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Old 02-06-2005, 05:12 PM   #1
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Join Date: Nov 2004
Location: Tampa FL
Posts: 52
How to run Propane Lines?

What are the standards?

What materials; steel, copper, brass?

Flared fittings all the way or mix and match with pipe tread?

I've got to run propane from my two tanks on the outside to a stove top, refridgerator, and an outdoor grill.[/img]
Nicholas Frey
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University of South Florida

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Old 03-27-2005, 08:56 AM   #2
Join Date: Mar 2005
Location: Plymouth MA
Posts: 195
Propane lines

There are two main systems for propane lines, copper and black iron pipe. There are stainless piping systems that are available, but these MUST be installed by a licensed plumber, and at any rate I do NOT know if they are listed for RV installations.

Both copper and black iron have their advantages and disadvantages.

Copper is amazingly flexible, relatively cheap, easy to cut and splice, add tees or cap off dead ends.

Black iron is heavier, rigid, requires more expensive tools to cut/thread/install, and is sometimes difficult to get cut to an exact length for a small space. Plus, I need expensive unions to break long runs into managable lengths.
Having said that, I like black iron for exposed runs under vehicles, as the strength and rigidity can't be excelled. It can easily span the distance from frame rib-to-rib without sagging. I JUST make sure it's properly attached, with insulated hangers (to prevent chafing/rattling).

Inside a vehicle, I use copper for it's adaptability. Simple flare fittings are an inexpensive way of making connections, and the only tools I need are a GOOD tubing cutter/reamer (with a SHARP wheel, natch!), and a flaring tool kit.

NOTE: I do NOT use compression fittings for copper! I use ONLY flare fittings, properly installed! Compression fittings can NOT guarantee a tight leakproof seal to my way of thinking.
Copper's flexibility serves me well for snaking it into cabinets and around corners, HOWEVER it has to be supported over any distance or it will sag, and may vibrate loose or fatigue fracture. I HIGHLY recommend using rubber/plastic grommets at every hole it passes through, even through wood, and ESPECIALLY through metal holes like in floors or bulkheads.

Another consideration is SIZING. The CAPACITY of the tube/pipe determines the size of the appliance(s) downstream, and vice-versa.
I know what I want to install, FIRST. THEN I run a larger main supply tube down the vehicle length, branching off (WITH A GAS-RATED SHUTOFF!) at each location.

Tube/pipe sizes can be determined by your local LP supplier. I ask them about what size tube/pipe I should run for each appliance, and for all the appliances as a whole.

Do-it-yourself books carry a lot of info on making up copper tube connections, and some iron pipe info.

NOTE: When making black iron pipe connections, I use the proper GAS-RATED thread sealant ONLY on the outside of the pipe threads, NOT on the inside of the pipe fitting threads. The pipe dope will ooze into the pipe if I coat the inside threads, and will eventually break off and make it's way into the appliance I'm using, making for a VERY frustrating disassembly and cleaning job.

NOTE: when making a long run, I add a small vertical 'drop' for debris and moisture to fall into NUST before it gets to the appliance. You'll see what I mean when you look at the supply line for your home water heater or furnace; there is a tee and a capped section that is there JUST to collect crap and prevent system clogging.

NOTE: I DO NOT use galvanised pipe for a gas system, it is not rated for gas retention. If I need rust resistance, I paint the exposed piping after thoroughly cleaning it! I use a good degreaser, followed by a good primer, and two or more THIN coats of paint.
POR15 is an excellent base coat for the pipes.
Cold galvy spray may also work in some situations.

NOTE: I ALWAYS check my connections for leaks, using compressed air instead of gas. Home centers and hardware/plumbing supply places sell small bottles of joint testing fluid, I smear it on joints and pressurize my system to test.

IIRC, most LP systems are less than ten (10) PSI downstream of the regulator(s), check with your LP guy for more specific info for your setup.
If I need to pressurize the system with air, I just put an adapter on the pipe that allows hooking a bicycle pump to the system.
Instead, I cap off the fitting (appliance) ends before testing the system.
THEN I install the appliances after testing the main pipes, and check those new connections with the leak finder fluid while under gas pressure.

NOTE: when I do an appliance installation, I always tape a spare tube/pipe cap next to EACH appliance end connction. That way if I need to pull an appliance in the field, I can shut off AND cap the connection for safety's sake....the part I need is already there ready for installation.
Cheap insurance.

NOTE: I recommend you have a Licensed LP installer inspect your system before gassing it up for the first time. A little insurance in the form of an expert's attention can save your RV and your lives.
The tool storage is nice, but where do I put the bed?
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Old 03-27-2005, 09:01 AM   #3
Join Date: Mar 2005
Location: Plymouth MA
Posts: 195
Oh BTW, I believe there are quick-disconnect fittings available for exterior appliance (like grills) use, you'll have to haunt plumbing supply houses (and maybe some RV shops, I don't know) to find them.

Good luck
The tool storage is nice, but where do I put the bed?
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Old 03-30-2005, 03:57 PM   #4
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Location: MA
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What about plastic? When they replaced the natural gas main in front of our house a few years ago I was surprised that the 12" main and the house runners were all plastic.

Are there plastic systems for propane?
My 1989 Thomas Saf-T-Liner
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Old 12-06-2005, 08:28 AM   #5
Join Date: Mar 2005
Location: Plymouth MA
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Sorry to get back so late

No, there are NO plastic gas lines for residential/do-it-yourselfer use. Tools and materials are far too specialized for Average Joe to use.
The tool storage is nice, but where do I put the bed?
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Old 12-06-2005, 10:59 AM   #6
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Good stuff Ryan; thank you.

Bus conversion/info here
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Old 12-11-2005, 10:17 AM   #7
Join Date: Mar 2005
Location: Plymouth MA
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Just found out there are quick-disconnect fittings to use for external camp stoves, grills etc.

Try the local BBQ grill sales places and suppliers, they should have 'em.
The tool storage is nice, but where do I put the bed?
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Old 12-11-2005, 06:44 PM   #8
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Nice work Ryan - thank you for taking the time to do this!
Lurking in perpetuity project starting Fall '06.
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Old 01-06-2006, 09:55 AM   #9
Join Date: Mar 2005
Location: Plymouth MA
Posts: 195
Gas shutoffs

I've found Lowe's has gas valves, down to 3/8th inch pipe size.
You might find smaller (1/4, 1/8th inch) in a GOOD hardware store, and there's always the plumbing supply places........

Ace Hardware in Hudson MA supplied me with some 1/4 inch gas shutoffs that I used for my chuck wagon.

Gas shutoffs will be either pipe threaded or set up for flare fittings.
The tool storage is nice, but where do I put the bed?
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Old 03-18-2006, 09:53 AM   #10
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Location: Whidbey Island, Washington (USA)
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There is another alternative as well. I'm in the marine industry and am involved in outfitting a lot of custom cruising boats. Due to the harsh marine environment and the constant movement of boats the most common propane lines aboard are hoses which are specifically made for the application with swaged ends. Your choice of which system to use for installation of a propane system will be influenced quite a lot by cost of materials and the layout of your bus and how many propane appliances you're supplying.

In my bus I supply three appliances; the stove/oven, the water heater and a Dickenson Marine stainless vented (direct-air) wall mounted fireplace (heater). Like BruinGilda and many others I am using portable propane bottles mounted in a compartment under the bus to facilitate refilling without having to move the bus to the propane station. I have a manifold just downline of the regulator under the bus to which each of the individual hoses connects. Then there is a single continuous run of hose from the manifold to each appliance. Where the hose enters the bus through the floor there is a purpose built bulkhead fitting (the hose slides through and then a plastic nut is tightened which compresses multiple fingers against a rubber grommet to make a tight seal) to protect the hose and in this case keep critters, spray, fumes, etc outside. The hose then connects directly to the appliance.

What I like about this system is that I have only one connection inside the bus for each appliance (and specifically right at the appliance) and it's a factory-made swaged fitting of high quality. The connections for the multiple runs are all made under the bus near the propane compartment at the manifold; they should be vapor-tight and sealed well but if they do leak it won't be inside the bus. Shut off valves can be installed at the manifold to facilitate shutting off an individual appliance.

Several approaches to installing propane systems are viable; this isn't meant to suggest that this method is "the best". I only offer it as an alternative since many folks are not aware it exits. Outlets like West Marine and others carry the hoses. The system is used almost exclusively in yachts today and is designed to withstand the rigors of world cruising sailboats operating in tropical (read harsh) climates.
Les Lampman
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