A small internal turbine measures the speed of the gas, which is transmitted mechanically to a mechanical or electronic counter. Because the volume of gas is inferred from the flow, it is important that flow conditions are good. Turbine gas meters infer gas volume by determining the speed of the gas moving through the meter. The rotational movement of the crank shaft serves as a primary flow element and may produce electrical pulses for a flow computer or may drive an odometer-like counter. The operating principle is similar to that of a Roots blower. With each turn, they move a specific quantity of gas through the meter. Within the meter, two figure "8" shaped lobes, the rotors (also known as impellers or pistons), spin in precise alignment. Rotary meters are highly machined precision instruments capable of handling higher volumes and pressures than diaphragm meters. Rotary meters Operating principle of a rotary gas meter This shaft can drive an odometer-like counter mechanism or it can produce electrical pulses for a flow computer.ĭiaphragm gas meters are positive displacement meters. As the diaphragms expand and contract, levers connected to cranks convert the linear motion of the diaphragms into rotary motion of a crank shaft which serves as the primary flow element. With the gas flow directed by internal valves, the chambers alternately fill and expel gas, producing a nearly continuous flow through the meter. Within the meter there are two or more chambers formed by movable diaphragms. These are the most common type of gas meter, seen in almost all residential and small commercial installations. Types of gas meters Diaphragm/bellows meters A diaphragm type gas meter, cutaway sketch from 1900 Since then, the vast majority are now placed outside though there are a few exceptions especially in older cities. Gas meters that exist in colder climates in buildings built prior to the 1970s were typically located inside the home, typically in the basement or garage. Several different designs of gas meters are in common use, depending on the volumetric flow rate of gas to be measured, the range of flows anticipated, the type of gas being measured, and other factors. Temperature, pressure, and heating value compensation must be made to measure actual amount and value of gas moving through a meter. Gas meters measure a defined volume, regardless of the pressurized quantity or quality of the gas flowing through the meter. Gases are more difficult to measure than liquids, because measured volumes are highly affected by temperature and pressure. Gas meters are used at residential, commercial, and industrial buildings that consume fuel gas supplied by a gas utility. JSTOR ( September 2014) ( Learn how and when to remove this template message)Ī gas meter is a specialized flow meter, used to measure the volume of fuel gases such as natural gas and liquefied petroleum gas.Unsourced material may be challenged and removed. Please help improve this article by adding citations to reliable sources. This article needs additional citations for verification.
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