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hooking up propane correctly the first time

PostPosted: Fri Jan 13, 2017 10:21 am
by gene so
I am building a 9 foot camping trailer for hauling behind my 4 x 4. It will have dual batteries and propane tanks for long term off road usage. The wiring has been run and is kept in a sub floor. I need to hookup properly the propane lines to connect for the cabin heater, the cooktop and refrigerator. I have waited now 5 months for professionals to come and help me with this, nobody has appeared and I realize I must learn how to do this properly, if for no reason other then my own safety.
I was told to mount the propane line inside steel tubing for safety, which I can do. I am told of steel lines and copper which need to be flared, and the tool to do this correctly is costly. I am told about forged steel nuts that won't crack under strain. I also had a reference for flexible lines, but its frustrating when nobody around here seems to have any expertise in this area and the propane dealers are obviously too busy.
I need to run the line, then finish the plywood body, before attaching the vented box up front that will hold the propane tanks, batteries etc.

Thank you for your attention in this matter.

Gene So

Re: hooking up propane correctly the first time

PostPosted: Fri Jan 13, 2017 10:56 am
by Dale M.
Typically you would use 1/4 or 3/8 steel {in a pinch 1/2 inch} (black iron pipe preferred) under trailer body and "T" or 90° fitting with short riser through floor to a shut off valve (or not) then a copper line with flare fittings from steel pipe to appliance... Plumbing below trailer is run exposed because propane as a gas is heavier than air and needs a route to drift away from any possible leak, by putting piping inside a tube you are maybe creating route to direct leaking gas vapor to a place where you do not want it to go IE: cabin...

Use good Teflon tape for all NPT joints (except for flairs) or if that does not work for you get propane gas approved pipe dope (I'm old school and use pipe dope) .... Mount piping with clamps and some sort of rubber "bushing" to act as insulator and flex for pipe to chassis...

When all plumbing is complete put pressure gauge on piping and put it up to 10 psi and let sit for 24-48 hours and if pressure does not drop, you probably do not have any leaks and are good, apply fuel and test appliances...

Flaring tools are not "that" expensive... Ask neighbor who does their own auto or home repairs if they have one you can borrow... Check local hardware stores or auto parts... IF you ave to buy, a decent one is typically in $20-$25 range... ... aring+tool


Re: hooking up propane correctly the first time

PostPosted: Fri Jan 13, 2017 6:37 pm
by MtnDon
I prefer Rectorseal T Plus2 pipe dope with teflon for pipe joints. It is messier than teflon tape but I can not ever remember having a leak when I used that.

I like this Rigid flare tool. It costs more than some Chinese imports but it is very reliable. I have found some of the cheaper ones are harder to use, especially with larger size tubing. (I have bent the arm on a cheap one doing 3/8" copper.) You may be able to rent a good one at some Home Depots.

You can get the iron pipe cut to length and threaded at HD and Lowes stores. If having lengths cut be sure to account for the pipe ends being threaded into the fittings... pipe gets shorter as it is threaded in. Also, you want to use the black iron pipe, not galvanized when doing propane. I would not run copper inside steel unless the ends of the steel were left open so any leaks can dissipate. Running black iron underneath is excellent although you will find many commercially made RV's with nothing but copper underneath.

Don't worry about forged steel nuts, the brass ones are all that is needed. In 40 years of assorted RV's I have never had a fitting fail.

Re: hooking up propane correctly the first time

PostPosted: Fri Jan 13, 2017 10:58 pm
by Shadow Catcher
An alternate choice is copper, acceptable to RVIA standards. I re-did ours which originally had 1/2" black iron with copper and flare fittings and I leak test each summer.

Re: hooking up propane correctly the first time

PostPosted: Sat Jan 14, 2017 5:22 pm
by elcam84
Steel pipe (called black iron pipe) and it's cast fittings are good in houses however I would never ever use them on a vehicle. The reason is that the fittings are quite brittle and very susceptible to damage from vibration.
Copper also has its issues as well with vibration and work hardening. However I'll use copper over steel pipe in a camper.

Like mentioned it's best to have the lines exposed to eliminate any possible issue with vapor pooling in enclosed spaces. IE run it under the floor but protected from road debris.

Also a short story.. I have seen several boat trailers that have had the brake lines run inside the frame tubing. The idea was to protect them from debris. What really happened was since they were inside a tube they would sit in water and rust out. Some within a year or two because one they were in a steel tube and small vibrations wore the coating off the tube then the water was there up against it.
A friend had a 25th anniversary Mastercraft and he was heading home one day and when coming to a red light the trailer brakes failed because the brake fluid all went out a rust hole. Luckily there were no cars crossing at the intersection... I re piped it for him and it never had another issue.

Running lines in another tube is always possible but needs to be done with precautions and forethought to the application.

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