Bottled Fuel

[shiftpro]

That is what I was thinking also. Next question, going from propane to natural gas, which way did you go for the orifice (jet) change, larger or smaller?

35 yrs ago... there was a gas fitter involved and he just tossed the part at me.

 

[Frankenchevy]

That is what I was thinking also. Next question, going from propane to natural gas, which way did you go for the orifice (jet) change, larger or smaller?

I believe propane has less BTU. My guess would be bigger for propane to get the same energy. I’ve converted several appliances from Natural Gas to lpg, but can’t recall the differences in size of the orifice.

I think the gas ranges I’ve converted will typically have a 17,000btu burner on cng and typically state a lower rating once converted to lpg.

 

[gotyourgoat]

That is what I was thinking also. Next question, going from propane to natural gas, which way did you go for the orifice (jet) change, larger or smaller?

Basically the orifices for propane are smaller and the orifices for natural gas are larger. Natural gas is low pressure and propane is under high pressure so it needs a smaller orifice to push the same amount of fuel.
For instance if you had a natural gas setup and attached propane to it you would be flowing way too much volume through it, vs propane setup where you try to run natural gas through it and there isn't enough gas flowing though.

@shiftpro notes evaporators in the setup, those bring the pressure to a usable level in a vehicle instead of changing the size of the opening (orafice) after the regulator in a burner type setup.

 

[Frankenchevy]

Basically the orifices for propane are smaller and the orifices for natural gas are larger. Natural gas is low pressure and propane is under high pressure so it needs a smaller orifice to push the same amount of fuel.
For instance if you had a natural gas setup and attached propane to it you would be flowing way too much volume through it, vs propane setup where you try to run natural gas through it and there isn't enough gas flowing though.

@shiftpro notes evaporators in the setup, those bring the pressure to a usable level in a vehicle instead of changing the size of the opening (orafice) after the regulator in a burner type setup.

Is this the same for residential? I was under the impression that lpg and natural gas were both 7-9 psi after the regulator. The inspector only has me pump gas pipes up to 15psi for a test. He told me it’s double the pressure that the gas is at.

 

[Turbo4whl]

Basically the orifices for propane are smaller and the orifices for natural gas are larger. Natural gas is low pressure and propane is under high pressure so it needs a smaller orifice to push the same amount of fuel.
For instance if you had a natural gas setup and attached propane to it you would be flowing way too much volume through it, vs propane setup where you try to run natural gas through it and there isn't enough gas flowing though.

@shiftpro notes evaporators in the setup, those bring the pressure to a usable level in a vehicle instead of changing the size of the opening (orafice) after the regulator in a burner type setup.

Nature gas used in a vehicle is actually under very high pressure. To store the gas as a liquid the gas is compressed to 3600 PSI. CNG-compressed natural gas. Two water heated regulators (not water cooled) are used to drop the pressure. Propane requires much less pressure to store it as a liquid.

So a home heating unit or stove is receiving natural gas at a very low pressure compared to a vehicle.

 

[gotyourgoat]

Is this the same for residential? I was under the impression that lpg and natural gas were both 7-9 psi after the regulator. The inspector only has me pump gas pipes up to 15psi for a test. He told me it’s double the pressure that the gas is at.

That's a good question. I believe the the typical usable pressure is about 7.

Short answer is propane burns hotter than natural gas. Different apparatus are needed.

Everything from the main source should be for the fuel used. Propane should have a propane reg, tubing and orifice. Natural gas should have natural gas reg, hose, and orafice.

I know there are a lot of people who use whatever was setup there originally and just change the tips (orafices or burners) for household heating, grill, firepit and homebrewing. Now if that meets code...I do not know but it will work.

 

[gotyourgoat]

Nature gas used in a vehicle is actually under very high pressure. To store the gas as a liquid the gas is compressed to 3600 PSI. CNG-compressed natural gas. Two water heated regulators (not water cooled) are used to drop the pressure. Propane requires much less pressure to store it as a liquid.

So a home heating unit or stove is receiving natural gas at a very low pressure compared to a vehicle.

Hadn't thought about compressed natural gas. That's a different animal all together. Was simply comparing propane to regular natural gas.

Knew a guy who bought an old fleet vehicle and it may have been setup for this. Minus the tank. Most of the stuff was still in the vehicle and there was what I am guessing was the expansion tank for the liquid natural gas.

 

[Turbo4whl]

Hadn't thought about compressed natural gas. That's a different animal all together. Was simply comparing propane to regular natural gas.

Knew a guy who bought an old fleet vehicle and it may have been setup for this. Minus the tank. Most of the stuff was still in the vehicle and there was what I am guessing was the expansion tank for the liquid natural gas.

I am very familiar with CNG vehicles. I work on a fleet and we have had CNG duel fuel and dedicated units both. There is no expansion tanks, just the two regulators. The first regulator plumbed with 1/4" stainless steel lines receives the fuel at high pressure as a liquid. Dropped to around 75 PSI the fuel leaves that regulator as a gas in a 1/2" steel line.

The early Impco systems looked like the propane system in the pictures I re-posted. Later Angi systems were a series of solenoids each with different size orifices. The processor selects witch solenoids to open to match what is needed by the engine. They still had a mixer.

The newest systems are now port injected, pulse modulated. That leads to something some of you may not know. In the 1990's GM built dedicated CNG pickup trucks. The engines, 350 CI were made for the application. They were never sold, only leased to fleets. We had a few of these units, they ran well.

They did have one major issue. They were built without the tanks, then sent to a up-fitter to have the tanks installed. All the tanks were under the pickup body to leave the bed empty. Two of the tanks, long and smaller in diameter were mounted outside the frame in the wheel well area. Somehow the tanks could slide rearwards. They would stop at the rear spring shackle. The shackle moving with the leaf spring would wear on the tank.

So wearing the tank making it weak, when filling to 3000 PSI, (pressure max at that time) a tank blew up. (None of our units) After that all units were shopped for an inspection, adjusted or replaced as needed. Returned to service a second unit failed, (poor inspection??) GM reclaimed all units. They did not even drive them, sent in a carrier.

 

[gotyourgoat]

I am very familiar with CNG vehicles. I work on a fleet and we have had CNG duel fuel and dedicated units both. There is no expansion tanks, just the two regulators. The first regulator plumbed with 1/4" stainless steel lines receives the fuel at high pressure as a liquid. Dropped to around 75 PSI the fuel leaves that regulator as a gas in a 1/2" steel line.

The early Impco systems looked like the propane system in the pictures I re-posted. Later Angi systems were a series of solenoids each with different size orifices. The processor selects witch solenoids to open to match what is needed by the engine. They still had a mixer.

The newest systems are now port injected, pulse modulated. That leads to something some of you may not know. In the 1990's GM built dedicated CNG pickup trucks. The engines, 350 CI were made for the application. They were never sold, only leased to fleets. We had a few of these units, they ran well.

They did have one major issue. They were built without the tanks, then sent to a up-fitter to have the tanks installed. All the tanks were under the pickup body to leave the bed empty. Two of the tanks, long and smaller in diameter were mounted outside the frame in the wheel well area. Somehow the tanks could slide rearwards. They would stop at the rear spring shackle. The shackle moving with the leaf spring would wear on the tank.

So wearing the tank making it weak, when filling to 3000 PSI, (pressure max at that time) a tank blew up. (None of our units) After that all units were shopped for an inspection, adjusted or replaced as needed. Returned to service a second unit failed, (poor inspection??) GM reclaimed all units. They did not even drive them, sent in a carrier.

That's interesting. What would have been the purpose of the tank in the trunk? It was horizontal up towards the rear seat and about the shape/size of a 1/6th barrel keg or a corney keg (5gal or so) but without handles. There was a bunch of plumbing with all sorts of valves and fittings on it in there as well.

 

[Turbo4whl]

That's interesting. What would have been the purpose of the tank in the trunk? It was horizontal up towards the rear seat and about the shape/size of a 1/6th barrel keg or a corney keg (5gal or so) but without handles. There was a bunch of plumbing with all sorts of valves and fittings on it in there as well.

For a car, there are not many places to put a large tank except the trunk. Newer tanks are composite. Less weight than steel. Maybe about 1/2" thick aluminium then wrapped with fiberglass to give the strength to hold 3000 to 3600 PSI.

 

[gotyourgoat]

But what was the small tank left behind in the trunk for?

For a car, there are not many places to put a large tank except the trunk. Newer tanks are composite. Less weight than steel. Maybe about 1/2" thick aluminium then wrapped with fiberglass to give the strength to hold 3000 to 3600 PSI.

 

[Turbo4whl]

But what was the small tank left behind in the trunk for?

That tank was for fuel also. If you are talking about a vehicle that had CNG, then removed they may have missed that tank. If the unit was duel fuel it may of still had a gasoline tank.

Some propane tanks were made to fit in the spare tire holder. Propane tanks are much thinner metal. When filled nowhere near the pressure of CNG.

 

[gotyourgoat]

That tank was for fuel also. If you are talking about a vehicle that had CNG, then removed they may have missed that tank. If the unit was duel fuel it may of still had a gasoline tank.

Some propane tanks were made to fit in the spare tire holder. Propane tanks are much thinner metal. When filled nowhere near the pressure of CNG.

He only ever put gasoline in the car. Told me they took the tank for the pressurized gas out before he bought it.

 

[shiftpro]

For a car, there are not many places to put a large tank except the trunk. Newer tanks are composite. Less weight than steel. Maybe about 1/2" thick aluminium then wrapped with fiberglass to give the strength to hold 3000 to 3600 PSI.

It's nice to get schooled on CNG. I've often wondered about some the of differences with LPG. Thanks for joining the site.