Natural Gas Flow Measurement
In our Sage-In the Flow blog, we routinely discuss applications for thermal mass flow meters because that is what we manufacture at Sage. Our meters serve a wide range of applications; however there are many other meters that excel in other applications. For this reason, I will present a simple series on different natural gas flow meter types beginning with the diaphragm gas meter.
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Diaphragm Gas Meter
The diaphragm gas meter is one of the most common and oldest natural gas meters. The development of this device in the 19th century was pivotal in the natural gas industry’s success as it created a reasonably priced way to charge the end user for their energy use. Diaphragm meters are found mostly on residential properties and light commercial buildings. This type of meter measures the quantity of natural gas the user consumes so that the gas distributor can bill for it.
Positive Displacement Meter
The diaphragm gas meter is a positive displacement meter, which is also known as a PD flow meter or volumetric flow meter.In this case, the gas flows into a meter inlet or chamber, which has an oscillating diaphragm and contains a known capacity of the gas. The section fills and empties the gas and with each cycle the volumetric flow rate is determined.
Diaphragm meters are relatively inexpensive offering a low cost way for billing measurements for utility companies. They have a long life expectancy. For example, the old Sprague meter shown is around 30 years old and still in service. Rotary meters or newer smaller diagram meters commonly replace these older, well served meters, and many times include AMR (automatic meter reading) systems which allow for remote meter reading.
The main disadvantages of diaphragm gas meters stem from the meter having moving parts. For this reason, they require periodic maintenance, and the gas cleanliness should be considered when using them. The gas meters are usually used in smaller pipes and at relatively low flow rates. While this meter type is accurate for volumetric flow, pressure and temperature compensation are needed to achieve mass flow.