Oil Field Engine News



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

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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.

The wet gas-ometer is made up of two sheet metal cans. The top can is slightly smaller and works inside the bottom one. The bottom can is filled with a liquid to within a few inches of the top. The top can, being inverted, floats on this liquid achieving a gas seal. The top can has a hinge device in the center, connecting it by a linkage to the aforementioned stop. The gas enters near the bottom of the bottom can and is piped upward to the top of said can. The gas goes through a similar pipe and exits on the opposite side to the engine. When turned on, the gas enters the space above the fluid, raises the top can and shuts off the incoming gas. As the gas flows into the engine, it exits the same space above the fluid, and the linkage opens the stop in the same manner as previously described. When the engine settles down to its working speed, the top can works in an up-down motion with the intake stroke opening and closing the stop. If the gas supply is shut off while the engine is running, the top can drops as the engine takes in fuel until it sets on the bottom and the engine stalls.

In the oil fields, the liquid in the gas-ometer was generally crude oil. Crude oil was readily available and trapped any rust that may have entered through the steel gas lines. About the only disadvantages to a wet gas-ometer would be the need to keep the bottom can filled to the proper level and to avoid any moisture entering the system.

Other than the top can (diaphragm), the only moving parts are the linkage and the stop. As the linkage moves in small increments under a light load, it wears very little. The stop, though, requires a little attention, in that the core must be kept clean and well greased. This core must be tightened enough to where it will not leak, yet still move freely. Gas-ometers were made in several sizes, corresponding to the size of the engine.

For safety reasons, a gas-ometer should be located a short distance from the engine, generally about 10 feet away, and stored in a small enclosure called a gas-ometer house, which resembles an outhouse. As you can imagine, after years of use and spilling a little crude oil once in a while, the gas-ometer and surrounding area became well soaked. For this reason, most gas-ometers found in the oil fields are in surprisingly good condition - on the outside. In reality, moisture will inevitably find its way into the gas-ometer and the thin sheet metal bottom will be found in bad shape.

Photo 1 shows a gas-ometer in its empty position. Note that the top can, or pot, is resting on the bottom and the stop is in the open position.

Photo 2 shows the gas-ometer in full position. The pot has floated up with the gas pressure until the linkage has closed the stop. In the running position, the pot will be somewhat lower, opening the stop just enough to allow a little gas through as the engine requires, thus being self-regulating. The small pipe coming out of the tee on the high-pressure side goes to the hot tube. This arrangement allows for a steady amount of gas to the tube and a controlled amount of gas to the throttle valve.

These gas-ometers are becoming harder and harder to find. They are primitive in today's world, but are simple in operation, efficient in use and with normal care will last a lifetime.

Contact engine enthusiast Harold Keller at: Box 46, Route 1, Glouster, Ohio 45732.

Contact the Oil Field Engine Society at:
1231 Banta's Creek Road,
Eaton, OH 45320-9701;