Due to the need for gas supply companies to charge for gas on an `as used' basis, each and every household is fitted with a gas meter. This gas meter records the usage of gas by the consumer over a period of time. Prior to billing, the gas company will `read' the meter either by a `meter reader' travelling from house
to house or by electronic feedback mechanisms.
The gas meter consists of two diaphragm chambers. They both have flexible membranes which are filled and emptied sequentially. Their motions are transferred by levers to slide valves, which govern the flow of gas to and from the membranes. There are also other levers, that perform the task of operating the index drive shaft to rotate the counter which displays the number of `units' of gas used for billing purposes.
