Gas detectors keep you and your workforce safe from the often invisible threat of gas hazards. They often mean the difference between life and death, but they are only as good as their previous calibration.
Why Should You Calibrate?
The most common failure in catalytic sensors is performance degradation caused by exposure to certain poisons; such as the gases they’re installed to protect you against. The only way to protect against this is to schedule regular maintenance and calibration to check your system is working as expected.
Harsh environments such as temperature extremes, humidity, contaminant exposure, gas exposure and age will all affect how your detector responds to varying gas concentrations.
Industry regulations also require gas detectors to be calibrated regularly. You will also need to keep records to show that they have been calibrated, but these can also prove valuable. If you have a problem later down the line, you can refer back to your maintenance notes for troubleshooting.
How to Calibrate
Gas monitoring systems should be calibrated on installation, and then checked and re-calibrated as part of a regular maintenance schedule.
Calibrating is a two-part process, exposing the sensor to gas and zeroing the sensor in ‘clean’ air. For the first part, the sensor is exposed to a certified concentration of gas for a recorded length of time. This will verify that the sensor is providing accurate readings of gas detection.
Zeroing sets the sensor to recognise the environment’s ambient air as clean air. This means that there are no other gases present that are relevant to that sensor. For zeroing to work, the ambient air must be clean; if the air is contaminated, the sensor will provide inaccurate readings. In this case, the sensor will need zeroing in a zero-air cylinder.
Bump testing requires less time and gas than a full calibration, so is more efficient to do more frequently. At a minimum, your monthly maintenance schedule should include a bump test. If the system fails or it’s been six months since the last test, you should perform a full calibration.
A bump test briefly exposes the sensor to gas, verifying that the sensor is responding and the alarm is working.
Other Maintenance Tasks
Monthly maintenance on your gas sensors is the perfect time to inspect each device for wear and tear that may affect its performance. Check for tampering, damage to the housing, loose screws or wires, as well as a buildup of dust inside and around the enclosure.
Frequency of Calibration
How often you have to calibrate your sensors will depend on the environment and the supplier recommendations. It is also advised to carry out a risk assessment to confirm that the frequency is adequate for your workplace conditions.
If the calibration of your equipment isn’t already an integral part of your maintenance schedule, it should be. Gas detectors are there for your safety and the safety of others in the workplace; it could save lives!