Have you ever heard that “The solution to pollution is dilution”? This little aphorism is usually stated as a sort of inside joke, although it is public policy for radon in residences. We saw this principle in action when home builders affected by the Chinese drywall disaster would sometimes open all windows while the homes were being tested for reduced sulfur compounds off-gassing from the wallboard.
As to detector tubes, many years ago, one of our sales reps was working on an ammonia monitoring application in the poultry industry. Chickens are extremely sensitive to this gas, which accumulates in chicken coops and poultry houses. This situation worsens in the winter, when ventilation becomes more expensive, and is sometimes less rigorous than it should be.
The sales call was in the early fall, and temperatures had not yet dropped too much at this location on Maryland’s eastern shore. The indoor ammonia was detectable by odor, although it was not overwhelming. And, the potential customer also took a detector tube sample, which indicated a surprisingly low concentration.
The detector tube pump was a bellows style unit, that should be regularly leak-tested per this procedure. Our rep was suspicious of this low reading, and suggested that the pump should be leak tested right then and there. The above cited test procedure states that upon inserting an unbroken tube into the pump, and then squeezing the bellows and relaxing the grip, “[T]he position of the pump body should not change within 1 minute.”
However, during this test, the pump completely re-inflated in less than five seconds. That’s why the reading was so low!
Check here for how to leak test a piston-type detector tube pump.
If you are suspicious of readings on any gas detection system, contact us.