Do I have to set the gas detector to zero each time I switch it on or off?
Do portable gas detectors need to be "zeroed" every time they are turned on and used. This is actually a good question, so what exactly is the zeroing step?
As a standard procedure, we train instrument users to perform four basic steps in clean air each time the instrument is opened:
1. Confirm battery level
2. Zero adjustment
3. Ventilation test
4. Clear Peak
Do you need to zero? There are several points to note:
1) The key to air zeroing is to know that you are in clean air. Unless you know you are in a clean air environment, you should not zero the instrument. Zeroing the instrument in the polluted atmosphere may lead to confusion of readings, and may even mask the readings of potentially dangerous gas concentrations.
2) If zero is set, but the surrounding environment is near a fire or in a smoke filled area with no clean air, you should use zero air (compressed air to remove impurities) to establish a standard for your detector. Zero air will not damage the functionality of your detector or interfere with the sensor.
In an unclean air environment, if the instrument is turned on and the combustible gas and other gas sensors read 000, while the oxygen sensor reads 20.9, what is the purpose of zeroing the gas detector? Assuming that your gas detector did not deliberately mask negative readings (Industrial Scientific's instruments do not do this), it is not good to zero at this point. So, if you turn on your instrument and the reading is normal or within your acceptable range, don't waste time completing the zeroing process.
