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Q & A: gas in deionized water

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Most recent answer: 11/02/2014
Q:
I have been using DI water for some leak testing. I have found that when I leave the DI water in clear PVC tubing, similar to IV tubing in the hospital, I get bubble formations all thought the tubing. Why would this be happening if DI water has most of element ions/gases removed?
- Scott (age 25)
Salt Lake City, UT
A:

Standard deionized (DI) water has had the ions removed by flowing through an ion exchange resin. This rosin grabs most dissolved ions (Ca++, Cl-, etc.) and releases H+ and OH- to replace them. These mostly recombine to form H2O, leaving just the usual low background level of H+ and OH- found in pure water. The resin does not generally grab non-ionic solutes, such as N2 and O2, the main ingredients of air. So the DI water still has dissolved gases. Depending on temperature and pressure, these may tend to come out of solution in your tubes.

Mike W.

posted without vetting until Lee returns from the Serengeti 


(published on 11/02/2014)

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