The gas meter has the same principle as the ancient locomotive, relying on the pressure of gas to do external work and pushing the roller counter to count. How to do it specifically? The cylinder and piston mechanism in the locomotive have been greatly simplified by replacing the cylinder with a "bellows" and the piston with a "membrane". The so-called "bellows" is nothing more than an empty box made of metal, with two halves joined together and a soft and airtight film sandwiched between them.

From the outside of the gas meter, you can only see a scroll wheel with numbers inside the small glass window. There are also seven digits on the scroll wheel, with the first four digits of the decimal point being black and the last three digits being red. The fuel used for people's daily cooking has been transformed from conventional energy sources such as wood and coal, which are seriously wasted and polluted, into clean energy sources such as natural gas and gas, and even electricity. Here, the gas meter is about to play its role. Its automatic accumulation function allows those who use natural gas or pipeline gas to easily know how much gas is used, so that they can pay according to the cubic meters of gas consumed each month.