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Posted by Kyle Armstrong on August 18, 2002 at 18:35:34:
In Reply to: WATER TREATMENT posted by Steve on August 15, 2002 at 07:59:32:
: What effect does pH have when using a phosphate treatment??
Generally the higher the Phophate, the higher the pH you are permitted, but that being said there are a whole lot of caveats that go along with this statement.
If you imagine a graph pH (y axis) phosphate (x axis)on this graph there is a control box or target that when you are in corrosion is minimized. The control box is a trapazoid that stretches left to right in an upward fashion. There are four boundaries (walls)to this box. 1) lower pH boundary - to prevent acid phosphate corrosion, this is set based on the 2.8 to 1 molar sodium to phosphate ratio. 2) the upper pH boundary - to prevent caustic gouging, based on 1 ppm free caustic. The upper po4 boundary based on the maximum po4 premitted to prevent excessive vapourous carryover of sodium in the steam. 4) the lower po4 bountary where there just isn't enough buffer in the boiler water.
Hope this helps, if you are stuck, follow up with more questions are I can try and help
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