Low pH in deionized water ?

[dobit]

We recently sent out our membrane filters (TRISEP-X20)for cleaning and the new vendor installed their loaner membrane filters (different brand)pending the arraival of ours.

All of a sudden the pH of deionized water dropped to 4.5. This is creating lot of problems for our process. I was told that organic compounds on some membrane filters may not be compatible with some resins. Is this true? I need good opinions on this problem.

Thanks, Dobit

 

[GarySCWSVI]

I am not aware of any compatibility problems between the materials of constrution of membranes and ion exchange resins. Give us more detail on your system. pH is very difficult to test on deionized water. The drop may be coincidental to a failure of the DI water system. How are you testing the pH?

 

[RicD]

If your di h2o is 15 megohm or higher...it is dead 7.0 ph. Try pinching some salt into your beaker before running sample of di h2o. The problem with measuring di h2o is the lack of ions...co2 is immediately grabbed lowering ph. Typical ph of 5 is measured fairly soon after grabing sample.