Gas Fitter Practice Test

A bellows gas meter is also known as what?

1. Down stream displacement meter

2. Up stream displacement meter

3. Pressure displacement meter

4. Positive displacement meter

The correct answer is: Positive displacement meter

A bellows gas meter is commonly referred to as a positive displacement meter. This type of meter measures the volume of gas flowing through it by physically displacing a diaphragm or bellows with the incoming gas. The movement of the bellows is directly proportional to the volume of gas, allowing for accurate measurement and clear readings. Positive displacement meters operate by dividing the gas flow into discrete volumes or "packets," which are then counted to determine the total volume used. This characteristic differentiates it from other types of gas meters, like orifice or thermal meters, which measure flow based on pressure drop or temperature change rather than moving a mechanical component. The term positive displacement reflects this direct correlation between the movement of the mechanical parts inside the meter and the measurement of gas volume, ensuring high accuracy under various flow conditions. In contrast, the other terms do not accurately describe the fundamental operation of a bellows gas meter or misrepresent its measuring mechanisms.