Guide by Vistec Gas Detection. Last updated October 2026.
How often should gas detectors be calibrated? The short answer is as often as the manufacturer says, and sooner if conditions demand it. This guide sets out typical intervals for portable and fixed detectors, the difference between a bump test and a calibration, and the records health and safety leads should keep.
A bump test is a quick functional check. The detector is exposed to a known gas concentration above its alarm points to confirm that the sensors respond and the alarms go off. It does not change any settings.
A calibration adjusts the detector so its readings match the true gas concentration. A certified test gas of known concentration is applied, and the zero and span are set. Honeywell’s technical guide describes calibration as the step that makes sure readings truly represent the gas in the air. Both matter: the bump test catches a failed sensor today, and calibration keeps readings accurate over time.
Always follow the manufacturer’s instructions for your model. As an example, BW Technologies by Honeywell says its GasAlertMicroClip detectors should be calibrated before first use and then at least once every 180 days, depending on use and exposure to poisons and contaminants. Honeywell’s general guidance is that portable detectors are usually calibrated twice a year, more or less often depending on the application.
Many modern portables, including the BW range, can be set to warn when calibration is due and to stop the user carrying on until it is done. Disposable single-gas detectors are the exception: they are not calibrated, but still need bump testing.
BW Technologies by Honeywell recommends a bump test before each day’s use, and Honeywell describes a daily bump test as best practice because it is the only way to know a portable detector is working. If a detector fails, it should be calibrated, and if it still fails, taken out of service.
For confined spaces, the HSA’s Code of Practice for Working in Confined Spaces says monitoring equipment needs to be calibrated before use, thoroughly examined and maintained to the manufacturer’s instructions. See our confined space gas monitors for suitable instruments.
Fixed systems should be calibrated when installed and then checked and re-calibrated at the interval the manufacturer sets. Honeywell’s guide points to EN 60079-29-2 for flammable gas detectors and suggests that checks may start at weekly intervals and be extended as operational experience is gained.
In practice, most sites put fixed detection on a planned service schedule. Our maintenance contracts do this for you: the customer database flags a month in advance when a service is due, so the visit is booked at a time that suits you.
Some conditions call for checks sooner than the standard interval:
The HSA confined spaces code says reports of thorough examinations and records of calibration should be kept. Good records show each detector’s serial number, location, date, test gas used and its certificate, readings before and after adjustment, and who did the work. Honeywell notes that datalogging is often required by legislation or by insurers.
Use certified, in-date test gases of the right concentration for every calibration. We provide gas detector calibration with certified test gases and issue calibration and compliance certification, on equipment from many manufacturers, not only the brands we sell.
Very little time. In Honeywell’s manual method, a short burst of test gas of about three seconds is applied through a test cap, the alarms should sound, and they clear once the gas disperses. Automatic test stations can also log the result.
Yes, with the right test gas, equipment and training. BW advises calibrating only in fresh air in a safe area. Fixed detectors in flameproof enclosures may need the power isolated and a permit before they are opened, which is why many sites use a service contract.
Do not use it. Calibrate it and test again. If it still fails, the sensor may need replacing, and the detector should stay out of service until it passes.
Only if the manufacturer’s instructions allow it for your detector and conditions. Honeywell says portable detectors are usually calibrated twice a year, and BW sets a maximum of 180 days for its MicroClip range. Harsh environments can justify shorter intervals.
An accurately calibrated standard gas mixture of the target gas, so the zero and span can be set correctly. BW, for example, factory calibrates its flammable sensor on 50% LEL methane, and Honeywell advises that calibration gas for electrochemical sensors should use air as the main component. Use certified test gas and keep the certificate with your records.
No. Disposable single-gas detectors are not calibrated, but Honeywell still recommends bump testing them, because a bump test is the only way to confirm the sensor responds to gas.
We calibrate and service fixed and portable gas detectors from many manufacturers, with certified test gases and full records. Call 01 289 7720 or email info@vistec.ie.
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