Popular Science on Metrology | Talking about Household Gas Meters
Development Trajectory
At the end of the 18th century, coal was used to produce domestic gas. In 1792, the Scotsman W. Murdoch dry-distilled bituminous coal using an iron still and used the resulting gas for household lighting.
In 1812, this dry-distilled gas was first used for street lighting in London. Subsequently, some major cities around the world also adopted dry-distilled gas for lighting.
In 1816, a coal dry-distillation plant was established in Baltimore, USA, to produce gas.
In 1875, hot-heated gas was produced for use as city gas. With gas available in cities, people used the flames from burning manufactured gas for lighting and made gas lamps. As gas consumption increased, it became necessary to meter and charge for gas, initially based primarily on the number of gas lamps and the duration of use.
In 1815, the British engineer Samuel Clegg invented a water-sealed rotating drum gas meter, which was relatively large and used for metering gas delivered to gas plants.
In 1832, Samuel Hill manufactured the first water-sealed rotary drum gas meter in Baltimore, USA. This type of meter primarily calculated gas output based on the number of revolutions of the drum, resulting in a relatively large margin of error.
In 1833, James Pocadas of England invented the diaphragm gas meter, using oil-soaked silk as the diaphragm material. In 1844, Messrs. Croll and Richards of England manufactured a gas meter with two circular diaphragms and two corresponding sliding valves. Several years later, Thomas Glover of England continuously improved upon it, developing it into the widely used diaphragm gas meter we know today.
Working Principle
Diaphragm gas meters operate on the volumetric principle, using a set volume as the unit of measurement. The principle is as follows: A flexible diaphragm divides the metering chamber into two spaces. When the left side is filled with gas, the diaphragm moves to the right, compressing the right space; when the left side is full of gas (one unit volume), the right space has zero gas volume. Then, the right outlet is closed, the inlet is opened, and gas is input. The diaphragm moves to the left, expelling the gas from the left side; when the right side is full of gas (one unit volume), the left side also expels gas (one unit volume). In this way, the metering chamber completes the measurement process for two units of gas volume. To ensure a balanced and continuous gas input and output range and improve measurement accuracy, currently manufactured gas meters all have two metering chambers. When the gas meter is working, the distribution valve is properly connected to the two metering chambers. Gas enters the metering chambers alternately through the distribution valve, which in turn pushes the flexible diaphragm in the two metering chambers to move back and forth, filling them and then discharging them to the gas outlet. The conversion mechanism converts this filling and discharging cycle into a corresponding volume and transmits it to the counter to realize gas metering.
