**3. Results**

The error changes (G) in the operation of the water meter for status Q2=0 were tested for two cases: without UFR and with UFR in operation at water meter no. 3.

**Figure 4.** Error changes (G) in the operation of water meter no. 3 during time in the function of Q3 flow without UFR in operation (circles) and with the UFR in operation (crosses).

With the criterion described by equation (2), steady state flow stabilisation time, tst was de‐ fined:

Water volume flown through the water meter was defined by:

ume in the vessel, the water flow rate Q was calculated.

measuring at water meter propeller in stillstand [12].

) and 0.1 kg (for Qn).

cases: without UFR and with UFR in operation at water meter no. 3.

Qmin), 0.01 kg (for Qt

138 Water Supply System Analysis - Selected Topics

**3. Results**


in operation (circles) and with the UFR in operation (crosses).

**G (%)**

**•** the difference in reading on the water meter prior and after measuring, and

**•** measuring water quantity in the vessel (of 15 to 200 litres in volume) and water density. By measuring time (with stop-watch) between two readings, through the defined water vol‐

During accuracy measurements, water meter readings were as follows: 2.5 centilitres, 1 deci‐ litre and 1 litre. Measurement accuracy of water quantity in the vessel was 0.005 kg (for

Error changes in the operation of the water meter described by equation (1), were tested by applying two method by stopping the water meter: according to the valid Protocol of the Republic of Serbia, the status on the water meter and the scale was read prior and after

The error changes (G) in the operation of the water meter for status Q2=0 were tested for two

0 15 30 45 60 75 90 105 120 135 150 165 180 195 210 225 240 255 270 285 300 315 330 345 360 375

Q3=1,3 l/h Q3=1,3 l/h Q3=3,0 l/h Q3=2,8 l/h Q3=5,2 l/h Q3=5,0 l/h Q3=7,1 l/h Q3=6,7 l/h Q3=12,7 l/h Q3=12,4 l/h Q3=19,6 l/h Q3=18,7 l/h Q3=25,5-25,6 l/h Q3=24,4-24,6 l/h

**t (min)**

**Figure 4.** Error changes (G) in the operation of water meter no. 3 during time in the function of Q3 flow without UFR

**Figure 5.** Stabilisation time of water flow in the installation tst in the function of flow Q3.


**Table 2.** Stabilisation time of water flow in the installation tst in the function of flow Q3.


UFR (right) in operation.

balancing decrease.

99.5-28.93=70.57%.

flow rates Q2=0.03-0.0385 m3

**G (%)**

0 100 200 300 400 500 600 700 800 900 1000 1100 1200

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Q3=1,1-1,3 l/h Q3=1,1-1,2 l/h UFR Q3=2,8-3,0 l/h Q3=2,8-2,9 l/h UFR Q3=4,7-5,1 l/h Q3=4,6-5,1 l/h UFR Q3=6,1-6,3 l/h Q3=6,1 l/h UFR Q3=11,2-12,3 l/h Q3=11,1-12,0 l/h UFR Q3=19,7-21,0 l/h Q3=19,2-20,6 l/h UFR Q3=23,6-25,4 l/h Q3=23,0-24,6 l/h UFR Q3=5,1-5,3 l/h Q3=4,9-5,3 l/h UFR

**Q2 (l/h)**

**Figure 7.** Error (Gb) in water balancing on the rig in the function of flow rates Q2 and Q3, without UFR (left) and with

The highest balancing error values for the tested statuses are +0.9 and -16.6%. By increasing flow rate Q2 for both statuses (without UFR and with UFR at water meter no. 3) errors in

With UFR in operation, the most significant contribution in measuring water volume by wa‐ ter meter (15.7-0=15.7%, mean value of 30 measurments) was determined at operations at

At steady flow slightly lesser than Qa, UFR efficiency increases from T10 to T30: water meter equipped with UFR type T10 measures for 99.53-84.14=15.39% more water than in status without UFR, while the increase with type T20 is 99.33-68.55=30.78% and with type T30 it is

This conclusion was verified for a single household water supply network by the results of five measurements for each status: water meter equipped with type T10 UFR measured (at flow rates Q2=51.3-51.4 l/h and Q3=5.2-5.6 l/h) maximum 9.89-6.84=3.05% more water con‐ sumption of than without UFR, with type T20 (at flow rate of Q2=56.9-60 l/h and Q3=5.3-5.5 l/h) the most significant improvement was 9.06-4.19=4.87%, while with type T30 (at flow

/h.

/h and Q3=0.0049-0.0053 m3

rates of Q2=55.9-58.5 l/h and Q3=4.9-5.1 l/h) the result is 8.4-0.97=7.43%.

Error in the operation of water meter at steady state flow defined by equation (1) is:

**Figure 6.** Error (G) in the operation of water meter no. 3 at steady state flow in function of flow rate Q3, without UFR and with UFR.

The error in the operation of water meter no. 3 without UFR is bigger than with UFR.

The measurements proved that Qa<0.01 m3 /h is between 0.0052 and 0.0067 m3 /h.

By increasing flow rate Q3 towards flow rate Qa, the influence of UFR operation on meas‐ uring water volume increases: for Q3=0.0013 m3 /h the contribution is 99.59-78.49=21.1%, and for Q3=0.005-0.0052 m3 /h it is 99.5-28.93=70.57%. For flow rates Q3>Qa up to Q3=0.026 m3 /h the contribution of UFR to measuring water volume by water meter is decreasing: for flow rate Q3=0.0067-0.0071 m3 /h the contribution is 37.67-4.07=33.6%, and for Q3=0.0244-0.0255 m3 /h it is 0.47+0.36=0.83%.

Without the UFR in operation, the water meter always shows lower water volume than the real value. With the UFR in operation, at flow rate Q3=0.01 m3 /h, the operation of the wa‐ ter meter is changing: for flow rate Q3<0.01 m3 /h the water meter shows lower volume than the real value, while for Q3>0.01 m3 /h it shows higher value (not exceeding 2.7%) than the real one.

For status Qmin≤Q2≤Qn balancing errors described by equation (3) are:

Error in the operation of water meter at steady state flow defined by equation (1) is:

0 5 10 15 20 25 30

**Q3 (l/h)**

/h is between 0.0052 and 0.0067 m3

/h it is 99.5-28.93=70.57%. For flow rates Q3>Qa up to Q3=0.026

/h the contribution is 37.67-4.07=33.6%, and for

/h it shows higher value (not exceeding 2.7%) than the

**Figure 6.** Error (G) in the operation of water meter no. 3 at steady state flow in function of flow rate Q3, without UFR

By increasing flow rate Q3 towards flow rate Qa, the influence of UFR operation on meas‐

/h the contribution of UFR to measuring water volume by water meter is decreasing:

Without the UFR in operation, the water meter always shows lower water volume than the

The error in the operation of water meter no. 3 without UFR is bigger than with UFR.

without UFR with UFR

/h.

/h, the operation of the wa‐

/h the contribution is 99.59-78.49=21.1%,

/h the water meter shows lower volume than


and with UFR.

m3

real one.

The measurements proved that Qa<0.01 m3

and for Q3=0.005-0.0052 m3

Q3=0.0244-0.0255 m3

for flow rate Q3=0.0067-0.0071 m3

the real value, while for Q3>0.01 m3

uring water volume increases: for Q3=0.0013 m3

ter meter is changing: for flow rate Q3<0.01 m3

/h it is 0.47+0.36=0.83%.

real value. With the UFR in operation, at flow rate Q3=0.01 m3

For status Qmin≤Q2≤Qn balancing errors described by equation (3) are:

**G (%)**

140 Water Supply System Analysis - Selected Topics

**Figure 7.** Error (Gb) in water balancing on the rig in the function of flow rates Q2 and Q3, without UFR (left) and with UFR (right) in operation.

The highest balancing error values for the tested statuses are +0.9 and -16.6%. By increasing flow rate Q2 for both statuses (without UFR and with UFR at water meter no. 3) errors in balancing decrease.

With UFR in operation, the most significant contribution in measuring water volume by wa‐ ter meter (15.7-0=15.7%, mean value of 30 measurments) was determined at operations at flow rates Q2=0.03-0.0385 m3 /h and Q3=0.0049-0.0053 m3 /h.

At steady flow slightly lesser than Qa, UFR efficiency increases from T10 to T30: water meter equipped with UFR type T10 measures for 99.53-84.14=15.39% more water than in status without UFR, while the increase with type T20 is 99.33-68.55=30.78% and with type T30 it is 99.5-28.93=70.57%.

This conclusion was verified for a single household water supply network by the results of five measurements for each status: water meter equipped with type T10 UFR measured (at flow rates Q2=51.3-51.4 l/h and Q3=5.2-5.6 l/h) maximum 9.89-6.84=3.05% more water con‐ sumption of than without UFR, with type T20 (at flow rate of Q2=56.9-60 l/h and Q3=5.3-5.5 l/h) the most significant improvement was 9.06-4.19=4.87%, while with type T30 (at flow rates of Q2=55.9-58.5 l/h and Q3=4.9-5.1 l/h) the result is 8.4-0.97=7.43%.

**Figure 8.** Error (G) in the operation of water meter no. 3 at steady state flow in function of flow rate Q3=Qa without UFR (left) and with UFR (right) type T10, T20 and T30.

**Figure 10.** Error in water meter measuring at Qmin flow during water flow shorter than the time for which the meter

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143

**Figure 11.** Error in water meter measuring at Qt flow during water flow shorter than the time for which the meter was

was calibrated (10 min.) in the function of water meter reading accuracy.

calibrated (12.5 min.) in the function of water meter reading accuracy.

**Figure 9.** Water balance error (Gb) of the tested water supply network without UFR type T10, T20 and T30 (quadrat) and equipped with one of the UFR type (cross).

Error in water meter measuring due to consumption shorter than the time the meter was calibrated for: each measurement was repeated 5-30 times.

Error in Water Meter Measuring Due to Shorter Flow and Consumption Shorter Than the Time... http://dx.doi.org/10.5772/51046 143



calibrated for: each measurement was repeated 5-30 times.

**Gb (%)**

UFR (left) and with UFR (right) type T10, T20 and T30.

142 Water Supply System Analysis - Selected Topics

and equipped with one of the UFR type (cross).

**G (%)**

10 20 30

Q3=5,8-5,9 l/h Q3=5,6 l/h Q3=5,2-5,3 l/h Q3=4,8-4,9 l/h Q3=5,2 l/h Q3=5 l/h

**T10, T20 and T30**

10 20 30

**T10, T20 and T30**

**Figure 9.** Water balance error (Gb) of the tested water supply network without UFR type T10, T20 and T30 (quadrat)

Error in water meter measuring due to consumption shorter than the time the meter was

Q2=51,2-56,9 l/h, Q3=5,4-5,6 l/h Q2=51,4-53,2 l/h, Q3=5,2-5,4 l/h Q2=55,3-58,8 l/h, Q3=4,9-5,6 l/h Q2=58,9-60,3 l/h, Q3=5,3 l/h" Q2=54-60,7 l/h, Q3=4,9-5 l/h Q2=54,3-58,5 l/h, Q3=4,9-5,1 l/h

**Figure 8.** Error (G) in the operation of water meter no. 3 at steady state flow in function of flow rate Q3=Qa without

**Figure 10.** Error in water meter measuring at Qmin flow during water flow shorter than the time for which the meter was calibrated (10 min.) in the function of water meter reading accuracy.

**Figure 11.** Error in water meter measuring at Qt flow during water flow shorter than the time for which the meter was calibrated (12.5 min.) in the function of water meter reading accuracy.

**4. Discussion**

bution is decreasing from flow Qa towards flow Qmin.

out UFR and with UFR enabled specifying the results.

Measurement results confirm and specify the conclusions of tests made in Udine in relation to the contribution of UFR to water meter operation: a) that the most significant contribution is at flow, when water meter propeller is steady (specifically for Qa), and b) that this contri‐

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145

The same conclusion is valid for test results on the UFR contribution at parts of the water supply network. Providing similar water consumption during testings on the test rig with‐

In the case, when consumption time was shorter than the time the meter was calibrated for,

**Accuracy charge During experiment During calibration**

Qt from 1.9 to 12.1 ±2 Qn from 1.6 to 3.2 ±2

Qt from 4.2 to 7.5 Qn from 1.2 to 2.8 1 decilitar Qmin from -25.9 to 50.9 ±5

> Qt from -8.3 to 86.9 Qn from -4.8 to 4.8

**Table 4.** Error ranges of water meter measuring for calibrated discharges in the function of water meter reading accuracy (class B, rated diameter of 20 mm and discharge of Qn=1.5 m3/h), for a duration of 0.5 minutes flow.

It means that during consumption shorter than the time the water meter was calibrated for, measuring by the meter is unreliable in 95% of the consumption shorter than 1 minute. Dur‐

In order to improve water consumption measuring in households, it is necessary to provide conditions for measuring consumption at flow lower than Qmin and duration shorter than the time the meter has been calibrated for. Such conditions may be created in supply pipe‐ lines with water storage tanks in households. Only such systems are appropriate in which

The UFR should be installed on the outlet pipe from the tank to the household. Signalising the start of the UFR's operation may initiate works on eliminating water losses due to leak‐ age on the tap, bathroom battery and the flushing cistern. This way, the use of UFR would

the range of the meter measuring error exceeded the range of permitted errors.

**Reading Dis- Error range (%)**

2.5 centilitar Qmin from -7.4 to 32.1

1 litar Qmin from -100 to 277.4

ing a discharge of 0.5 minutes, the error may be even 277.4%.

serve to protect the interest of the households.

all the water needed in a household flows through this storage tank [19].

**Figure 12.** Error in water meter measuring at Qn flow during water flow shorter than the time for which the meter was calibrated (4 min.) in the function of water meter reading accuracy.

The minimum time at which measuring errors undoubtedly are within the permitted limit is defined for the calibrated flows of the water meter as follows:


**Table 3.** Minimum calibrated flow duration time in the function of reading accuracy.
