Calibration vs Bump Testing

Calibration vs Bump Testing, what’s the difference?


Calibration is the comparison of measurement values delivered by a device under test with those of a calibration standard of known accuracy.

A monitor calibration is a “resetting” of the detector’s response against a known concentration of target gas, in a balance of synthetic air or nitrogen. This includes exposing the instrument sensors and allowing the instrument to automatically adjust the readings to coincide with the known concentration of the calibration gas. Or, if necessary, the operator will manually adjust the readings to match the known concentration of the calibration gas.

Bump testing

The “Bump Test” is a quick check that the sensors are responding correctly to a known gas typically within ±10% accuracy.

So, with the “Bump Test” it is up to you to determine if the sensors are working properly by viewing the real-time readings. With the “Full Calibration” the instrument’s electronics determine if they pass or fail. The bump test does not check the instrument’s accuracy or calibrate the sensors. This is where the calibration comes in

Do you know how often you should calibrate your gas monitor and when to carry out a bump test?

If the answer is no, then you need to know that the calibration interval varies depending on the instrument you choose. For example, if you are using the Dräger X-am 2500 Gas Detector, it is recommended that the standard 4 gas monitor (LEL, CO, H2S, O2) be calibrated every 6 months.

If you are wondering how often you should bump test your monitor?

According to OSHA, a bump test of portable gas monitors should be conducted before each day’s use according to the manufacturer’s instructions.

If you need more information or you have any enquiry, please contact us on 02920 759 683 or email our team at

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