Oil Field Engine News

Gas-ometer


| November 2005



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A wet gas-ometer showing the operating rod (empty position) bolted to the center of the diaphragm indicating no gas pressure.

This month, guest writer Harold Keller has written an interesting articl­e on gas-ometers. Harold brings with him a vast amount of firsthand oil field experience and many years of exposure to oil field engines.

Gas-ometer: History, Setup, Operation and Maintenance

A gas-ometer (not gas-o-meter) is a primitive but efficient device used to regulate natural gas pressure for an engine. The gas-ometer also serves as a volume tank. There are two types of gas-ometers, wet and dry. Both work on the same principle, and both have their advantages and disadvantages.

The dry gas-ometer has a cast iron body shaped like two deep skillets, with the top body being upside down on top of the bottom one. Clamped into the flange where the two pieces join is a rubber diaphragm separating the two. An operating rod is bolted to the center of this diaphragm, which extends up through a hole in the top iron. This rod is linked to an ordinary stop, and gas pressure entering into the bottom of the gas-ometer raises the diaphragm and closes the stop. The gas then exits out the bottom iron.

When the gas is initially turned on, the pressure raises the diaphragm and the linkage closes the stop. When the gas is turned on at the engine, the pressure and diaphragm drops slightly, opening the stop a little, to allow a little more gas to enter the gas-ometer. As the engine settles down to operating speed, the gas-ometer moves just a little, opening the stop just enough to supply the required amount of gas.

The advantage of a dry gas-ometer is that it doesn't require any liquid for it to operate. The disadvantage is the limited life of the diaphragm. As the gas-ometer ages, the constant flexing of the diaphragm will eventually cause it to crack. When this happens, the gas pressure will leak through, escape out the top hole and fail to raise the stop linkage. This will increase the risk of fire, waste gas and increase the pressure at the engine, possibly causing it to run too fast if not equipped with a governor.