Accumulator tanks, gas-o-meter plans

[Jim Gorter]

Hello to all, I am trying to increase my understanding of oilfield engines and would like to find out more on accumulator tanks and gas-o-meters. Are accumulator tanks necessary and how should they be sized. I have heard of gas-o-meters being used in the old days. How are they made and how do they function. Also, would like to find a site which explains the workings and parts of a two cycle Reid engine. Thanks for the help, Jim.

[W.P.Klein]

Try oldengine.org for a manual. The gasometer served as an accumulator as well as a regulator. An accumulator is usually necessary if running the engine & hot tube from the same gas supply. It serves to keep the engine from gulping all the fuel & shutting off the hot tube. It is a good idea anytime but many engines run for show purposes without an accumulator if fed from a different tank or if the engine is spark fired. Bill Klein

[Andrew Mackey]

As for Reid engine operations - The Reid oilfeild engine has 2 pistons, rods and crank pins. One cylender casting, with 2 bores, and a common chamber at the head, with valves between the cylenders, and on the inlet side of the outboard cylender. The outboard cylender, be it on the left or right side (were built both ways), is the charging cylender, and the centered cylender is the power cylender. The power piston has its crank throw 90 degrees advanced from the charging piston throw. I will walk you thru a stroke-cycle in the Read-LeClerk 2 cycle engine
First, with the charging cylender at top center, the engine is turned in a CCW direction (top of flywheels toward rear of engine). This draws the charging piston away from the top of the cylender- thus drawing in air and fuel, past a poppet inlet valve. At the same time, the power piston is advancing, and passing top center. As the charging cylender piston passes the bottom of its stroke, and the piston begins to compress the fuel-air mixture in the cylender, there is no pressure on the power piston side of the head space at the top of the cylender, as the now receding power piston has uncovered the exhaust port at the bottom of the power cylender. The compressing air-fuel mixture is then blown from the charging cylender, past a poppet valve, and into the power cylender. As the crankshaft rotates, the power piston covers the exhaust port, and then also begins to compress the fuel air mixture. When the pressures on both sides of the poppet valve in the head space equalize, the valve closes, and pressure continues to build on the power piston side, as the piston advances. In the mean time, as the charging cylender is now empty, the piston is again at top center, the intake cycle begins again. This time as the power piston nears top center, the fuel-air charge is ignited - either by hot tube or spark plug, depending on age and or refit of the engine. The ignited charge drives the power piston down the bore, turning the crank, and producing power. About 3/4 of the way down the bore, the exhaust port is uncovered, allowing the burnt gasses to escape to the atmosphere, thus dumping the pressure in the power cylender. As the power piston nears bottom center, pressure from the charging cylender pushes air-fuel gasses past the head space poppet valve again, into the power cylender, further clearing out the burnt gasses, until the exhaust port is covered by the now advancing power piston. The cycle now repeats. Later Reid engines had a relief valve fitted to the charging cylender. This valve prevented damage to the charging cylender and the connecting rod, if the poppet valve failed to close off the power cylender, or if there was an engine backfire.

Later Reid engines had a governor. Earlier engines used a 'lean run' system of speed regulation. Lean run systems ran as follows: When the engine was started, the amount of fuel was regulated to limit the engine speed. At low speeds, the engine ran rich, providing power and acceleration. As the engine speeds up, the limited amount of fuel leans out the mixture. Eventually, the air-fuel mixture becomes so lean, it won't ignite, and the engine would slow down. This reduction in engine speed would richen the mixture again, and the engine would again fire and accelerate. Setting engine speed was a delicate balancing act, as load, weather, air density, and gas pressures were all variable. If the engine was mounted near a well head, and there was a gas leak in the area - running the engine was downright hazzardous! Many an engine was lost when unregulated gas got into the intake of a hot tube engine! The Reids were no exception, and their unique dual piston and rod setup made for a spectacular display of destruction when one blew a rod! The later governed engines did away with most of the runaway situations.
Here are some other facts: A hot tube ignition works in the following manner: A hot tube is a closed ended pipe mounted near the top of the cylender or head on an internal combustion engine. The hot tube is heated to a dull red heat, at a given location on the tube. The closer the heated spot is to the cylender, the more advanced the timing will be. Timming cannot be retarded any more than 5 to 10 degrees before top center, as I will explain later. As the fuel - air mixture in the combustion chamber is compressed, it is pushed into the hot tube assembly. When the fuel-air mixture hits the red hot spot, a miniature explosion takes place, and the flame front then travels back into the combustion chamber, igniting the rest of the charge there, thus providing ignition. As only so much pressure can be generated by compression, the fuel-air mixture can only advance so far into the hot tube. If the heated section is too far up the tube, the mixture cannot reach it, and will not ignite. Also, runninng a hot tube engine retarded fully for long periods will cause the tube to be weakened by the constant over pressures and heat, brought on by lean explosions in the tube. Eventually the tube will fail, sometimes in a spectacular fashion - like the end of the tube blowing clear out of the chimney at terrific velocity. (I saw the end of one go about 100 feet in the air, when a weakened tube shattered.) It is always recommended that to view a hot tube in operation, and to check heat location on the tube, that a mirror be used to observe the flame and tube. If the tube should fail, or the gas should flare while you are looking at the mirror, no harm done except for a broken mirror, and perhaps a burned finger or 2. If your face is there - Hot tube engines always have the fuel-air mixture in the cylender. Also, Hot tube engines always have to have heat on the tube at all times. If the tube heat fails, the engine shuts down, usually in less than a minute.

Hot bulb engines are not to be confused with Hot Tube engines.

Hot Bulb engines have an entirely different operation. A hot bulb or oil engine as they are sometimes called, has a bulbous section built onto the head. This bulb is heated to near red heat, and at the proper time, fuel is introduced into the bulb, where it ignites. The amount of power, and speed are governed by the amount of fuel introduced. In this manner, they behave much like a deisel engine, with one major difference - A true deisel needs between 18 and 22 to one compression ratio to operate effeciently, and fuel is ignited by compression pressures. At 4.5 to 6 to one, the hot bulb engines are not even close to deisel operation pressures, the heat from the bulb provides the ignition source. Once a hot bulb engine is started though - it will continue to run as long as it has fuel. In this respect, one has to be very careful starting a hot bulb engine. If there is not enough heat in the bulb to start the engine, fuel must be turned off immediatly, and the engine purged before attempting to start again. If the engine is not purged of fuel, when the engine does start, it will burn all the fuel in the bulb - leading to uncontrolled acceleration, and possible engine damage - even to catastrophic failure!
Andrew

[Jim Gorter]

Thanks guys for the great explanations, The cycle description of the Reid was exactly what I was looking for. Is there a book on Reids that show the poppet valves and linkage? Thanks again for a quick education, Jim