How Do you Calibrate a Gas Meter?

Gas meter calibration system has become an essential nowadays. Numerous methods are applied for performing gas meters’ calibration.

Bell Prover: This is actually a calibrated vessel with well-known volume characteristics. It is often used as a primary standard. The Bell Prover provides a certain volume to the gas meter under test and thus a direct comparison between the meters' reading and the volume’s value can be performed. This method is mainly used for calibrating small domestic and diaphragm meters.

Gravimetric method: A very precise weighing scale is used to define the amount of gas that actually flows through the meter during the calibration procedure. This method is measured to be very accurate.

Test Bench: It is a comprehensive system which uses master meters as reference standards. The same amount of volume flows through the master meter and the gas meter under test, and the two meter readings are compared to each other. This Gas meter Calibration method is widely used by many calibration laboratories all over the world. Depending on the size of the master meters, high flow rates can be achieved and very large gas meters can be calibrated.

Before continuing with the analysis of the Test Bench method of calibration, it is vital to give some information about the metrological characteristics of the most common types of gas meters. The air enters through the filters and flows through the master meter. The flow is adjusted via the control valves and the speed of the fan. The air passes through the meter under test and returns to the room exiting from the fan. A temperature and a pressure sensor are placed on each meter (master meter and meter under test). The test bench must have the capability to monitor the pressure drop at the meter under test as well as leakages at any part of the installation.