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Tech Tips

Cl2 Testing

(EPA Method 26/26A) at a high SO2 Source

When testing for Cl2(or Br2) at a location with high SO2 emission, the SO2 gas will pass through the H2SO4 impingers in the sampling train and end up in the NaOH impingers lowering the pH of the solution and thereby reducing the effective ability of the reagent to adsorb Cl2gas.

This is because SO2, like Cl2, is an acidifying agent but unlike the halogen gases, SO2 is a reducing agent as well.  By adding a small amount of H2O2 to the H2SO4 impingers you can take advantage of this chemistry to effectively knock out the sulfur gases in the
H2SO4 impingers but without adversely affecting the halogen gases.  Usually 3-5 mls of 30% H2O2 is enough to do the trick for most sources.
[We are currently in the process of obtaining a statement of technical opinion from the EPA authorizing the use of this procedure.  Many state agencies, however, have already accepted this modification step.]

SO3 Testing (EPA Method 8)

For testers who have concerns over the validity of SO3 test results, ask us about the possibility of performing the analysis by ion chromatography.  Matrix effects from many sources can interfere with Method 8 titration analyses.  Ammonia injection is most often the culprit but it isn’t the only one.  Regardless of the problem, ion chromatography can almost always resolve interfering issues with this analytical method.  This alternative approach can be utilized for H2SO4 Mist as well as SO2.

[We can get authorization from most state agencies to perform chromatography on Method 8 field samples in lieu of titration but an OK is typically required prior to testing.]

 

…. more tips to come