When do I have to calibrate my gas detector? This is a frequently asked question regarding the use of gas detectors. The frequency of calibration depends on the type of use of the gas detector. It is essential that the user of the gas detector develops a calibration frequency. The user could start with calibrating the gas detector once a week. If after several weeks hardly or no adjustment is needed the user could decrease the calibration frequency to a point where only small adjustment is necessary when calibrating. Finally, the calibration frequency will end up somewhere between 1 and 3 months.
When are exceptional calibration frequencies necessary?
If the gas detector data is used as proof in court, the user should calibrate the gas detector before and after each test to avoid any doubt of an excellent working gas detector. When a gas detector is only used a few times a year, the user should calibrate the gas detector before each use.
What is calibration?
Calibration is done using an internal menu within the gas detector. This requires an exact blend of calibration gas to re-establish accuracy of the sensor or sensors of the gas detector. Calibration ensures the gas detector works accurately. It is important to check the expiry date of the calibration gas before starting the calibration. Further, it is essential to use a calibration gas with precisely the gas concentration or gas concentrations necessary for a specific brand and type of gas detector. Before calibration, the gas detector should have a zero. Zeroing the gas detector should take place in a room with clean air or by using a Zero Air Cylinder. After zeroing the gas detector, the gas detector can be calibrated. If the gas detector fails calibration, a service company or the manufacturer should be contacted. Read more about how the calibration of gas detectors work in our previous blog.
What is a bump test?
For users who bump test their gas detector before each use, the calibration frequency can be extended to 3 to 6 months when the gas detector successfully pass the bump tests each time. A bump test means holding the gas detector up to a level of calibration gas just long enough to bring it into alarm. With this method, only sensor functionality is ensured. For carrying out a bump test calibration gas is needed. A bump test checks that a gas detector works at all. It is to be advised to bump test a gas detector and to check the alarms before every use to be sure the gas detector is operating correctly. If the gas detector fails a bump test, it should be recalibrated. If the gas detector fails calibration, a service company or the manufacturer should be contacted.
In the shipping, the regulation is that gas detectors should have service by an authorised company once a year. On land, gas detectors should have service every 6 months.
What is annual service of a gas detector?
Besides self-calibration, the gas detector should always have annual service. Annual service of a gas detector is the inspection and (if necessary) repair and calibration of a gas detector by an authorized company once a year. In the shipping, the regulation is that gas detectors should have service by an authorised company once a year. On land, gas detectors should have service every 6 months. The authorised company in the first instance inspects the gas detector for proper operation. If a gas detector has a defect, this should be repaired. An error is often caused by a defect sensor or more defect sensors. After inspection and (if necessary) repair the gas detector will be calibrated with calibration gas and will be provided with a calibration certificate with a validity of one year or 6 months (depending if the gas detector is used in the shipping or is used on land).
Further, it is recommended to bump test or calibrate the gas detector when it is suspected that the gas detector has been subjected to any condition that could damage the gas detector. For example sensor poisons, high gas concentrations, extreme temperature, mechanical shock, etc.