Allowances must be made if other gases are being measured. Bump Test and Calibration Two terms that are related are the bump test and calibration. A bump test involves exposing a monitor to known gases, allowing it to go into alarm, and then removing the gas. This test is also known as a field test. If the monitor does not respond sufficiently to the bump test, then a field calibration should be performed.
Calibration determines if the monitor responds in an appropriate fashion.
This is done by exposing the monitor to a known quantity of gas and ensuring that the sensors responded correctly. As the sensor gets older it becomes less sensitive, and calibration electronically raises the value that the sensor displays. When a sensor fails, it cannot be electronically brought up to the correct value. Calibrations used to be very difficult but with the new monitors and multi-gas cylinders, it is relatively easy, depending on the manufacturer. The regularity of calibration is subject to great debate, as some response teams calibrate daily, others every six months.