The inconvenient truth about gas monitors is that they need to be regularly calibrated. It is simply impossible to know/confirm if a monitor is detecting properly without a calibration.
Do I Really Need to Calibrate?
Yes. Although OSHA doesn't offer up its own frequency recommendations, they make it clear that calibration is required. OSHA says, "Proper maintenance and calibration of the instruments ensures their accuracy in detecting worker exposure to harmful gases in the workplace."
But they aren't completely silent about frequency. They just defer to the manufacturer's requirements: "Follow the manufacturer's recommendations with regard to calibrating the instruments."
In effect, OSHA's position makes the manufacturer's requirements about calibration "the OSHA standard" for that particular gas monitor. The manufacturer's requirements are, of course, usually found in a particular monitor's instruction manual or a manufacturer's bulletin.
It might be helpful at this point to actually look at an example of a manufacturer's calibration recommendations. GFG's calibration bulletin states the following:
Any incidents or exposure to contaminants that might adversely affect calibration should trigger a functional (bump) test or calibration check before further use.
A full calibration should be performed any time the instrument fails a functional (bump) test or calibration check before further use.
Even if the instrument passes all functional (bump) tests and calibration checks successfully; a full calibration should be performed at least once every six months.
This is essentially the same as every other manufacturer. They want to be as strict as possible, yet not too over-bearing. So here GFG recommends a bump test before each use (as all manufacturers do). They then determine a calibration schedule based on a failed bump test. If the monitor fails a bump test, it needs calibrating. And regardless of everything, do not go longer than "every six months" between calibrations.
Easiest Way to Calibrate
If you bought a monitor from us, we are likely sending you calibration reminders via email. Hopefully, you've now been convinced that you really do need to calibrate your monitor/s.
There are two ways to calibrate. (1) You can buy the correct calibration kit for your meter. Calibration kits are usually around $425. It would allow you to both calibrate and bump as often as you wish. (2) You can send the monitor back to us. We currently charge $85 for a calibration. You get a calibration, a calibration sticker, and calibration certificate.
Either way, we are here for assistance and guidance.