How Often?
If your unit indicates a fault it will generally require service which can include an accredited calibration and maybe even new components. Often this will require testing with specific levels of the target gas.
Most manufacturer's recommend formal, documented calibration of instruments at least every six months or more often in some applications. There is similar guidance and requirement from standards such as IEC60079/AS/NZS60079 which requires users to set up and monitor a gas detection program, including trained personnel to regularly check, monitor and document equipment and personnel and also to follow manufacturers recommended intervals for calibration and regular testing.
