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Title: Domestic Meters
Author: J. R. Stevenson
Source: 1966 Southwestern Gas Measurement Short Course (Now called ISHM)
Year Published: 1966
Abstract: A gas meter provides a means of distributing the cost of gas among users on a fair and equitable basis. To do this, the meter must have a sustained accuracy over a long period of time. In the case of Domestic Meters, it must have the ability to measure the smallest loads such as, pilot lights, which use gas continually, as well as the maximum load which is required intermittently to provide gas for heating the home, cooking, heating water, etc. Positive displacement meters have been used for many years to meet these demands. At the present time, Positive Displacement Meters having either three or four chambers are being used. Our domestic meters are of the four-chamber design. (See Figure 1). Figure 1. The flexible members that define the four chambers are two roll-type diaphragms. The material for the diaphragm is a neoprene-thiokol rubber coated fabric that is resistant to the milder oils. For severe operating conditions, a special material is available. The neoprene diaphragms are also satisfactory for use at extremely low temperatures. This means that a temperature compensating meter uses the same diaphragm as the standard meter therefore, a special inventory of temperature compensated diaphragms is not necessary. The diaphragm is truly the heart of the positive displacement meter. First of all, the motivating force to rotate the meter comes directly from the difference in pressure across the diaphragm. Secondly, the measured volume of gas per revolution of the meter is defined by the diaphragm. All the other meter parts are auxiliary units to aid in its work.