A bellows gas meter is also known as what?

A bellows gas meter is correctly identified as a positive displacement meter because it measures the volume of gas passing through it by mechanically displacing a specific amount of gas with each cycle of the device. In this type of meter, the movement of the bellows directly correlates to the amount of gas flowing, allowing for an accurate measurement of volume based on the physical displacement of gas.

This method utilizes a bellows mechanism that expands and contracts with the flow of gas, effectively capturing discrete volumes. The positive displacement feature is critical in applications where precise volume measurement is required, making it ideal for residential and commercial gas metering.

The other terms may relate to different types of gas measurement systems but do not apply specifically to the bellows meter. For instance, upstream and downstream displacement meters refer generally to their location in a system rather than the specific operational method of a bellows meter. Additionally, 'pressure displacement meter' is not a standard term used to describe this mechanism. Thus, the designation as a positive displacement meter accurately reflects its operational principles and functionality.