Below is an extract from HSE guidance on gas detectors (flammables) 42 The frequency of the function checks will depend on the manufacturer’s recommendations. For portable gas detectors, these should include checking: ■ that a zero reading is obtained in a clean atmosphere away from known sources of detectable gas or vapour; ■ for a response to a known flammable vapour; ■ the battery charge level is adequate for the job; ■ the level of any other reservoirs (eg hydrogen in a flame ionisation detector) is adequate; ■ the logging period (if datalogging is required) to ensure all datapoints over the required duration of measurement can be stored in memory. Phil

check the manufacuturers documentation provided with the gas monitor, you should find the required information there (often in small print).