**Table 3.**

*A typical "standard" formulation for a chromate product.*

#### *Water Chemistry*

In most hard waters, the typical O:P ratio is 2:1, whereas in lower hardness waters it is 3:1. Typically, the total unfiltered O-PO4 <sup>3</sup><sup>−</sup> reserve is at the concentration of 10–15 ppm. Some "stabilized phosphate" programs contain zinc, which may also be operated at higher pH levels. A formulation for a steelwork or fertilizer plant is shown in **Tables 4** and **5**, and the pH value of the cooling water is 6.5–7.0, perhaps up to pH 7.5.

This program formulation will tend to be dosed continuously to achieve a total phosphate reserve in the recirculating cooling water based on calcium hardness (as ppm CaCC3) as shown in **Table 6**.
