Answer / narendra mishra

You have to keep ph slightly more than 7 so that if Ph gets down below 7 then we will have some time to raise it above 7.if we keep it at 7 & when it gets down to 6 then it will immediately become acidic.

Answer / arun kumar

Least corrosion point pH 8.5-9.5. For Drum type boiler if we use boiler chemical Trisodium phosphate this chemical not react with scale(calcium carbonate) at neutral pH. If boiler pH acidic means corrosion & Silica carryover also takes place

Answer / er_nillu

According to Le-chatelier's principal the equillibrium of reaction depends up on pressure and tepmperature at which it is going to takes place.Therefore at neutral point of hydrogen ions concentration (which is responsible for pH) shifts from 7 (7 is the value of pH at atmospheric condition) slightly 8 to 8.5. Simillerly it will shift below 7 at temp below atm temp.

Answer / alok bhattacharya

We need to mix scavenger in feed water in order to make it oxygen free which helps boiler from corrosion. Phosphate dozing is primarily done for this purpose and this raises PH value and usually maintained around 9. Moreover phosphate dozing helps to make magnetite layer which inhibit corrosion.
Acidic water is prohibitive in boiler for above reason, i.e.
Ph below 7.

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