factor between 0 and 1 representing combustion efficiency: m = 1 corresponds to complete combustion, and m = 0 if materials do not contribute to fire. The value of m = 0.8 is suggested for standard materials; the value of Hu = 17.5 MJ/kg is suggested for wood, resulting in 14 MJ/kg for (m.Hu).

Common building designs supposing the use of similar material quantities with the same heating capacity in installations can work with the statistical value of typical fire load density, as defined in EN 1991-1-2; if the designs are done in Slovakia, they follow Table A1 STN 730802. The value of accidental fire load stated in this standard is the weight of wood in kg calculated per unit of the floor area of fire compartment in m2 , whose heating capacity is the same as heating capacity of all combustible materials in this area. **Table 4** shows the data comparison.

The functional change of the original spaces changes the fire risk and number of persons. The change of building's fire height, e.g. by roof extension, changes the original building's fire height, fire protection requirements and evacuation plans. An increasing number of persons in the building change the requirements for the capacity and ventilation of emergency routes as well as the fire resistance of fire separation structures. Therefore, it is very important for the investment plan (as for space function and useful floor area extension) to be optimized in such a way that the original boundary conditions would not be changed fundamentally in terms of fire safety and would not require additional significant alternations to the building structures affecting their historic value.

The fire resistance requirements for building constructions specified in STN 73 0802 are directly dependent on calculated fire load, building's fire height and combustibility of constructions used in a building. It is optimal to prefer operations with a calculated fire load up to 50 kg/m<sup>2</sup> if the function of restored buildings containing mostly composite construction systems was changed. This value considers the operational fire load, surface finishes, effect of ventilation and fire-technical equipment. Classrooms, hotel rooms, coffee bars, offices or galleries are classified as spaces with medium fire load (medium fire development) (see **Table 5**).

Calculated fire load is determined by the relations:

$$\mathbf{p}\mathbf{v} = (\mathbf{p}\mathbf{n} + \mathbf{p}\mathbf{s}) . \mathbf{a}. \mathbf{b}. \mathbf{c} \left(\mathbf{k}\mathbf{g}/\mathbf{m}^2\right) \tag{6}$$

which depends on: pn—accidental fire load from furnishings given in Table A1 STN 730802 [19]; ps—stable fire load from windows, doors, floor and wall coverings given in Table A1 STN 730802; and a—coefficient of combustible materials (burning rate),

$$\mathbf{a} = \langle \mathbf{an}.\mathbf{pn} + \mathbf{a}.\mathbf{ps}\rangle / \mathbf{pn} + \mathbf{ps} \tag{7}$$

where an is given in Table A1 STN 730802, as is 0.9 and b is the coefficient of ventilation efficiency (ventilation rate),

$$\mathbf{b} = \mathbf{S}. \,\mathrm{k}/\mathbf{S} \mathbf{o}. \,\sqrt{\mathrm{ho}} \tag{8}$$

where S is the floor area of fire compartment; So is the total window area in fire compartment; ho is the average window height in fire compartment; k is the coefficient determined according to Section 4.5.4. STN 730802; and c is the factor of fire safety equipment efficiency,

$$\mathbf{c} = \mathbf{c1}.\mathbf{c2}.\mathbf{c3}.\mathbf{c4}\tag{9}$$

where c1 is the coefficient of fire detection (see **Table 2** STN 730802); c2 is the coefficient of fire brigade intervention (see **Tables 3** and **4** STN 730802); c3 is the coefficient of fixed fire extinguishing system (see **Table 5** STN 730802); and c4 is the coefficient of automatic fire sprinklers (see Table 6 STN 730802)

**Table 5** gives the calculated fire load of a typical fire compartment considering the most common use of space in historic buildings whose function was changed during their use. Model examples considered medium ventilation effect with the coefficient value b = 1. As the most historic buildings do not contain active fire safety equipment, all calculations considered the coefficient value c = 1. Subsequently, DFSB is determined depending on the calculated fire load value, combustibility of structures in the fire compartment and the building's fire height (see Table 8 STN 730802). DFSB expresses the summary of technical requirements for fire-separating structures; required minimum fire resistances of fire-separating structures are taken from Table 12 STN 730802.

If building conservation and finance costs are taken into account, it is not possible to carry out every functional change in listed buildings. The building can be classified as unsuitable if fire safety cannot be ensured with reasonable economic and operational costs. The new functional use must not reduce the existing fire safety. In general, listed buildings renovated by using only technical solutions cannot have any functional use. It is optimal for listed buildings to have as low fire risk as possible in terms of fire safety and subsequent fire safety measures [20].

#### **6. Evacuation**

People evacuated from a burning building are endangered by toxic gases released during combustion, flame, high temperature, smoke and lack of oxygen. The safe evacuation depends on the building's division into fire compartments using fire-separating structures. Their design is based on the assumption that fire will occur in a fire compartment so people present in other fire compartments will not be exposed to fire. The building's division into fire compartments is done in such a way that the life and health loss would be minimal or none. Fire-separating structures in fire compartments should prevent fire and its products from spreading. Separate fire compartments always form protected emergency routes.

**115**

routes.

*A Case Study on the Fire Safety in Historic Buildings in Slovakia*

Fire compartmentation in historic buildings is often limited due to the building conservation. This fact has a major impact on the safe evacuation. Open staircases, galleries and non-solid ceiling structures help fire spreading within such buildings. Thermal radiation, toxic gases and smoke are spread throughout the building. The fire intensity and time are increased by combustible materials in built-in ceilings, columns, staircases, wall facings and insulations of technical installations. This affects the safety and speed of people's movement within the affected fire compart-

Safety and fluency of evacuation in historic buildings with original layout and

• Open staircases—unprotected emergency routes with limited evacuation time

• Partially protected existing narrow spiral or ladder stairs limiting the speed of people's movement that can be used by a limited number of persons during

• Limited number of exits leading to an open area through locked doors without

• Missing other emergency routes—an absence of other staircases or alternative

• Insufficient capacity of escape lanes—inwards opening doors narrowing the

These circumstances cause the time for evacuation to be longer, people's safety to

The fire development and spreading is a function of time, that is time is crucial for evacuation of people or historic exhibits. Fluent evacuation is conditioned by the number and quality of emergency routes in terms of ventilation, slope, width and number of evacuated persons. Their ventilation and number depend on the building's fire height and the number of evacuated persons. There should be at least two emergency routes available for evacuation in every space; there is significantly better chance of people's survival in spaces directly affected by fire. Evacuated

• Missing exits from stairs leading to an open area outside the building

automatic opening during fire in single-story buildings

escape possibilities through windows, ladders, etc.

escape lane and slowing the people's movement speed

persons can use the emergency route that is less affected by fire.

requirement is ten times the air change per hour.

Staircases are used to evacuate people between floors in buildings. According to STN 730802 and the time required for safe evacuation, staircases can be divided into unprotected, partially protected and protected emergency

Unprotected routes are open staircases and those located within the fire compartment. Partially protected routes are staircases with fire-separating structures preventing the heat and smoke from spreading and those that are not adequately ventilated. Internally enclosed staircases without natural ventilation are the most common. Protected routes are staircases with fire-separating structures preventing the heat and smoke from spreading and natural or artificial ventilation. Routes of type A with natural or forced ventilation with a maximum evacuation time of 6 min are sufficient for historic buildings with the fire height up to 22.5 m. The ventilation

be lower and the risk for firefighting brigade to be higher.

*DOI: http://dx.doi.org/10.5772/intechopen.91241*

ment on unprotected emergency routes.

and no other evacuation staircase

functional use is often limited by:

evacuation

#### *A Case Study on the Fire Safety in Historic Buildings in Slovakia DOI: http://dx.doi.org/10.5772/intechopen.91241*

*Fire Safety and Management Awareness*

ventilation efficiency (ventilation rate),

safety equipment efficiency,

which depends on: pn—accidental fire load from furnishings given in Table A1 STN 730802 [19]; ps—stable fire load from windows, doors, floor and wall coverings given in Table A1 STN 730802; and a—coefficient of combustible materials (burning rate),

where an is given in Table A1 STN 730802, as is 0.9 and b is the coefficient of

where S is the floor area of fire compartment; So is the total window area in fire compartment; ho is the average window height in fire compartment; k is the coefficient determined according to Section 4.5.4. STN 730802; and c is the factor of fire

where c1 is the coefficient of fire detection (see **Table 2** STN 730802); c2 is the coefficient of fire brigade intervention (see **Tables 3** and **4** STN 730802); c3 is the coefficient of fixed fire extinguishing system (see **Table 5** STN 730802); and c4 is

**Table 5** gives the calculated fire load of a typical fire compartment considering the most common use of space in historic buildings whose function was changed during their use. Model examples considered medium ventilation effect with the coefficient value b = 1. As the most historic buildings do not contain active fire safety equipment, all calculations considered the coefficient value c = 1. Subsequently, DFSB is determined depending on the calculated fire load value, combustibility of structures in the fire compartment and the building's fire height (see Table 8 STN 730802). DFSB expresses the summary of technical requirements for fire-separating structures; required minimum fire resistances of fire-separating

If building conservation and finance costs are taken into account, it is not possible to carry out every functional change in listed buildings. The building can be classified as unsuitable if fire safety cannot be ensured with reasonable economic and operational costs. The new functional use must not reduce the existing fire safety. In general, listed buildings renovated by using only technical solutions cannot have any functional use. It is optimal for listed buildings to have as low fire risk

as possible in terms of fire safety and subsequent fire safety measures [20].

People evacuated from a burning building are endangered by toxic gases released during combustion, flame, high temperature, smoke and lack of oxygen. The safe evacuation depends on the building's division into fire compartments using fire-separating structures. Their design is based on the assumption that fire will occur in a fire compartment so people present in other fire compartments will not be exposed to fire. The building's division into fire compartments is done in such a way that the life and health loss would be minimal or none. Fire-separating structures in fire compartments should prevent fire and its products from spreading.

Separate fire compartments always form protected emergency routes.

the coefficient of automatic fire sprinklers (see Table 6 STN 730802)

structures are taken from Table 12 STN 730802.

b = S.k/So.

a = (an . pn + a . ps)/pn + ps (7)

√ho (8)

c = c1 . c2 . c3 . c4 (9)

**114**

**6. Evacuation**

Fire compartmentation in historic buildings is often limited due to the building conservation. This fact has a major impact on the safe evacuation. Open staircases, galleries and non-solid ceiling structures help fire spreading within such buildings. Thermal radiation, toxic gases and smoke are spread throughout the building. The fire intensity and time are increased by combustible materials in built-in ceilings, columns, staircases, wall facings and insulations of technical installations. This affects the safety and speed of people's movement within the affected fire compartment on unprotected emergency routes.

Safety and fluency of evacuation in historic buildings with original layout and functional use is often limited by:


These circumstances cause the time for evacuation to be longer, people's safety to be lower and the risk for firefighting brigade to be higher.

The fire development and spreading is a function of time, that is time is crucial for evacuation of people or historic exhibits. Fluent evacuation is conditioned by the number and quality of emergency routes in terms of ventilation, slope, width and number of evacuated persons. Their ventilation and number depend on the building's fire height and the number of evacuated persons. There should be at least two emergency routes available for evacuation in every space; there is significantly better chance of people's survival in spaces directly affected by fire. Evacuated persons can use the emergency route that is less affected by fire.

Staircases are used to evacuate people between floors in buildings. According to STN 730802 and the time required for safe evacuation, staircases can be divided into unprotected, partially protected and protected emergency routes.

Unprotected routes are open staircases and those located within the fire compartment. Partially protected routes are staircases with fire-separating structures preventing the heat and smoke from spreading and those that are not adequately ventilated. Internally enclosed staircases without natural ventilation are the most common. Protected routes are staircases with fire-separating structures preventing the heat and smoke from spreading and natural or artificial ventilation. Routes of type A with natural or forced ventilation with a maximum evacuation time of 6 min are sufficient for historic buildings with the fire height up to 22.5 m. The ventilation requirement is ten times the air change per hour.

#### **6.1 Solution example of a model building's restoration in terms of evacuation**

The change of building's functional use and fire load usually results in an increasing number of persons in building compared to the original solution. The evacuation conditions are also changed if the building's fire height is changed, e.g. due to the addition of one or two floors into the attic. Since both cases fundamentally affect the evacuation conditions, it is necessary to check the original emergency routes and modify so that they would be suitable for the new number of evacuated persons or longer emergency route.

Here is the solution example of a model building. The new owner of a manor house changed the building's functional use and fire height by adding a floor into the unused attic space. The manor house is a typical baroque building with a U-shaped ground plan. The manor house had originally three above-ground floors with a mansard roof. The building once served as a residence of a noble family. After restoration, it will serve as a hotel. There are social spaces containing inner halls, smaller salons, restaurants, kitchen and sanitary operational background on the ground floor and first floor. Hotel rooms with technical and operational facilities are located on the upper floors (see **Figure 5**).

Each side wing contains one double-wing staircase that was originally open and classified as unprotected at the time of evacuation. Designed building's alternation by hotel rooms built in the attic changed building's fire height and extended staircases beyond the allowable dimensional limits defined in Table 16 STN 730802. It was necessary to alter existing staircases in the side wings. The staircases on each floor were fire-separated from the other fire-loaded spaces and ventilated through existing windows facing the inner courtyard (see **Figure 5**).

**Figure 5.** *Emergency routes on the first floor leading to an open area in a model solution of the restored manor house.*

**117**

**Thanks**

*A Case Study on the Fire Safety in Historic Buildings in Slovakia*

To achieve higher fire safety in historic buildings whose functional use was changed, it is recommended to optimize the fire risk considering combustibility of building structures and building's fire height. Authors J. Li, H. Li, B. Zhou and X. Wang in their work "Investigation and Statistical Analysis of Fire Load of 83 Historic Buildings in Beijing" analyzed the fire load in timber historic buildings where the primary requirement of the restoration was the optimization of acciden-

The building should be divided into fire compartments if it is acceptable in terms of the building conservation. If it is possible, another emergency route with direct ventilation should be created. This route would also serve for firefighting intervention. The large roof spaces should be divided into smaller units using fireseparating walls overlapping the roof by at least 300 mm. An accidental fire loads should be excluded from the attic space. All attic entrances should be provided with self-closing fire doors. Interventions into the original floors should be reduced. Hidden cavities in the floors should be analyzed in the project documentation due to the load-bearing capacity during the fire intervention as well as in terms of the occurrence of hidden fire caused by short circuits in electrical installations. All cable entries, pipes and anchoring of heavy chandeliers through ceilings should be carefully fire-sealed. The copper roofing on wooden decking or wooden shingles should be replaced with non-combustible roofing made of burnt tiles or slate—see an example of the castle of Krásna Hôrka. The baroque buildings on the Svatá Hora near the town of Příbram in the Czech Republic underwent a similar restoration after a large fire in 1798. The fire affected buildings' wooden roofs as in Krásna Hôrka. The original wooden shingles were replaced by ceramic tiles after fire. The roof spaces in buildings of significant historic importance should be equipped with an automatic fire alarm system, ideally supplemented with an automatic fire extinguishing system. An example of such solution is the protection of the supporting truss members in St. Vitus Cathedral in Prague, Czech Republic. There is an electrical fire alarm and automatic sprinkler fire extinguishing system installed in

The spaces containing visible combustible load-bearing and fire-separating structures should be equipped with an automatic fire alarm system. Water sources that can be used for fire extinguishing should be sufficient and located near the building. Accessibility of water sources is often complicated in historic buildings.

Access roads should be verified and optimized within natural possibilities. It is important for the building's operation and its fire safety to have functional firefighting equipment and fire-trained staff so that the risks associated with building's

The work is published with the financial support of the project VEGA 1/0248/19.

The current fire documentation should be elaborated and updated so as to provide sufficient information on the evacuation plans for persons and exhibits, building's structural design, firefighting water sources and technical condition of

capacity equipped with

One of the possibilities is the use of water tanks with 10 m3

restoration and maintenance can be minimized [22–24].

The work presents knowledge from the author's design practice.

*DOI: http://dx.doi.org/10.5772/intechopen.91241*

**7. Conclusions**

tal fire load [20].

its roof space.

a 50-m-long fire hose [21].

access and emergency roads.

#### **7. Conclusions**

*Fire Safety and Management Awareness*

evacuated persons or longer emergency route.

ties are located on the upper floors (see **Figure 5**).

existing windows facing the inner courtyard (see **Figure 5**).

**6.1 Solution example of a model building's restoration in terms of evacuation**

The change of building's functional use and fire load usually results in an increasing number of persons in building compared to the original solution. The evacuation conditions are also changed if the building's fire height is changed, e.g. due to the addition of one or two floors into the attic. Since both cases fundamentally affect the evacuation conditions, it is necessary to check the original emergency routes and modify so that they would be suitable for the new number of

Here is the solution example of a model building. The new owner of a manor house changed the building's functional use and fire height by adding a floor into the unused attic space. The manor house is a typical baroque building with a U-shaped ground plan. The manor house had originally three above-ground floors with a mansard roof. The building once served as a residence of a noble family. After restoration, it will serve as a hotel. There are social spaces containing inner halls, smaller salons, restaurants, kitchen and sanitary operational background on the ground floor and first floor. Hotel rooms with technical and operational facili-

Each side wing contains one double-wing staircase that was originally open and classified as unprotected at the time of evacuation. Designed building's alternation by hotel rooms built in the attic changed building's fire height and extended staircases beyond the allowable dimensional limits defined in Table 16 STN 730802. It was necessary to alter existing staircases in the side wings. The staircases on each floor were fire-separated from the other fire-loaded spaces and ventilated through

*Emergency routes on the first floor leading to an open area in a model solution of the restored manor house.*

**116**

**Figure 5.**

To achieve higher fire safety in historic buildings whose functional use was changed, it is recommended to optimize the fire risk considering combustibility of building structures and building's fire height. Authors J. Li, H. Li, B. Zhou and X. Wang in their work "Investigation and Statistical Analysis of Fire Load of 83 Historic Buildings in Beijing" analyzed the fire load in timber historic buildings where the primary requirement of the restoration was the optimization of accidental fire load [20].

The building should be divided into fire compartments if it is acceptable in terms of the building conservation. If it is possible, another emergency route with direct ventilation should be created. This route would also serve for firefighting intervention. The large roof spaces should be divided into smaller units using fireseparating walls overlapping the roof by at least 300 mm. An accidental fire loads should be excluded from the attic space. All attic entrances should be provided with self-closing fire doors. Interventions into the original floors should be reduced.

Hidden cavities in the floors should be analyzed in the project documentation due to the load-bearing capacity during the fire intervention as well as in terms of the occurrence of hidden fire caused by short circuits in electrical installations. All cable entries, pipes and anchoring of heavy chandeliers through ceilings should be carefully fire-sealed. The copper roofing on wooden decking or wooden shingles should be replaced with non-combustible roofing made of burnt tiles or slate—see an example of the castle of Krásna Hôrka. The baroque buildings on the Svatá Hora near the town of Příbram in the Czech Republic underwent a similar restoration after a large fire in 1798. The fire affected buildings' wooden roofs as in Krásna Hôrka. The original wooden shingles were replaced by ceramic tiles after fire. The roof spaces in buildings of significant historic importance should be equipped with an automatic fire alarm system, ideally supplemented with an automatic fire extinguishing system. An example of such solution is the protection of the supporting truss members in St. Vitus Cathedral in Prague, Czech Republic. There is an electrical fire alarm and automatic sprinkler fire extinguishing system installed in its roof space.

The spaces containing visible combustible load-bearing and fire-separating structures should be equipped with an automatic fire alarm system. Water sources that can be used for fire extinguishing should be sufficient and located near the building. Accessibility of water sources is often complicated in historic buildings. One of the possibilities is the use of water tanks with 10 m3 capacity equipped with a 50-m-long fire hose [21].

Access roads should be verified and optimized within natural possibilities. It is important for the building's operation and its fire safety to have functional firefighting equipment and fire-trained staff so that the risks associated with building's restoration and maintenance can be minimized [22–24].

The current fire documentation should be elaborated and updated so as to provide sufficient information on the evacuation plans for persons and exhibits, building's structural design, firefighting water sources and technical condition of access and emergency roads.

#### **Thanks**

The work is published with the financial support of the project VEGA 1/0248/19. The work presents knowledge from the author's design practice.

*Fire Safety and Management Awareness*

### **Author details**

Agnes Iringová Faculty of Civil Engineering, University of Žilina, Žilina, Slovakia

\*Address all correspondence to: agnes.iringova@fstav.uniza.sk

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**119**

*A Case Study on the Fire Safety in Historic Buildings in Slovakia*

Praha: ČVUT Publishing House; 2005.

[11] Iringova A, Idunk R. Assessment and usability of historic trusses in terms of fire protection—A case study. International Wood Products Journal.

[12] STN 730821. Fire protection of buildings. In: Fire Resistance of Engineering Structures. Praha:

[13] STN EN 1995-1-1 + A1. Eurocode 5. Design of Wooden Structures—Part 1-1. Generally—General Rules and Rules for Buildings. Bratislava: SUTN; 2008

[14] STN EN 1995-1-2. Eurocode 5. In: Design of Wooden Structures—Part 1-2. General Rules—Design of Structures for Fire Effect. Bratislava: SUTN; 2008

[15] Vassart O, Zhao B, Cajot LG,

[16] Gašpercová S, Makovická L, Kostelanský T. Assessment of fire protection in the castle of Trenčín. Available from: https://stavba.tzb-info.

[17] STN EN 338. Constructional wood. In: Strength Classes. Bratislava: SUTN;

[18] Emery S. Emergency Plans for Heritage Buildings and Collections. London: English Heritage; 2011

[19] STN 73 0802. Structural fire protection. In: Common Regulations.

[20] Li J, Li H, Zhou B, Wang X. Investigation and statistical analysis

Bratislava: SUTN; 2010

cz/historicke-stavby/17908

Robert F, Meyer U, Frangi A. Eurocodes: Background applications structural fire design. In: Report EUR26698 EN. European Union; 2014. ISSN

336 p. ISBN 80-0103157-8

2017;**8**(2):80-87

UNMZ; 1973

1831-9424

2010

*DOI: http://dx.doi.org/10.5772/intechopen.91241*

[1] Stewart K, Haire S. Fire Safety Management in Traditional Buildings:

[2] Egri J. Fire in the castle of Krásna Hôrka. In: PYROMEETING—Fire Protection of Historical Monuments.

[3] Firenet: History of Fire Safety (online). 2009. Available from: http:// www.fire.org.uk/history-of-fire-safety.

[4] STN 73 0834. Fire safety of buildings. In: Changes in Buildings. Bratislava:

[5] Svoboda P, Polatova E. Methodology

for fire protection of accessible monuments. In: Proceedings of the Bridges to Fire Protection of Cultural Monuments, Prague. 2015. pp. 32-37

[6] Caston P. Historic roof trusses between 1500 and 1700 in

German speaking Central Europe: Documentation, analysis, and

development. In: Second International Congress on Construction History, Queens' College, Cambridge

University, March 29 to April 04. 2006.

[7] STN EN 1991-1-1. Eurocode 1. In: Load of Structures—Part 1-1. Bratislava:

[8] STN EN 1991-1-3. Eurocode 1. In: Load of Structures—Part 1-3. Bratislava:

[9] STN EN 1991-1-4. Eurocode 1: Load of Structures—Part 1-4. Bratislava:

[10] Wald F et al. Calculation of Fire Resistance of Building Structures.

Part 1. Principles and Practise. Edinburgh: Historic Scotland; 2010.

ISBN 978-1-84917-035-2

Brno. 2013

**References**

SUTN; 2010

pp. 579-597

SUTN; 2007

SUTN; 2007

SUTN; 2007

html

*A Case Study on the Fire Safety in Historic Buildings in Slovakia DOI: http://dx.doi.org/10.5772/intechopen.91241*

#### **References**

*Fire Safety and Management Awareness*

**118**

**Author details**

Agnes Iringová

Faculty of Civil Engineering, University of Žilina, Žilina, Slovakia

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

\*Address all correspondence to: agnes.iringova@fstav.uniza.sk

provided the original work is properly cited.

[1] Stewart K, Haire S. Fire Safety Management in Traditional Buildings: Part 1. Principles and Practise. Edinburgh: Historic Scotland; 2010. ISBN 978-1-84917-035-2

[2] Egri J. Fire in the castle of Krásna Hôrka. In: PYROMEETING—Fire Protection of Historical Monuments. Brno. 2013

[3] Firenet: History of Fire Safety (online). 2009. Available from: http:// www.fire.org.uk/history-of-fire-safety. html

[4] STN 73 0834. Fire safety of buildings. In: Changes in Buildings. Bratislava: SUTN; 2010

[5] Svoboda P, Polatova E. Methodology for fire protection of accessible monuments. In: Proceedings of the Bridges to Fire Protection of Cultural Monuments, Prague. 2015. pp. 32-37

[6] Caston P. Historic roof trusses between 1500 and 1700 in German speaking Central Europe: Documentation, analysis, and development. In: Second International Congress on Construction History, Queens' College, Cambridge University, March 29 to April 04. 2006. pp. 579-597

[7] STN EN 1991-1-1. Eurocode 1. In: Load of Structures—Part 1-1. Bratislava: SUTN; 2007

[8] STN EN 1991-1-3. Eurocode 1. In: Load of Structures—Part 1-3. Bratislava: SUTN; 2007

[9] STN EN 1991-1-4. Eurocode 1: Load of Structures—Part 1-4. Bratislava: SUTN; 2007

[10] Wald F et al. Calculation of Fire Resistance of Building Structures.

Praha: ČVUT Publishing House; 2005. 336 p. ISBN 80-0103157-8

[11] Iringova A, Idunk R. Assessment and usability of historic trusses in terms of fire protection—A case study. International Wood Products Journal. 2017;**8**(2):80-87

[12] STN 730821. Fire protection of buildings. In: Fire Resistance of Engineering Structures. Praha: UNMZ; 1973

[13] STN EN 1995-1-1 + A1. Eurocode 5. Design of Wooden Structures—Part 1-1. Generally—General Rules and Rules for Buildings. Bratislava: SUTN; 2008

[14] STN EN 1995-1-2. Eurocode 5. In: Design of Wooden Structures—Part 1-2. General Rules—Design of Structures for Fire Effect. Bratislava: SUTN; 2008

[15] Vassart O, Zhao B, Cajot LG, Robert F, Meyer U, Frangi A. Eurocodes: Background applications structural fire design. In: Report EUR26698 EN. European Union; 2014. ISSN 1831-9424

[16] Gašpercová S, Makovická L, Kostelanský T. Assessment of fire protection in the castle of Trenčín. Available from: https://stavba.tzb-info. cz/historicke-stavby/17908

[17] STN EN 338. Constructional wood. In: Strength Classes. Bratislava: SUTN; 2010

[18] Emery S. Emergency Plans for Heritage Buildings and Collections. London: English Heritage; 2011

[19] STN 73 0802. Structural fire protection. In: Common Regulations. Bratislava: SUTN; 2010

[20] Li J, Li H, Zhou B, Wang X. Investigation and statistical analysis of fire load of 83 historic buildings in Beijing. International Journal of Architectural Heritage. 2018

[21] Karlsen E. Fire Protection of Norwegian Cultural Heritage. Norway: Directorate for Cultural Heritage (Riksantikvaren). Available from: http:// www.arcchip.cz/w04/w04\_karlsen.pdf

[22] Ditlev J, Orrainen M. Managing fire safety in historical buildings. In: CFPA-E Guideline No. 30: 2013. F Copenhagen: CFPA Europe; 2013

[23] German Insurance Association. Brandschutz in historischen Gebäuden. Empfehlungen zur Schadenverhütung (VdS 2171). 2008-2012

[24] Jensen G, Cowi AS. Manual Fire Extinguishing Equipment for Protection of Heritage. Norway: Riksantikvaren the Norwegian Directorate for Cultural Heritage Historic Scotland: Technical Conservation, Research and Edication Group; 2006. ISBN: 82-7574-039-8

**121**

**Chapter 7**

**Abstract**

carried out.

**1. Introduction**

Gas Industry

*Rachid Nait-Said and Fatiha Zidani*

**Keywords:** BLEVE effects, CFD, FDS, fireball, LES, QRA

BLEVE Fireball Effects in a Gas

Industry: A Numerical Modeling

Applied to the Case of an Algeria

This chapter presents the numerical modeling of the BLEVE (Boiling Liquid Expanding Vapor Explosion) thermal effects. The goal is to highlight the possibility to use numerical data in order to estimate the potential damage that would be caused by the BLEVE, based on quantitative risk analysis (QRA). The numerical modeling is carried out using the computational fluid dynamics (CFD) code Fire Dynamics Simulator (FDS) version 6. The BLEVE is defined as a fireball, and in this work, its source is modeled as a vertical release of hot fuel in a short time. Moreover, the fireball dynamics is based on a single-step combustion using an eddy dissipation concept (EDC) model coupled with the default large eddy simulation (LES) turbulence model. Fireball characteristics (diameter, height, heat flux and lifetime) issued from a large-scale experiment are used to demonstrate the ability of FDS to simulate the various steps of the BLEVE phenomenon from ignition up to total burnout. A comparison between BAM (Bundesanstalt für Materialforschung und –prüfung, Allemagne) experiment data and predictions highlights the ability of FDS to model BLEVE effects. From this, a numerical study of the thermal effects of BLEVE in the largest gas field in Algeria was

After the industrial revolution of the nineteenth century, the world has experienced significant growth in new technologies embedded in the process industry such as gas processing, manufacture of transportation means, etc. In these installations, several fuel elements are present and require special attention in order to avoid accidents whose consequences have severe impacts on people, equipment, and environment. The most common accidents encountered in the chemical and petrochemical process industry are fires, explosions, and toxic releases. Considering the number of existing and future installations, the consequences of

*Brady Manescau, Khaled Chetehouna, Ilyas Sellami,* 

#### **Chapter 7**

*Fire Safety and Management Awareness*

of fire load of 83 historic buildings in Beijing. International Journal of Architectural Heritage. 2018

[21] Karlsen E. Fire Protection of Norwegian Cultural Heritage. Norway: Directorate for Cultural Heritage

CFPA Europe; 2013

(VdS 2171). 2008-2012

82-7574-039-8

(Riksantikvaren). Available from: http:// www.arcchip.cz/w04/w04\_karlsen.pdf

[22] Ditlev J, Orrainen M. Managing fire safety in historical buildings. In: CFPA-E Guideline No. 30: 2013. F Copenhagen:

[23] German Insurance Association. Brandschutz in historischen Gebäuden. Empfehlungen zur Schadenverhütung

[24] Jensen G, Cowi AS. Manual Fire Extinguishing Equipment for Protection of Heritage. Norway: Riksantikvaren the Norwegian Directorate for Cultural Heritage Historic Scotland: Technical Conservation, Research and Edication Group; 2006. ISBN:

**120**

## BLEVE Fireball Effects in a Gas Industry: A Numerical Modeling Applied to the Case of an Algeria Gas Industry

*Brady Manescau, Khaled Chetehouna, Ilyas Sellami, Rachid Nait-Said and Fatiha Zidani*

## **Abstract**

This chapter presents the numerical modeling of the BLEVE (Boiling Liquid Expanding Vapor Explosion) thermal effects. The goal is to highlight the possibility to use numerical data in order to estimate the potential damage that would be caused by the BLEVE, based on quantitative risk analysis (QRA). The numerical modeling is carried out using the computational fluid dynamics (CFD) code Fire Dynamics Simulator (FDS) version 6. The BLEVE is defined as a fireball, and in this work, its source is modeled as a vertical release of hot fuel in a short time. Moreover, the fireball dynamics is based on a single-step combustion using an eddy dissipation concept (EDC) model coupled with the default large eddy simulation (LES) turbulence model. Fireball characteristics (diameter, height, heat flux and lifetime) issued from a large-scale experiment are used to demonstrate the ability of FDS to simulate the various steps of the BLEVE phenomenon from ignition up to total burnout. A comparison between BAM (Bundesanstalt für Materialforschung und –prüfung, Allemagne) experiment data and predictions highlights the ability of FDS to model BLEVE effects. From this, a numerical study of the thermal effects of BLEVE in the largest gas field in Algeria was carried out.

**Keywords:** BLEVE effects, CFD, FDS, fireball, LES, QRA

#### **1. Introduction**

After the industrial revolution of the nineteenth century, the world has experienced significant growth in new technologies embedded in the process industry such as gas processing, manufacture of transportation means, etc. In these installations, several fuel elements are present and require special attention in order to avoid accidents whose consequences have severe impacts on people, equipment, and environment. The most common accidents encountered in the chemical and petrochemical process industry are fires, explosions, and toxic releases. Considering the number of existing and future installations, the consequences of these types of accidents remain a major concern for decision-makers, industrial experts, and fire safety analysts.

In the context of defining an accurate assessment of the safety of industrial facilities, risk analysts often use quantitative risk analysis (QRA) [1]. It is an analysis method that makes it possible to understand and quantify the consequences of accidental phenomena (thermal radiation, overpressure, toxicity dose).

Among the accidental phenomena most observed in the process industry is the boiling liquid expanding vapor explosion (BLEVE). It corresponds to a violent vaporization of explosive nature following the rupture (loss of confinement) of a tank containing a liquid at a temperature significantly higher than its normal boiling point at atmospheric pressure [2]. Between 1940 and 2005, the different BLEVEs listed have cost more than 1000 lives and have injured more than 10,000 people in addition to harming property worth billions of dollars [3]. In addition to human lives and material goods, BLEVE has hazardous effects on the environment; it can release dangerous substances likely to attack the environment. Considering this, it is important to estimate the potential damage that would be caused by such an explosion. In this context, several studies have been conducted to analyze the BLEVE mechanisms. Thermal radiation hazards associated with liquefied petroleum gas (LPG) releases from pressurized storage were studied by Roberts [4]. He established correlations allowing to obtain the fireball characteristic parameters from the fuel mass (diameter, lifetime, and heat flux). From these mathematical laws, Crocker and Napier [5] evaluated fire and explosion hazards of LPG. They showed that these models overestimate the risks associated with jet fires, fireballs, and BLEVE blast effects. Prugh [6], in his part, studied the effects of fuel type and fuel quantity on fireball diameter, duration, and energy and the relationships between fireball energy, distance from the fireball, and consequences of personnel and property exposure.

Roberts et al. [7] presented results from a series of experimental tests performed by the Health and Safety Laboratory in the context of JIVE project (hazards consequences of jet fire interaction with vessels containing pressurized liquids). During these tests, several propane tanks were exposed to fires. They allowed to identify the conditions of temperature and rupture pressure, failure mode, as well as the fireball characteristics. In a study conducted by Abbasi et al. [3], the mechanism, the causes, the consequences, the hand calculation methods, and the preventive strategies associated with BLEVEs were presented in an excellent review. Based on medium-scale experimental tests, Birk et al. [8] concluded that the liquid part does not contribute to the generation of shock waves. They proposed a model based on the TNO model that uses the vapor part to calculate the expansion energy. Other works like Bubbico and Marchini [9] and Chen et al. [10] give information on the fact that BLEVE evolution process is characterized by two-phase flow with an overpressure effect.

In works cited above, there are empirical and semiempirical approaches which provide data highlighting the characteristics of BLEVE. However, these approaches are not very satisfactory because they usually include an experimentally adjusted reduction factor and mostly overestimate the BLEVE effects [11–13]. Furthermore, they do not consider the effect of buildings, obstructions, and topography for specific facilities. In addition, the data provided by these approaches may not ensure enough repertory for conducting an in-depth QRA.

In order to overcome the empirical approach limitations, it is necessary to use the computational fluid dynamics (CFD) modeling which appears as a powerful complementary tool for experimental and theoretical studies. Considering the complexity of the BLEVE phenomenon process, current published CFD simulation studies [14–19] focus only on certain BLEVE aspects, such as fireball formation,

**123**

*BLEVE Fireball Effects in a Gas Industry: A Numerical Modeling Applied to the Case…*

ing turbulence, combustion process, heat transfer, and geometry.

without considering vessel disintegration. Indeed, with a sufficiently fine numerical resolution, it is possible to carry out simulations of explosion phenomena consider-

Among the numerical studies on the BLEVE, Yakush and Makhviladze [14] compared the fireball lifetime predictions from two turbulence models (based on RANS and LES approach) and the fireball lifetime obtained by the experimental correlation of Roper et al. [15]. The simulations were performed by the CFD code FDS from NIST version 4. They showed that the simulation using LES model better predicts fireball dynamics than the simulation using RANS model. Other simulations were made using the CFD code FDS [16–18]. The FDS validation was carried out using the experimental data such as the BAM BLEVE experiment [19]. They evaluated the code capabilities to simulate the fireball characteristics (diameter, lifetime, flame dynamics, and structure). In addition to FDS, other CFD codes are used to simulate fireball characteristics such as OpenFOAM, Ansys CFX, etc. Indeed, Mishra et al. [20] performed a CFD investigation on a peroxy-fuel BLEVE using the CFD commercial code Ansys CFX, and Shelke et al. [21] used the OpenFOAM CFD code. They highlighted the abilities of these CFD codes to predict the reactive flows present in a fireball

In this chapter, in addition to evaluating the capability of the CFD code FDS to predict the BLEVE characteristics, an evaluation of the BLEVE thermal effects on a real gas processing plant is presented. The evaluation of the CFD code is made using data obtained from empirical correlations and large-scale experimental data issued from the literature. The calculations are carried out using the FDS code

In this context, an overview of the BLEVE phenomenon is presented in the second part of the chapter. In the third part, the capability of FDS to predict BLEVE characteristics is presented in comparison with experimental data. In the fourth part, the BLEVE thermal effects on a real case study are illustrated to finish with

BLEVE is described as a violent explosive vaporization resulting from the rupture of a tank containing a liquid at a temperature significantly above its boiling

BLEVE can occur with any liquid, flammable or not, when heated and pressurized into a closed container. Two types of BLEVE can be distinguished, cold BLEVE and hot BLEVE, depending on the temperature at which the rupture of the

In this illustration, the hot BLEVE with a flammable liquid is studied. The BLEVE explosion of hydrocarbon fuels (e.g., LPG, LNG, etc.) is characterized by the formation of fireball and the release of intense thermal radiation in a

In the focus to characterize the BLEVE phenomenon with enough accuracy, it is important to define an experimental setup with a fine and controlled

*DOI: http://dx.doi.org/10.5772/intechopen.92990*

conclusions and perspectives in the last part.

**2.2 Description of the different BLEVE tests**

**2. BLEVE presentation**

point at atmospheric pressure.

**2.1 BLEVE definition**

enclosure occurs.

short time.

such as BLEVE.

version 6.

#### *BLEVE Fireball Effects in a Gas Industry: A Numerical Modeling Applied to the Case… DOI: http://dx.doi.org/10.5772/intechopen.92990*

without considering vessel disintegration. Indeed, with a sufficiently fine numerical resolution, it is possible to carry out simulations of explosion phenomena considering turbulence, combustion process, heat transfer, and geometry.

Among the numerical studies on the BLEVE, Yakush and Makhviladze [14] compared the fireball lifetime predictions from two turbulence models (based on RANS and LES approach) and the fireball lifetime obtained by the experimental correlation of Roper et al. [15]. The simulations were performed by the CFD code FDS from NIST version 4. They showed that the simulation using LES model better predicts fireball dynamics than the simulation using RANS model. Other simulations were made using the CFD code FDS [16–18]. The FDS validation was carried out using the experimental data such as the BAM BLEVE experiment [19]. They evaluated the code capabilities to simulate the fireball characteristics (diameter, lifetime, flame dynamics, and structure). In addition to FDS, other CFD codes are used to simulate fireball characteristics such as OpenFOAM, Ansys CFX, etc. Indeed, Mishra et al. [20] performed a CFD investigation on a peroxy-fuel BLEVE using the CFD commercial code Ansys CFX, and Shelke et al. [21] used the OpenFOAM CFD code. They highlighted the abilities of these CFD codes to predict the reactive flows present in a fireball such as BLEVE.

In this chapter, in addition to evaluating the capability of the CFD code FDS to predict the BLEVE characteristics, an evaluation of the BLEVE thermal effects on a real gas processing plant is presented. The evaluation of the CFD code is made using data obtained from empirical correlations and large-scale experimental data issued from the literature. The calculations are carried out using the FDS code version 6.

In this context, an overview of the BLEVE phenomenon is presented in the second part of the chapter. In the third part, the capability of FDS to predict BLEVE characteristics is presented in comparison with experimental data. In the fourth part, the BLEVE thermal effects on a real case study are illustrated to finish with conclusions and perspectives in the last part.

#### **2. BLEVE presentation**

#### **2.1 BLEVE definition**

*Fire Safety and Management Awareness*

experts, and fire safety analysts.

these types of accidents remain a major concern for decision-makers, industrial

In the context of defining an accurate assessment of the safety of industrial facilities, risk analysts often use quantitative risk analysis (QRA) [1]. It is an analysis method that makes it possible to understand and quantify the consequences of accidental phenomena (thermal radiation, overpressure, toxicity dose).

Among the accidental phenomena most observed in the process industry is the boiling liquid expanding vapor explosion (BLEVE). It corresponds to a violent vaporization of explosive nature following the rupture (loss of confinement) of a tank containing a liquid at a temperature significantly higher than its normal boiling point at atmospheric pressure [2]. Between 1940 and 2005, the different BLEVEs listed have cost more than 1000 lives and have injured more than 10,000 people in addition to harming property worth billions of dollars [3]. In addition to human lives and material goods, BLEVE has hazardous effects on the environment; it can release dangerous substances likely to attack the environment. Considering this, it is important to estimate the potential damage that would be caused by such an explosion. In this context, several studies have been conducted to analyze the BLEVE mechanisms. Thermal radiation hazards associated with liquefied petroleum gas (LPG) releases from pressurized storage were studied by Roberts [4]. He established correlations allowing to obtain the fireball characteristic parameters from the fuel mass (diameter, lifetime, and heat flux). From these mathematical laws, Crocker and Napier [5] evaluated fire and explosion hazards of LPG. They showed that these models overestimate the risks associated with jet fires, fireballs, and BLEVE blast effects. Prugh [6], in his part, studied the effects of fuel type and fuel quantity on fireball diameter, duration, and energy and the relationships between fireball energy, distance from

the fireball, and consequences of personnel and property exposure.

enough repertory for conducting an in-depth QRA.

Roberts et al. [7] presented results from a series of experimental tests performed by the Health and Safety Laboratory in the context of JIVE project (hazards consequences of jet fire interaction with vessels containing pressurized liquids). During these tests, several propane tanks were exposed to fires. They allowed to identify the conditions of temperature and rupture pressure, failure mode, as well as the fireball characteristics. In a study conducted by Abbasi et al. [3], the mechanism, the causes, the consequences, the hand calculation methods, and the preventive strategies associated with BLEVEs were presented in an excellent review. Based on medium-scale experimental tests, Birk et al. [8] concluded that the liquid part does not contribute to the generation of shock waves. They proposed a model based on the TNO model that uses the vapor part to calculate the expansion energy. Other works like Bubbico and Marchini [9] and Chen et al. [10] give information on the fact that BLEVE evolution process is characterized by two-phase flow with an

In works cited above, there are empirical and semiempirical approaches which provide data highlighting the characteristics of BLEVE. However, these approaches are not very satisfactory because they usually include an experimentally adjusted reduction factor and mostly overestimate the BLEVE effects [11–13]. Furthermore, they do not consider the effect of buildings, obstructions, and topography for specific facilities. In addition, the data provided by these approaches may not ensure

In order to overcome the empirical approach limitations, it is necessary to use the computational fluid dynamics (CFD) modeling which appears as a powerful complementary tool for experimental and theoretical studies. Considering the complexity of the BLEVE phenomenon process, current published CFD simulation studies [14–19] focus only on certain BLEVE aspects, such as fireball formation,

**122**

overpressure effect.

BLEVE is described as a violent explosive vaporization resulting from the rupture of a tank containing a liquid at a temperature significantly above its boiling point at atmospheric pressure.

BLEVE can occur with any liquid, flammable or not, when heated and pressurized into a closed container. Two types of BLEVE can be distinguished, cold BLEVE and hot BLEVE, depending on the temperature at which the rupture of the enclosure occurs.

In this illustration, the hot BLEVE with a flammable liquid is studied. The BLEVE explosion of hydrocarbon fuels (e.g., LPG, LNG, etc.) is characterized by the formation of fireball and the release of intense thermal radiation in a short time.

#### **2.2 Description of the different BLEVE tests**

In the focus to characterize the BLEVE phenomenon with enough accuracy, it is important to define an experimental setup with a fine and controlled instrumentation. However, the current measurement instruments do not allow the proper acquisition of results during a BLEVE test due to its magnitude. In addition, the high cost of this type of test and considering respect for the environment, there are few experimental tests that deal with this kind of phenomenon. In the literature [19, 22], there are large-scale experiment tests: the BAM test (Bundesanstalt für Materialforschung und –prüfung, Allemagne), the British Gas experiments, and the JIVE tests (hazards consequences of jet fire interaction with vessels containing pressurized liquids, 1994/1995).

In this chapter, only the BAM experiment is used to evaluate the capability of FDS to predict BLEVE characteristics.

By doing a little reminder on the BLEVE phenomenon, in 1998, the BAM conducted a BLEVE test with a road tank of 45 m3 of capacity, containing 5 tons of commercial propane (fill liquid level 22%) [19, 22]. The wagon was exposed to a fuel pool fire. In this test, an instrumentation has been performed to obtain physical quantities such as heat flux, temperature, and pressure.

In the goal to make a comparison between empirical law and numerical modeling, the next sections will present the equations used for the empirical laws and the different models proposed to simulate the reactive flows inducted by the fireball.

#### **2.3 BLEVE modeling using empirical laws**

In order to predict the fireball effects, different authors proposed correlations to predict fireball diameter and lifetime based on fuel quantity [4, 23–30]. These correlations are given in the following equations:

$$D\_{\rm FB} = \mathfrak{a}\_1 \mathbf{M}^{b1} \tag{1}$$

$$\mathbf{t}\_{FB} = \mathfrak{a}\_2 \mathbf{M}^{b\_2} \tag{2}$$

where *DFB* is the fireball diameter, *M* is the fuel mass, *tFB* is the fireball lifetime, and *a*1, *b*1, *a*2, and *b*2 are empirical constants.

With the difficulty to choose good coefficients which give better correlation for the fireball characterization, a comparative analysis made by Satyanarayana et al. [31] to define the best correlations which describe the fireball diameter and lifetime is given as follows:

$$D\_{FB} = \mathsf{G.14} \, M^{0.325} \tag{3}$$

$$t\_{FB} = \mathbf{0}.41M^{0.340} \tag{4}$$

Equations (3) and (4) are used in this study in order to compare with the experiment data and CFD predictions.

To estimate the incident radiation received by a target at a given distance, the solid-flame model may be used [23, 27]:

$$
\dot{q}\_r^n = E\_p \cdot F\_v \cdot \pi\_{atm} \tag{5}
$$

**125**

section.

written as [32]:

where *D*<sup>∗</sup>

the specific heat.

δ*x*

computational cost [18, 39].

mends a *D*<sup>∗</sup> \_

*BLEVE Fireball Effects in a Gas Industry: A Numerical Modeling Applied to the Case…*

computing capability using message-passing interface (MPI) [26, 33].

The numerical modelings were performed using the CFD code FDS 6.5.3 [32]. This one solves the Navier–Stokes equations based on an explicit finite difference scheme. Moreover, it models the thermally driven flow with an emphasis on smoke and heat transport. It is a LES model using a uniform mesh and has parallel

The modeling of the fire is based on a reaction rate considered as infinitely fast, and the combustion is modeled using the EDC of Magnussen and Hjertager [34–36]. The turbulent combustion processes are based on the governing equations for the mass fraction of the chemical species, such as *Cx Hy*, *O*2, *CO*2, *H*2*O*, and *N*<sup>2</sup>

> *y* \_ 2

*H*2*O* + 3.76(*x* +

*y* \_ 4

) *N*<sup>2</sup> (6)

, is

) (7)

is the heat release rate, and *cp* is

)(*O*<sup>2</sup> + 3.76 *N*2) → *xCO*<sup>2</sup> +

Considering the complexity of the BLEVE phenomenon, only the fireball is modeled in this work. Indeed, as the published CFD studies say, the container disintegration is complicated to model and is not considered. For that, the present

The fuel used is propane. Its heat of combustion is set to 46,334 kJ/kg. The ejection surface was calculated using the approach of Makhviladze et al. [38]. The fuel releases as a hot gas with a temperature equal to 700°C. The ignition of the mixture air/fuel is ensured by an autoignition. The extinction model and turbulence model

The numerical simulations are carried out in a rectangular 3D domain with dimensions of 200 m × 200 m × 300 m assimilated to an open ambient environment. These dimensions are obtained from the max-diameter and the max-height of the fireball calculated using the empirical correlations presented in the second

In the mesh resolution, it is necessary to determine the fire characteristic diameter according to its heat release rate (HRR). This diameter, denoted *D*<sup>∗</sup>

= ( *Q*̇ \_

 ρ∞ *c*∞ *T*∞ √

From obtaining the characteristic diameter, the optimal mesh size of the domain

ratio between 4 and 16 to produce accurate results at a moderate

Based on several experiences, the US Nuclear Regulatory Commission recom-

In order to model a fireball using FDS, it is important to define the good mesh size. For that, a comparison between experiment data and numerical data using

\_ *g*

, where δ*x* is the nominal mesh size.

*D*∗

δ*x*

is the characteristic fire diameter, *Q*̇

*DOI: http://dx.doi.org/10.5772/intechopen.92990*

**3. Numerical modeling of BLEVE**

**3.1 Fire source modeling**

*Cx Hy* + (*x* +

**3.2 Mesh sensitivity analysis**

is given by the dimensionless ratio *D*<sup>∗</sup> \_

through a single step as follows [37]:

*y* \_ 4

used in simulations are the default code models.

study is based on the BLEVE modeling by fuel release.

where *q*̇ *<sup>r</sup>* ″ is the radiation received by target,*Ep* is the surface emissive power, *Fv* is the view factor, and τ*atm* is the atmospheric attenuation factor (transmissivity).

*BLEVE Fireball Effects in a Gas Industry: A Numerical Modeling Applied to the Case… DOI: http://dx.doi.org/10.5772/intechopen.92990*

#### **3. Numerical modeling of BLEVE**

The numerical modelings were performed using the CFD code FDS 6.5.3 [32]. This one solves the Navier–Stokes equations based on an explicit finite difference scheme. Moreover, it models the thermally driven flow with an emphasis on smoke and heat transport. It is a LES model using a uniform mesh and has parallel computing capability using message-passing interface (MPI) [26, 33].

#### **3.1 Fire source modeling**

*Fire Safety and Management Awareness*

pressurized liquids, 1994/1995).

fireball.

is given as follows:

ment data and CFD predictions.

solid-flame model may be used [23, 27]:

FDS to predict BLEVE characteristics.

**2.3 BLEVE modeling using empirical laws**

correlations are given in the following equations:

and *a*1, *b*1, *a*2, and *b*2 are empirical constants.

quantities such as heat flux, temperature, and pressure.

instrumentation. However, the current measurement instruments do not allow the proper acquisition of results during a BLEVE test due to its magnitude. In addition, the high cost of this type of test and considering respect for the environment, there are few experimental tests that deal with this kind of phenomenon. In the literature [19, 22], there are large-scale experiment tests: the BAM test (Bundesanstalt für Materialforschung und –prüfung, Allemagne), the British Gas experiments, and the JIVE tests (hazards consequences of jet fire interaction with vessels containing

In this chapter, only the BAM experiment is used to evaluate the capability of

By doing a little reminder on the BLEVE phenomenon, in 1998, the BAM conducted a BLEVE test with a road tank of 45 m3 of capacity, containing 5 tons of commercial propane (fill liquid level 22%) [19, 22]. The wagon was exposed to a fuel pool fire. In this test, an instrumentation has been performed to obtain physical

In the goal to make a comparison between empirical law and numerical modeling, the next sections will present the equations used for the empirical laws and the different models proposed to simulate the reactive flows inducted by the

In order to predict the fireball effects, different authors proposed correlations to predict fireball diameter and lifetime based on fuel quantity [4, 23–30]. These

where *DFB* is the fireball diameter, *M* is the fuel mass, *tFB* is the fireball lifetime,

With the difficulty to choose good coefficients which give better correlation for the fireball characterization, a comparative analysis made by Satyanarayana et al. [31] to define the best correlations which describe the fireball diameter and lifetime

Equations (3) and (4) are used in this study in order to compare with the experi-

″ is the radiation received by target,*Ep* is the surface emissive power, *Fv* is

To estimate the incident radiation received by a target at a given distance, the

the view factor, and τ*atm* is the atmospheric attenuation factor (transmissivity).

*q*̇ *r n*

*DFB* = *a*1 *M<sup>b</sup>*<sup>1</sup> (1)

*tFB* = *a*2 *M<sup>b</sup>*<sup>2</sup> (2)

*DFB* = 6.14 *M*0.325 (3)

*tFB* = 0.41 *M*0.340 (4)

= *Ep* ⋅ *Fv* ⋅ τ*atm* (5)

**124**

where *q*̇ *r*

The modeling of the fire is based on a reaction rate considered as infinitely fast, and the combustion is modeled using the EDC of Magnussen and Hjertager [34–36]. The turbulent combustion processes are based on the governing equations for the mass fraction of the chemical species, such as *Cx Hy*, *O*2, *CO*2, *H*2*O*, and *N*<sup>2</sup> through a single step as follows [37]:

$$\rm C\_xH\_y + \left(x + \frac{y}{4}\right)\left(O\_2 + 3.76N\_2\right) \rightarrow xCO\_2 + \frac{y}{2}H\_2O + 3.76\left(x + \frac{y}{4}\right)N\_2 \tag{6}$$

Considering the complexity of the BLEVE phenomenon, only the fireball is modeled in this work. Indeed, as the published CFD studies say, the container disintegration is complicated to model and is not considered. For that, the present study is based on the BLEVE modeling by fuel release.

The fuel used is propane. Its heat of combustion is set to 46,334 kJ/kg. The ejection surface was calculated using the approach of Makhviladze et al. [38]. The fuel releases as a hot gas with a temperature equal to 700°C. The ignition of the mixture air/fuel is ensured by an autoignition. The extinction model and turbulence model used in simulations are the default code models.

The numerical simulations are carried out in a rectangular 3D domain with dimensions of 200 m × 200 m × 300 m assimilated to an open ambient environment. These dimensions are obtained from the max-diameter and the max-height of the fireball calculated using the empirical correlations presented in the second section.

#### **3.2 Mesh sensitivity analysis**

In the mesh resolution, it is necessary to determine the fire characteristic diameter according to its heat release rate (HRR). This diameter, denoted *D*<sup>∗</sup> , is written as [32]: = ( *Q*̇ \_

$$D^\* = \left(\frac{\dot{Q}}{\rho\_{\text{ov}} c\_{\text{ov}} T\_{\text{ov}} \sqrt{\xi}}\right) \tag{7}$$

where *D*<sup>∗</sup> is the characteristic fire diameter, *Q*̇ is the heat release rate, and *cp* is the specific heat.

From obtaining the characteristic diameter, the optimal mesh size of the domain is given by the dimensionless ratio *D*<sup>∗</sup> \_ δ*x* , where δ*x* is the nominal mesh size.

Based on several experiences, the US Nuclear Regulatory Commission recommends a *D*<sup>∗</sup> \_ δ*x* ratio between 4 and 16 to produce accurate results at a moderate computational cost [18, 39].

In order to model a fireball using FDS, it is important to define the good mesh size. For that, a comparison between experiment data and numerical data using

four mesh sizes is made in **Figure 1(a)** and **(b)**. The different mesh sizes are obtained from the US Nuclear Regulatory Commission recommendation. The numerical simulations are carried out in a rectangular 3D domain with dimensions of 200 m × 200 m × 300 m as mentioned previously.

The comparisons between the experiment and the predictions for the four different meshes are made based on the evolution of the heat flux and the fireball height (cf. **Figure 1**). The heat flux was measured at 30 m over the ground from the projected center of the fireball on the ground under the fireball, and the height was obtained from the fireball center to the ground level. These figures show that the numerical results obtained from the mesh sizes of 0.5 m and 1 m converge with the experimental results, while the results from the mesh sizes of 2 m and 4 m diverge. Moreover, the mesh size of 0.5 m offers more precision than the results obtained with a mesh size of 1 m as shown by the root-mean-square Error (cf. **Table 1**).

From **Figure 1(a)** and **(b)**, the numerical simulation with a mesh size of 0.5 m is more precise but requires a calculation time 50 times greater than the calculation carried out with a mesh size of 1 m (cf. **Table 1**). Thus, by wanting to conciliate precision and optimal calculation time, the mesh size of 1 m will be used for the rest of numerical simulations. This mesh size allows solving the Navier–Stokes equations with a good accuracy. Indeed, with the mesh size of 1 m, the different numerical models such as the turbulence model based on the Deardorff model, the combustion model based on the EDC definition, and the extinction model based on the critical temperature flame are very well calculated for giving a very nice modeling of the fireball. Moreover, taking into account the mesh size

**Figure 1.** *Mesh resolution on (a) the height of fireball center and (b) the heat flux at 30 m on ground level.*


**127**

**Figure 2.**

*and (d) 6 s.*

*BLEVE Fireball Effects in a Gas Industry: A Numerical Modeling Applied to the Case…*

*Simulation of the fireball temperature field with mesh size 1 m in the cross-section at (a) 2 s, (b) 3 s, (c) 4 s,* 

*DOI: http://dx.doi.org/10.5772/intechopen.92990*

#### **Table 1.**

*Results of mesh sensitivity analysis.*

*BLEVE Fireball Effects in a Gas Industry: A Numerical Modeling Applied to the Case… DOI: http://dx.doi.org/10.5772/intechopen.92990*

**Figure 2.** *Simulation of the fireball temperature field with mesh size 1 m in the cross-section at (a) 2 s, (b) 3 s, (c) 4 s, and (d) 6 s.*

*Fire Safety and Management Awareness*

Error (cf. **Table 1**).

of 200 m × 200 m × 300 m as mentioned previously.

four mesh sizes is made in **Figure 1(a)** and **(b)**. The different mesh sizes are obtained from the US Nuclear Regulatory Commission recommendation. The numerical simulations are carried out in a rectangular 3D domain with dimensions

The comparisons between the experiment and the predictions for the four different meshes are made based on the evolution of the heat flux and the fireball height (cf. **Figure 1**). The heat flux was measured at 30 m over the ground from the projected center of the fireball on the ground under the fireball, and the height was obtained from the fireball center to the ground level. These figures show that the numerical results obtained from the mesh sizes of 0.5 m and 1 m converge with the experimental results, while the results from the mesh sizes of 2 m and 4 m diverge. Moreover, the mesh size of 0.5 m offers more precision than the results obtained with a mesh size of 1 m as shown by the root-mean-square

From **Figure 1(a)** and **(b)**, the numerical simulation with a mesh size of 0.5 m is more precise but requires a calculation time 50 times greater than the calculation carried out with a mesh size of 1 m (cf. **Table 1**). Thus, by wanting to conciliate precision and optimal calculation time, the mesh size of 1 m will be used for the rest of numerical simulations. This mesh size allows solving the Navier–Stokes equations with a good accuracy. Indeed, with the mesh size of 1 m, the different numerical models such as the turbulence model based on the Deardorff model, the combustion model based on the EDC definition, and the extinction model based on the critical temperature flame are very well calculated for giving a very nice modeling of the fireball. Moreover, taking into account the mesh size

**Numerical grid Number of cells Root-mean-square error CPU time (min)**

Mesh size 4 m 187,500 60.22 34.09 2 Mesh size 2 m 1,500,000 59.01 21.56 14 Mesh size 1 m 12,000,000 9.74 16.24 161 Mesh size 0.5 m 96,000,000 5.86 13.23 8000

*Mesh resolution on (a) the height of fireball center and (b) the heat flux at 30 m on ground level.*

**Height (m) Heat flux (kW/m2**

**)**

**126**

**Table 1.**

**Figure 1.**

*Results of mesh sensitivity analysis.*


**Table 2.**

*Comparison between numerical data and BAM test.*

of 2 and 4 m, there is an important divergency on the solving of the previous numerical models.

Working with the mesh size of 1 m, **Figure 2(a)–(d)** shows the evolution and the development of the fireball structure at different times (2, 3, 4, and 6 s) after the fuel release to the atmosphere. From these pictures, the evolutions of the temperature field obtained from the numerical modeling highlight the same observations made by Hurley et al. [40]. It is observed that the diameter of the flame increases the height and the time, and Hurley et al. have observed that the diameter of the fireball reaches its maximum at about 6 s with a value of 100 m as diameter. And, by making a comparison with the numerical data, this one agrees with experimental results.

Moreover, considering that the flame temperature of a hydrocarbon fire can approach about 1300°C, it is shown in **Figure 2(a)–(d)** that the predicted field temperature represents the diameter of the fireball during its evolution. In this context, the reactive flows modeled using this mesh resolution come close themselves to the flame dynamics of BLEVE phenomenon.

In conclusion, FDS can predict BLEVE characteristics after a good definition of the mesh size and the fuel release rate. For another case of validation, **Table 2** illustrates the comparison between numerical data and BAM test. In this one, it is observed that the predictions of the parameters such as max-diameter, lifetime, and max-height of the fireball agree with experiment with a better precision than empirical estimates.

#### **4. BLEVE thermal effects: case study for a Hassi R'Mel gas processing plant**

From the previous analyses, it has been shown that FDS code is able to simulate the evolution and development of a fireball in comparison with experimental test, considering that it is possible to predict the evolution and thermal effects of a BLEVE in a real installation. In addition, from the numerical results obtained in the previous section, it is necessary to use a nice mesh size in order to make an accurate modeling of a fireball under FDS and a good knowledge of the mass and the release rate of the fuel. Moreover, the definition of a calculation domain that considers the recirculation and the reactive flows during the fireball expansion is very important to justify a good numerical calculation. So, respecting the previous numerical recommendations, it is possible to simulate thermal effects of BLEVE in a real installation such as in Hassi R'Mel Gas Processing Plant.

#### **4.1 Description of the gas processing plant and the ignition source**

The gas processing plant studied in this work is defined as the Module Processing Plant 3 (MPP3) of SONATRACH Company at Hassi R'Mel gas field

**129**

**Table 3.**

**Figure 3.**

*Numerical MPP3-plant.*

Volume (m3

Propane density (kg/m3

*Technical characteristics of the accumulator D108.*

*BLEVE Fireball Effects in a Gas Industry: A Numerical Modeling Applied to the Case…*

(located about 550 km south of Algiers). This MPP3-plant consists of three identical gas processing trains that mainly produce natural gas (with a produc-

the configuration of the MPP3-plant. The origin of the explosion is taken at the level of a pressurized propane accumulator D108 located in the MPP3-plant as

The choice of the accumulator D108 is based on the opinions of the risk analysts who consider it as one of the most critical systems in the MPP3-plant, which can generate catastrophic BLEVE accidents [41]. **Table 3** summarizes the technical

The numerical modeling of the MPP3-plant described above is carried out in an open calculation domain of 300 m × 300 m × 360 m. The dimensions of this domain are chosen based on the fireball diameter and height calculated using empirical correlations. The calculations are carried out under atmospheric conditions with a relative humidity of 40% and an ambient temperature of 20°C. The plant configuration is modeled as solid obstructions considering the real equipment dimensions

The calculations were performed with a time step of 0.01 s and took 2729 minutes with a mesh size of 1 m (i.e., 32,400,000 meshes) using 90 CPUs. The simulation is performed using the default numerical models. The ejection surface was calculated using the approach of Makhviladze et al. [38] as mentioned in Section 3. The origin of the explosion is taken at the level of the D108 as mentioned previously. Using the

**Characteristics Values** Operating temperature (°C) 40 Operating pressure (bar) 14.5

) 50

) 483.6

/day), LPG, and condensate. **Figure 3** illustrates

*DOI: http://dx.doi.org/10.5772/intechopen.92990*

characteristics of the D108 vessel used in our calculation.

tion capacity of 60 million m3

shown in **Figure 3**.

**4.2 Boundary conditions**

of the three MPP3-plant trains.

*BLEVE Fireball Effects in a Gas Industry: A Numerical Modeling Applied to the Case… DOI: http://dx.doi.org/10.5772/intechopen.92990*

(located about 550 km south of Algiers). This MPP3-plant consists of three identical gas processing trains that mainly produce natural gas (with a production capacity of 60 million m3 /day), LPG, and condensate. **Figure 3** illustrates the configuration of the MPP3-plant. The origin of the explosion is taken at the level of a pressurized propane accumulator D108 located in the MPP3-plant as shown in **Figure 3**.

The choice of the accumulator D108 is based on the opinions of the risk analysts who consider it as one of the most critical systems in the MPP3-plant, which can generate catastrophic BLEVE accidents [41]. **Table 3** summarizes the technical characteristics of the D108 vessel used in our calculation.

#### **4.2 Boundary conditions**

*Fire Safety and Management Awareness*

*Comparison between numerical data and BAM test.*

numerical models.

**Fireball Characteristics**

**Table 2.**

with experimental results.

empirical estimates.

**processing plant**

flame dynamics of BLEVE phenomenon.

of 2 and 4 m, there is an important divergency on the solving of the previous

**Experiment Empirical Present** 

Max-diameter (m) 100 98 101 1.41 0.71 Duration (s) 7.2 7.4 7.8 0.14 0.42 Max-height (m) 100 74 99 18.38 0.71

**data**

**RMSE (Empirical)**

**RMSE (Present data)**

Working with the mesh size of 1 m, **Figure 2(a)–(d)** shows the evolution and the development of the fireball structure at different times (2, 3, 4, and 6 s) after the fuel release to the atmosphere. From these pictures, the evolutions of the temperature field obtained from the numerical modeling highlight the same observations made by Hurley et al. [40]. It is observed that the diameter of the flame increases the height and the time, and Hurley et al. have observed that the diameter of the fireball reaches its maximum at about 6 s with a value of 100 m as diameter. And, by making a comparison with the numerical data, this one agrees

Moreover, considering that the flame temperature of a hydrocarbon fire can approach about 1300°C, it is shown in **Figure 2(a)–(d)** that the predicted field temperature represents the diameter of the fireball during its evolution. In this context, the reactive flows modeled using this mesh resolution come close themselves to the

In conclusion, FDS can predict BLEVE characteristics after a good definition of the mesh size and the fuel release rate. For another case of validation, **Table 2** illustrates the comparison between numerical data and BAM test. In this one, it is observed that the predictions of the parameters such as max-diameter, lifetime, and max-height of the fireball agree with experiment with a better precision than

From the previous analyses, it has been shown that FDS code is able to simulate

the evolution and development of a fireball in comparison with experimental test, considering that it is possible to predict the evolution and thermal effects of a BLEVE in a real installation. In addition, from the numerical results obtained in the previous section, it is necessary to use a nice mesh size in order to make an accurate modeling of a fireball under FDS and a good knowledge of the mass and the release rate of the fuel. Moreover, the definition of a calculation domain that considers the recirculation and the reactive flows during the fireball expansion is very important to justify a good numerical calculation. So, respecting the previous numerical recommendations, it is possible to simulate thermal effects of BLEVE in

**4. BLEVE thermal effects: case study for a Hassi R'Mel gas** 

a real installation such as in Hassi R'Mel Gas Processing Plant.

**4.1 Description of the gas processing plant and the ignition source**

The gas processing plant studied in this work is defined as the Module Processing Plant 3 (MPP3) of SONATRACH Company at Hassi R'Mel gas field

**128**

The numerical modeling of the MPP3-plant described above is carried out in an open calculation domain of 300 m × 300 m × 360 m. The dimensions of this domain are chosen based on the fireball diameter and height calculated using empirical correlations. The calculations are carried out under atmospheric conditions with a relative humidity of 40% and an ambient temperature of 20°C. The plant configuration is modeled as solid obstructions considering the real equipment dimensions of the three MPP3-plant trains.

The calculations were performed with a time step of 0.01 s and took 2729 minutes with a mesh size of 1 m (i.e., 32,400,000 meshes) using 90 CPUs. The simulation is performed using the default numerical models. The ejection surface was calculated using the approach of Makhviladze et al. [38] as mentioned in Section 3. The origin of the explosion is taken at the level of the D108 as mentioned previously. Using the

**Figure 3.** *Numerical MPP3-plant.*


#### **Table 3.**

*Technical characteristics of the accumulator D108.*

same modeling approach presented in Section 3, the BLEVE is modeled through the ejection of 24,180 kg of hot propane with a velocity of 100 m/s.

#### **5. Results and discussions**

In the previous section, it is shown that the comparison of the predicted fireball diameter and lifetime with the empirical values is similar to the experimental data. However, the predicted height is better than the empirical value in comparison with experiment data.

Considering the real installation, there are no experimental data and so no possibility to compare with empirical values and numerical data. In these conditions, the comparison is made only between the numerical and empirical data based on the evaluation of BLEVE characteristics. Moreover, considering the observations made in the previous section, the results issued from the BLEVE simulation in the MPP3-plant show similar observations. Indeed, in **Table 4**, the predicted fireball diameter and lifetime are like the empirical values, but the empirical height is underestimated by comparing to the predicted value.

Taking into account the comparisons obtained previously, it is possible to say that the evolution and the development of the fireball predicted by FDS in the MPP3-plant would be representative of reality. **Figure 4** shows the simulation of the fireball at two different times in the studied plant. With this simulation, it is possible to follow the evolution of different physical parameters in a spatiotemporal manner such as heat flux, heat release rate, species concentrations, flame temperature, etc. In this paper, only the prediction of heat flux is studied.

**Figure 5** presents the comparison between the prediction and the empirical approach based on the evolution of heat flux over time at 50 and 70 m at ground level. It is found that the prediction provides a temporal evolution of the heat flux representative of the reality in comparison with the empirical one which gives a constant value. Indeed, during the first moments, a maximum peak of the heat flux is observed. This maximum value represents the heat flux emitted by the fireball when the latter is near to the ground. With the fireball elevation in height, the heat flux received at ground level decreases. This is represented by the evolution of the heat flux predicted by FDS code. From these comparisons, it is justified that the data provided by the numerical simulation give a more realistic support during a QRA.

Indeed, as indicated in introduction, risk analysis requires knowledge of representative input data of the phenomenon to be studied. Thus, depending on the data, a risk analysis can be well estimated, underestimated, and overestimated. As a result, it is preferable to use the data obtained from numerical simulation in comparison with the data obtained from empirical laws.


**131**

**Figure 4.**

**Figure 5.**

*ground level.*

*Fireball simulation at (a) 2 s and (b) 8 s.*

height less than 70 m.

also a tool that can be used in a QRA.

*BLEVE Fireball Effects in a Gas Industry: A Numerical Modeling Applied to the Case…*

In addition to the evolutions of the heat flux presented in **Figure 5**, the same observation is found in **Figure 6(a)** and **(b)**. These figures show the heat flux distribution at 1 s and 4 s in order to better observe the heat flux field over the entire MPP3-plant. With this illustration, it is shown that it is necessary to present the results during the first few seconds. Indeed, considering the heat flux distribution throughout the plant, it is observed during the first instants that the heat flux intensity is important at the explosion source and decreases in the remote zones. In **Figure 6**, it is observed that the heat flux intensity decreases at the explosion

*Comparison between empirical and thermal flux prediction at the distance of (a) 50 m and (b) 75 m on the* 

origin and increases in the remote zones with the fireball evolution in terms of diameter and height. This observation is like the reality and is true only for a fireball

In conclusion, the BLEVE thermal effects in Hassi R'Mel Gas Processing Plant are well predicted by FDS. In addition, the predictions of FDS give information which allows a better understanding on BLEVE phenomenon. It can be considered

*DOI: http://dx.doi.org/10.5772/intechopen.92990*

**Table 4.**

*Comparison between numerical and empirical data for MPP3-plant.*

*BLEVE Fireball Effects in a Gas Industry: A Numerical Modeling Applied to the Case… DOI: http://dx.doi.org/10.5772/intechopen.92990*

**Figure 4.** *Fireball simulation at (a) 2 s and (b) 8 s.*

**Figure 5.**

*Fire Safety and Management Awareness*

**5. Results and discussions**

experiment data.

studied.

ing a QRA.

same modeling approach presented in Section 3, the BLEVE is modeled through the

In the previous section, it is shown that the comparison of the predicted fireball diameter and lifetime with the empirical values is similar to the experimental data. However, the predicted height is better than the empirical value in comparison with

Considering the real installation, there are no experimental data and so no possibility to compare with empirical values and numerical data. In these conditions, the comparison is made only between the numerical and empirical data based on the evaluation of BLEVE characteristics. Moreover, considering the observations made in the previous section, the results issued from the BLEVE simulation in the MPP3-plant show similar observations. Indeed, in **Table 4**, the predicted fireball diameter and lifetime are like the empirical values, but the empirical height is

Taking into account the comparisons obtained previously, it is possible to say that the evolution and the development of the fireball predicted by FDS in the MPP3-plant would be representative of reality. **Figure 4** shows the simulation of the fireball at two different times in the studied plant. With this simulation, it is possible to follow the evolution of different physical parameters in a spatiotemporal manner such as heat flux, heat release rate, species concentrations, flame temperature, etc. In this paper, only the prediction of heat flux is

**Figure 5** presents the comparison between the prediction and the empirical approach based on the evolution of heat flux over time at 50 and 70 m at ground level. It is found that the prediction provides a temporal evolution of the heat flux representative of the reality in comparison with the empirical one which gives a constant value. Indeed, during the first moments, a maximum peak of the heat flux is observed. This maximum value represents the heat flux emitted by the fireball when the latter is near to the ground. With the fireball elevation in height, the heat flux received at ground level decreases. This is represented by the evolution of the heat flux predicted by FDS code. From these comparisons, it is justified that the data provided by the numerical simulation give a more realistic support dur-

Indeed, as indicated in introduction, risk analysis requires knowledge of representative input data of the phenomenon to be studied. Thus, depending on the data, a risk analysis can be well estimated, underestimated, and overestimated. As a result, it is preferable to use the data obtained from numerical simulation in com-

**Fireball characteristics Empirical Present data** Max-diameter (m) 163 174 Duration (s) 12.7 14 Max-height (m) 122 160

ejection of 24,180 kg of hot propane with a velocity of 100 m/s.

underestimated by comparing to the predicted value.

parison with the data obtained from empirical laws.

*Comparison between numerical and empirical data for MPP3-plant.*

**130**

**Table 4.**

*Comparison between empirical and thermal flux prediction at the distance of (a) 50 m and (b) 75 m on the ground level.*

In addition to the evolutions of the heat flux presented in **Figure 5**, the same observation is found in **Figure 6(a)** and **(b)**. These figures show the heat flux distribution at 1 s and 4 s in order to better observe the heat flux field over the entire MPP3-plant. With this illustration, it is shown that it is necessary to present the results during the first few seconds. Indeed, considering the heat flux distribution throughout the plant, it is observed during the first instants that the heat flux intensity is important at the explosion source and decreases in the remote zones.

In **Figure 6**, it is observed that the heat flux intensity decreases at the explosion origin and increases in the remote zones with the fireball evolution in terms of diameter and height. This observation is like the reality and is true only for a fireball height less than 70 m.

In conclusion, the BLEVE thermal effects in Hassi R'Mel Gas Processing Plant are well predicted by FDS. In addition, the predictions of FDS give information which allows a better understanding on BLEVE phenomenon. It can be considered also a tool that can be used in a QRA.

**Figure 6.** *Thermal radiation contour plot in the x-y plane at (a) 1 s and (b) 4 s.*

## **6. Conclusion**

In this chapter, a CFD evaluation of the thermal effects of the BLEVE phenomenon in a real installation is presented. This evaluation firstly required the code validation to correctly simulate the BLEVE characteristics in comparison with the data that come from literature experimental test. Numerical calculations were performed using the CFD FDS code version 6.5.3 with the default numerical models. The results show a good agreement between the predictions and the experiments, justifying a nice capability to FDS to simulate the fireball dynamics with a good accuracy.

After highlighting that FDS can predict the spatiotemporal evolution of a fireball in comparison with an experimental test, a simulation of the BLEVE is performed in a real installation. This involves studying the fireball thermal effects resulting from the explosion of a pressurized propane tank in an Algerian gas treatment unit. The results obtained showed great relevance of carrying out this type of study in

**133**

**Author details**

Brady Manescau1

Fatiha Zidani<sup>2</sup>

\*, Khaled Chetehouna1

2 – Mostefa Ben Boulaïd, Fesdis, Batna, Algeria

provided the original work is properly cited.

Kasdi Merbah University – Ouargla, Ouargla, Algeria

\*Address all correspondence to: brady.manescau@insa-cvl.fr

1 INSA Centre Val de Loire, Univ. Orléans, PRISME, Bourges, France

2 LRPI Laboratory, Institute of Health and Industrial Safety, University of Batna

3 DIRE Laboratory, Department of Applied Engineering, Institute of Technology,

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

, Ilyas Sellami1,2,3, Rachid Nait-Said3

and

*BLEVE Fireball Effects in a Gas Industry: A Numerical Modeling Applied to the Case…*

this type of installation. From the numerical data, it is shown that the heat flux reaches a maximum value during the first moments at ground level and decreases with the elevation of the fireball. In addition, comparisons between prediction and empirical models, based on heat flux evolution, show that prediction is representative of reality compared to empirical models. Thus, for a risk analysis in this type of

Moreover, the current results can be considered as a first step to make a modeling of the BLEVE phenomenon, and in order to improve the global description of this phenomenon, it will be necessary to consider, in a next work, the container

*DOI: http://dx.doi.org/10.5772/intechopen.92990*

installation, it is preferable to use the numerical approach.

disintegration in order to model the complete BLEVE process.

#### *BLEVE Fireball Effects in a Gas Industry: A Numerical Modeling Applied to the Case… DOI: http://dx.doi.org/10.5772/intechopen.92990*

this type of installation. From the numerical data, it is shown that the heat flux reaches a maximum value during the first moments at ground level and decreases with the elevation of the fireball. In addition, comparisons between prediction and empirical models, based on heat flux evolution, show that prediction is representative of reality compared to empirical models. Thus, for a risk analysis in this type of installation, it is preferable to use the numerical approach.

Moreover, the current results can be considered as a first step to make a modeling of the BLEVE phenomenon, and in order to improve the global description of this phenomenon, it will be necessary to consider, in a next work, the container disintegration in order to model the complete BLEVE process.

## **Author details**

*Fire Safety and Management Awareness*

**132**

**6. Conclusion**

**Figure 6.**

In this chapter, a CFD evaluation of the thermal effects of the BLEVE phenomenon in a real installation is presented. This evaluation firstly required the code validation to correctly simulate the BLEVE characteristics in comparison with the data that come from literature experimental test. Numerical calculations were performed using the CFD FDS code version 6.5.3 with the default numerical models. The results show a good agreement between the predictions and the experiments, justifying a nice capability to FDS to simulate the fireball dynamics with a good accuracy.

*Thermal radiation contour plot in the x-y plane at (a) 1 s and (b) 4 s.*

After highlighting that FDS can predict the spatiotemporal evolution of a fireball in comparison with an experimental test, a simulation of the BLEVE is performed in a real installation. This involves studying the fireball thermal effects resulting from the explosion of a pressurized propane tank in an Algerian gas treatment unit. The results obtained showed great relevance of carrying out this type of study in

Brady Manescau1 \*, Khaled Chetehouna1 , Ilyas Sellami1,2,3, Rachid Nait-Said3 and Fatiha Zidani<sup>2</sup>

1 INSA Centre Val de Loire, Univ. Orléans, PRISME, Bourges, France

2 LRPI Laboratory, Institute of Health and Industrial Safety, University of Batna 2 – Mostefa Ben Boulaïd, Fesdis, Batna, Algeria

3 DIRE Laboratory, Department of Applied Engineering, Institute of Technology, Kasdi Merbah University – Ouargla, Ouargla, Algeria

\*Address all correspondence to: brady.manescau@insa-cvl.fr

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Buchlin JM, Rambaud P.

2014;**33**(3):274-284

2015;**95**:159-171

[13] Van Den Berg AC, Van Der Voort MM, Weerheijm J,

BLEVE overpressure: Multiscale comparison of blast wave

modeling. Process Safety Progress.

[12] Laboureur D et al. A closer look at BLEVE overpressure. Process Safety and Environment Protection. May

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[14] Yakush SE, Makhviladze GM. Large Eddy simulation of hydrocarbon fireballs Institute for Problems in mechanics. In: Proceedings of the European Combustion Meeting. 2005

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*Fire Safety and Management Awareness*

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## *Edited by Fahmina Zafar and Anujit Ghosal*

To ensure a healthy lifestyle, fire safety and protocols are essential. The population boom, economic crunches, and excessive exploitation of nature have enhanced the possibilities of destruction due to an event of a fire. Computational simulations enacting case studies and incorporation of fire safety protocols in daily routines can help in avoiding such mishaps.

Published in London, UK © 2020 IntechOpen © stockphoto / iStock

Fire Safety and Management Awareness

Fire Safety

and Management Awareness

*Edited by Fahmina Zafar and Anujit Ghosal*