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 Post subject: Propane plumbing
PostPosted: Tue Oct 18, 2016 10:26 pm 

Joined: Wed Jan 15, 2014 9:14 am
Posts: 174
For those of you that use lpg to heat passenger cars, what materials and methods are preferred for plumbing from the tank to the appliance. I have seen rubber hose, copper and black pipe, plus combos of all three. Any info is appreciated.


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 Post subject: Re: Propane plumbing
PostPosted: Tue Oct 18, 2016 11:11 pm 

Joined: Fri Aug 20, 2010 8:25 pm
Posts: 245
I use LPG to heat my residence and water, dry my clothes and to power a whole house backup generator.

I prefer stainless steel pipe, copper tubing and LPG rated flexible hoses.

Stainless is more expensive upfront but worth it long term maintenance wise.

I have several buried (underground) copper tubes in my delivery system, the latest code calls for plastic coated tube (yellow plastic overcoat).

Flexible hoses (aka "whips") come in two basic kinds; braided stainless steel and "rubber".

These should always be installed between a rigid plumbing system (pipes and tubes) and any gas consuming appliance to absorb vibrations from the appliance and not transmit the vibrations to the rigid plumbing system where they might eventually cause leaks.

These hoses are also very useful when connecting to tanks that need to be changed out. The hose makes the exact positioning of the valve on the tank less critical. Using a copper tube to connect to a non-permanent tank is just asking for trouble, eventually the tube will get bent/kinked and will fail.

The end of a flexible copper tube should be securely mounted before it mates with a flexible hose. The idea is to have a rigid well supported piping/tubing system with flexible whips to isolate the vibrating appliances/tanks from the "plumbing"

Black iron pipe is acceptable, but the cost difference between SS and iron is very small (unless you are running 100's of feet of pipe).

Always use valves/fittings/sealants rated for LPG. Some parts are rated for NG but not for LPG. Most "regular" water valves (including most 1/4 turn ball valves) are not rated for LPG.

There is a braided flexible stainless steel tubing system approved for installation in residences, not sure that it is appropriate for Railroad cars. They claim is it safer in earthquake prone areas. It might make sense for a complete retrofit;

http://www.csstfacts.org/

And always install a "stub end" (short piece of pipe extending down from a "tee") just before the gas supply enters any appliance. This is necessary for NG systems to allow small chips of sulfide scale forming in the pipes from breaking loose and entering the appliance. It is now also required for LPG systems under the newest residential codes.

If you are doing any substantial amount of new or refurbished piping invest in a manometer (pressure gauge) to help in leak testing. Install your pipe, pressurize it with clean air, shut off the input valve and watch the pressure gauge for any drop in pressure. A good tight piping system should hold pressure for many hours and even days.

Cheers, Kevin.


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 Post subject: Re: Propane plumbing
PostPosted: Wed Oct 19, 2016 3:25 pm 

Joined: Fri Oct 01, 2004 1:33 pm
Posts: 284
Location: Oroville, CA
I was taught to never use plain copper tubing for Propane. Apparently it reacts with it.

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 Post subject: Re: Propane plumbing
PostPosted: Wed Oct 19, 2016 6:44 pm 

Joined: Fri Mar 26, 2010 11:43 am
Posts: 419
Location: Floyd, AR
I would suggest using at a minimum DOT (vehicle) rated components. If you are going on the mainline and/or Amtrak, you should research the requirements they have.

I have used these guys in the past, they had all the DOT LP knick-knacks you could ever want.
http://www.gasequipment.com/home.html

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Any information or opinions I express are my own, and are not the views of the CBRHS or anyone else, unless explicitly stated otherwise.


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 Post subject: Re: Propane plumbing
PostPosted: Thu Oct 20, 2016 2:57 am 

Joined: Sat Aug 28, 2004 3:25 am
Posts: 1025
I concur with the "Don't use plain copper tubing"--not sure about LP gas, but whoever installed the water heater in my old house (built CA 1948) used copper tubing to connect the heater input to the natural gas supply pipe. Apparently something in the gas reacted with the tubing. Everything was fine until I replaced the water heater with a new one from Sears. Flakes from the tubing (probably dislodged during the installation of the new heater) got into the valve mechanism, and the third time a Sears tech came out to fix it, he brought a flexible brass connection tube which cured the trouble. Fortunately this was all under warranty--I double checked the instructions and there wasn't a thing about the connection tube.

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 Post subject: Re: Propane plumbing
PostPosted: Thu Oct 20, 2016 4:50 pm 

Joined: Fri Aug 20, 2010 8:25 pm
Posts: 245
"I was taught to never use plain copper tubing for Propane. Apparently it reacts with it."

Plain copper tubing is approved for propane. It requires a plastic exterior overcoat if it is buried. It is not approved for installation inside the framing of buildings. I have a hundred feet or so of buried 1/2 copper tubing between a large exterior tank and my residence installed by my propane supplier.

NG and copper is a different story. NG contains contaminants that deposit on the interior of the pipe/tube. This happens for all types of pipe but copper is the worst.

If the pipe/tube is rattled these break loose and can flow into an appliance (water heater, etc.) These small flakes will plug the tiny orifices in the valves/burners and make them inoperative.

This is why proper gas pipe installations have a small piece of pipe hanging down vertically off a tee just at the inlet to the appliance. This pipe is capped at the bottom and acts as a "sediment trap" for any solid particles to fall down into without entering the appliance. The tee is pointed vertically and the inflowing gas makes the bend to the appliance while the sediments keep going straight and down into the trap.

Kevin.


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 Post subject: Re: Propane plumbing
PostPosted: Thu Oct 20, 2016 7:46 pm 
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Joined: Sun Jun 27, 2010 12:24 am
Posts: 255
Location: H2O-town, CT
Plain copper isn't to be used with natural gas and is against building code. Either way it doesn't apply here anyway.


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 Post subject: Re: Propane plumbing
PostPosted: Thu Oct 20, 2016 8:19 pm 

Joined: Mon Aug 23, 2004 12:59 pm
Posts: 522
For those interested in the mechanical and chemical aspects of metallic gas appliance connectors, this Consumer products Safety Commission document from 1982 has quite a discussion (around page 27, I think) of the issues.

https://www.cpsc.gov/PageFiles/80568/cr1n.pdf


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 Post subject: Re: Propane plumbing
PostPosted: Thu Oct 20, 2016 9:46 pm 

Joined: Mon Jul 13, 2015 9:57 pm
Posts: 31
Location: Honesdale, PA
I dont know what other railroads require.
We Require schedule 80 steel piping and fittings, secured in similar manner as air lines to frame of car, all piping must be marked conspicuously. Piping may not be routed above trucks or below bottom of center frame rails. Tank must be secured to car and conspicuously marked. We permit Two flexible connections, one at appliance down stream from valve and one at tank. No flexible metalic material permited as it is prone to vibration induced fatigue failure. All installations are subject to the satisfaction of safety inspection by CMO.


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 Post subject: Re: Propane plumbing
PostPosted: Thu Oct 27, 2016 10:29 pm 

Joined: Wed Jan 15, 2014 9:14 am
Posts: 174
Sorry for the late response. I appreciate feedback. I am assuming that there is no standard for railroads on this. I have checked the cfr with no results, other than bulk lpg transport. We have a NW caboose that has a propane tank from when it was in service. Copper was used except for a flexible hose at the appliance. Copper is also standard on RVs. Of our 5 in service cars, 1 is copper, 2 are black pipe and approved rubber hose and 1 is almost all hose. I find it strange that there is no written rules on this.

Is there many organizations that use propane for heat? What other forms of heat are common? Obviously electric is popular for equipment with HEP or large gensets. What about the "little guys".


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 Post subject: Re: Propane plumbing
PostPosted: Sat Oct 29, 2016 8:22 pm 

Joined: Fri Aug 20, 2010 8:25 pm
Posts: 245
"We Require schedule 80 steel piping and fittings", whoa, that's a bit of overkill.

Normal pressure at an LPG appliance is 10-11 inches of water column, (WC). That's about 0.5 psi (yes 1/2 psi). Schedule 80 seems likes a 25 pound sledge hammer applied to a 6 penny nail.

Pressure right at a tank can get up to 200 psi (depending on the temperature of the tank) but normal practice is to install a regulator near the tank to drop things down to about 10-15 psi. This is the 'High pressure regulator", then piping delivers the gas to a "Low pressure regulator" near the appliance. If the tank and appliance are close together a "Two stage regulator" is applied.

The high regulator near the tank is a safety feature, if a leak in the line downstream from the tank/regulator occurs the regulator limits the volume of released gas.

If you have an LPG piping system designed that requires schedule 80 piping you have done something wrong. Schedule 80 might be nice for longevity, but it is not necessary because of the internal pressure from the LPG.

Of course since all of the air brake piping is schedule 80 using common parts to install LPG piping as schedule 80 makes some sense with regards to stocking common parts, tools. etc. But there is no technical engineering reason that requires schedule 80 pipe for LPG.

Also, Propane is heavier than Air, Natural Gas is not. A propane tank should not be installed in an enclosure that is closed at the bottom. Putting them in a closet inside a car that has no openings at the bottom for leaking LP gas to "sink" out of is not recommended. In residential practice regulators need to be installed above ground level by a minimum of 18" and away from a "source of ignition" by 4 feet. The regulator can exhaust LPG under certain conditions, this exhausted gas needs to be far enough away from an ignition source to dissipate before combustion.

Cheers, Kevin.


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 Post subject: Re: Propane plumbing
PostPosted: Sun Oct 30, 2016 10:46 am 

Joined: Thu Aug 26, 2004 2:50 pm
Posts: 2091
Location: Northern Illinois
NYCRRson wrote:

If you have an LPG piping system designed that requires schedule 80 piping you have done something wrong. Schedule 80 might be nice for longevity, but it is not necessary because of the internal pressure from the LPG.


Seems to me the Sch. 80 requirement is an excellent idea to prevent breakage during minor collision / hard coupling events. In railroad service, systems have to survive more than just system pressure.

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 Post subject: Re: Propane plumbing
PostPosted: Tue Nov 01, 2016 12:10 pm 

Joined: Wed Jan 15, 2014 9:14 am
Posts: 174
I could see using sch. 80 pipe for consistency of material, and being able to cut down on anchor points on long runs. Fatigue failures would be rare as well. Is it necessary? Maybe not. I am shocked that there is no industry standard for these types of installs. If there is, it has been elusive to me, and the people I have talked to in the lpg industry.


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 Post subject: Re: Propane plumbing
PostPosted: Tue Nov 01, 2016 12:59 pm 

Joined: Thu Aug 26, 2004 2:50 pm
Posts: 2091
Location: Northern Illinois
Who even makes propane equipment for heating RR cars these days? I know some caboose stoves used to be propane (and the infamous Icinderlet toilet), but that equipment is all ancient history. Likewise the Waukesha A/C systems. If there is no need for a standard, why have one?

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 Post subject: Re: Propane plumbing
PostPosted: Tue Nov 01, 2016 1:04 pm 

Joined: Thu Jan 12, 2006 10:10 pm
Posts: 670
Location: Iron City
Perhaps the place to look is the NFPA code.

Dave

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