Depending on the number and placement of gas detectors in your facility, you might be looking at the task of calibrating them as never-ending. It is true, calibration can be time consuming, especially if it is a large area populated with multiple fixed location sensors with different gas types - some near the ceiling, others near the floor and still others somewhere in between. However, it is a task the needs to be done and dedicating the time to calibrating them all at once is the optimal and responsible course of action. Having some sensors calibrated and others not on a job site leaves room for inaccuracies and poses a potential danger to workers and the public.
How long it takes to calibrate all the sensors will depend on the experience and training level of the person doing the calibration, what type of equipment is used and the number of sensors in the facility. Trained technicians can calibrate up to two different types of gas sensors at one time, which saves labour time. Taking on that challenge is not recommended unless the technician has the equipment, training and experience. Calibrating one sensor at a time may take a little longer, but can be easier for the inexperienced service technician and the end result is still a correctly functioning gas detection system.
Monthly bump testing of sensors is recommended in particular for sensors that are monitoring for gases that pose a serious health and safety risk when they leak, such as Ammonia, Chlorine, and Ozone. A log book must be kept to detail date, time and confirm bump testing results. It benefits the user to bump test all gas sensors in their facility. When bump testing Ammonia, in particular, use only a concentration of span gas just higher than the low alarm set point. Ammonia sensors are consumable and their life span is often measured in “ppm hours”. Using a high concentration of NH3 span gas to bump test will shorten the life of an Ammonia sensor.
How do you know if you are getting a correct reading from the unit?
The only way to guarantee that an instrument will detect gas accurately and reliably is to test it with a known concentration of gas. Exposing the instrument to a known concentration of test gas will show whether the sensors respond accurately and whether the instrument alarms function correctly. Keeping a log and verifying the accuracy of readings on a daily basis for a trial period will reinforce your confidence that the unit is performing correctly.
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