A gas detector is a vital part of PPE and when used correctly may save your life if you find yourself in a hazardous environment. Gas detectors is not a widely know field so many users don’t understand how they work and the hazards associated with incorrect use. Just because it was calibrated last week, doesn’t mean it is working properly today.
The toxic sensors are usually electro-chemical cells which means they contain a chemical that will react with the gas to be detected and generate an electrical signal to indicate the level of gas detected. However if the unit is not properly serviced replacing the sensing element, the chemical in the sensor will be consumed by the sensor, it stops measuring gas and in some cases may not generate a fault alarm. In this circumstance the user is not protected by the gas detector because it will display no gas present even when there is.
So now understanding the way a gas detector works we can adopt strategies to keep the workforce safe. We know that just because your detector worked yesterday it doesn’t mean it is working properly today, so the best way to check it is working properly is to apply gas, this process is known as bump testing. With multi-gas mixtures available now with 4 or 5 gases in one cylinder, it can be a very quick process to simultaneously check all sensors. The typical time it takes a detector to respond to all gases is about 20 seconds. To be truly safe, a gas detector should be bump tested every time before use. In reality companies and authorities set their own guidelines and often agree on once per day as AS/NZS 60079.29.2:2016 recommends.
The consumable cost of the gas is only around $1.50 per bump test but if that saves one life, it has to be worth it, especially if it is yours!
People often confuse bump testing with calibration, they are not the same thing. A calibration is the process to accurately set the levels of the sensor and must be done in a controlled environment. It takes time for the sensors to settle to an accurate level so typical duration of a calibration is 60 to 90 seconds. A bump test is just a quick check the detector is working with a typical duration of 20 seconds. When a bump test gas mix is applied If you applied all you really want to see is all gases go into alarm mode, it doesn’t matter about the value they are showing. With docking stations available for gas detectors that charge the battery in the detector and calibrate multiple units at once.
To test and maintain accuracy gas detection systems require regular testing and calibration. GDA can provide a complete line of calibration equipment to calibrate all of our gas sensors and detectors. The gas mixture in calibration gas cylinders are N.I.S.T. certified with ISO 17025 approval you can be confident that you will receive gas with the highest accuracy levels.
If you have any questions or queries please contact us.