Page 46 - Occupational Health & Safety, April 2018

GAS MONITORING
Are Poisons and Inhibitors Lurking in Your Workspace?
Just because a poison or inhibitor wasn’t applied directly to the instrument doesn’t mean that it may not have been exposed to something while in a tool box, storage locker, or anywhere else gas detection equipment may be stored.
BY RYAN THOMPSON
The sensors inside your personal gas detector are meant to be exposed to toxic, corrosive, and explosive gases, but that doesn’t mean they are infallible. Chemicals and vapors from everyday cleaners and lubricants and specialized chemicals can all act as poisons or inhibitors to differ- ent sensor types. One of the most negatively affected is the catalytic bead LEL sensor. Having a catalytic bead LEL sensor in your personal gas monitor is standard in many applications, so being aware of what can act as a poison or inhibitor can be the difference between a fully functioning monitor and one that may not have the ability to alert you when in the presence of com- bustible gas.
Although it is one of the most common types of LEL sensors, the way in which a catalytic bead LEL sensor detects gas is one of the main reasons it is so susceptible to poisons and inhibitors. Internally, a cat- alytic bead sensor is going to burn the gas that comes in contact with the bead and detect a change in tem- perature. This change in temperature is what is then translated into the reading you see on your screen. When poisons and inhibitors come in contact with this bead, they can completely prevent the gas from
burning, or may prohibit the bead from burning as much as it would have, which in turn, can prevent a readout from being available on your screen. Poisons and inhibitors can have a similar affect, but the way in which they affect the sensor and the sources they come from are different.
40 Occupational Health & Safety | APRIL 2018
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Some of the most common poisons are silicone- based products, lubricants, gas additives, lead, and sulfur compounds. As soon as an instrument with a catalytic bead sensor is powered on, that bead starts to heat up. If any of these poisons come in contact
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