A bellows-type gas meter is the most popular type of device for measuring the volume of gas flowing through it. It is used in cases where a provider of gas needs to bill an individual user or small enterprise that consumes it. The design of this type of gas meter works as follows: two bellows alternately fill with gas and transfer their reciprocal motion through a servomechanism. This motion is converted to a rotary movement of the drum counter mechanism, which is used for metering the fuel consumption. The limited throughput of the device prevents it from being used for measurements on an industrial scale. This can be resolved by using turbine gas meters, in which a moving piece (usually a small fan) is propelled by the difference between the gas pressure upstream and downstream of the gas meter. Manometric gas meters are also used in industry: they have a n orificein the flowing stream of fuel, causing a measurable difference in the pressure between the inlet and outlet of the device.
The bellows-type gas meter presented here was built by the Polish PoWoGaz company – Poznańska Fabryka Wodomierzy i Gazomierzy – which had been in operation without interruption since 1925 when it was established as the Water Meter Repair Workshop of the Poznań Water Supply Network. Over the years the enterprise was enlarged and the scope of its production extended to offer devices related to water pipelines, gas supply and heating. The high quality of products is evidenced by the company receiving a Gold Medal at the National Exhibition in Poznań in 1929. Now, after ownership transformations, this Poznań-based manufacturer is part of the Apator group.
Interesting fact: A gas meter monitoring the flow of gas is not the only type of device that allows a provider to bill consumers of the fuel. There were also coin-operated devices, which only opened the gas valve after a coin or a token was inserted which allowed a fixed quantity of gas to be received. There were also special coupons that made it possible to pay for a certain quantity of gas in advance.

References:
Gazomierze w sieci virtual exhibition, Wirtualne Muzeum Gazownictwa, https://wmgaz.pl/wirtualne-wystawy/gazomierze-w-sieci (Accessed: 9.05.2021).
Świat się zmienia, my to widzimy, a presentation by Apator Powogaz, Poznań 26.10.2012, available at: https://www.kierunekwodkan.pl/Resources/art/5344/bmp_508e782577d29.pdf (Accessed: 9.05.2021).
A price list of Apator products 2017, nr 02/2017, available at: https://hvacpr.pl/cenniki/zalaczniki/40 (Accessed: 9.05.2021).