Therefore I developed the Excel sheet for the same. In our case we were having 3 boilers B-601, B-605 & B-606. From a standard curve I derived the correlation & put the data in Excel sheet called "Data". Now you can put your pH against phosphate concentration in the corresponding cell. For example say for B-605 you need to put pH on F column as 9.70 against phosphate value of 3.56 in row no 260.
This diagram is useful in identifying the effectiveness of your boiler pH control program. After getting this curve you can have an analysis of Caustic gauging zone, Or Acidic Zone or localized attack / proper system.
Using this sheet we maintained very well pH control system.
So Use this file & improve your boilers health.
To Download the file , just click .... pH-Phosphate Co-ordinated Diagram