Flex line for propane stove.

stand up or sit down...to sink or not to sink...want or got gas...post your Q&A here..........

Postby Larry C » Sun Jun 12, 2011 8:54 am

dh wrote:Larry, I am running galvanized pipe under the trailer and up into the gally, and up front I have a POL directly into a single stage regulator, then it turns down with a hydraulic rated street elbow into a 24'' hose that mates with the hard plumbing in front of the tongue box. Any flaws there? I was told by a local RV guy and an orange vested man that galvanized was ok, but have recently heard differently.


dh,
Many years ago I worked for a wholesale plumbing house. I handled miles of both black iron and Galv. pipe. I asked the same question of the plumber customers, and was told several different things:

1) It was the code

2) It was to differentiate water and gas lines so a gas line was not accidentally cut

3) the same reason Madjack mentioned about flaking.

4) The odorante used in natural ( maybe propane?) gas has sulfur in it and corrodes the zinc in the galvanizing.

I have no idea if all or any of the above are true.

For the hose connection: Personally I would use a hose with at least one swivel connection on one end. It makes life easier. The POL is one swivel, but one on the other end is nice.

Why the hydraulic street elbow? They have NPTF threads.

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Postby dh » Sun Jun 12, 2011 9:55 am

I went with the hydraulic fitting for two reasons. First, its what I had laying around the shop, second, I think it has a cleaner look than a black iron street elbow.
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Postby Larry C » Sun Jun 12, 2011 6:46 pm

dh wrote:I went with the hydraulic fitting for two reasons. First, its what I had laying around the shop, second, I think it has a cleaner look than a black iron street elbow.


The reason I asked is NPTF (dryseal) threads have a different thread form than NPT threads. Your regulator is probably made of aluminum with NPT threads, and the hydraulic ell is steel with NPTF (dryseal) threads.

The interference fit that is achieved with 2 mating NPTF (dryseal) threads will probably not happen as designed when the steel adapter is threaded into the aluminum regulator.

Pipe joint compound may take care of this mismatch, but frequent leak testing is appropriate here.

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Postby dh » Mon Jun 13, 2011 2:10 am

I'll have to look closer at it. Would brass be an acceptable substitute? Anything funky about flare fittings I should know? I ''barrowed'' a brass male flare fitting from work to go from the hose to the pipe. We use them for slide core water fittings on injection molds at my night job.
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Postby Larry C » Mon Jun 13, 2011 7:36 am

dh wrote:I'll have to look closer at it. Would brass be an acceptable substitute? Anything funky about flare fittings I should know? I ''barrowed'' a brass male flare fitting from work to go from the hose to the pipe. We use them for slide core water fittings on injection molds at my night job.


I have seen brass used for LPG connections more than anything else, but I am not sure flare fittings are currently being used for LPG connections on RV's. You should probably check into the current regs.
If flare connections are ok, make sure your hose has 45 degree flares. I would try to avoid universal flares (37/45 degree) Your brass adapter has a 45 degree flare.

You didn't mention the size yet. If it's 3/8" the 37 & 45 degree flares have different thread sizes, there is no universal flare so if the threads on the hose fits the brass adapter it will be a 45 degree flare. However, this is not the case if your using 1/4" or 1/2" pipe.

There is a possibly of an issue with dissimilar metals and electric circuits (brass, steel, aluminum). It might be a good idea to isolate everything from the trailer frame (electrical ground). Maybe someone else with more knowledge can chime in here.

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Postby dh » Mon Jun 13, 2011 10:58 am

I got the hose and regulator from the RV place and it came with NPT on one end and flare on the other, so I assume its usable in an RV. The flare is a 3/8'', so I should be ok there.


I don't rely on the chassis as a DC ground. Everything has its own ground wire run to it. However, the chassis is grounded on the DC side and will be on the AC side as well. Either way, the only place where brass meets steel is where the hoses connect, so electricity shouldn't flow there anyway.
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None!

Postby bearfromobx » Sun Sep 11, 2011 7:57 pm

bdosborn wrote:So what kind of hose do you use for gas appliances inside a trailer?

Bruce


I use the same soft copper refrigeration tubing run through protective chaseways that I use in any residence and flare fittings with a pressure test of the system before connecting any of the final appliances. I recheck the system for integrity at least once a year, ALWAYS turn the gas off at the tank when in transit or storage and ALWAYS use a battery powered combustable gas alarm. The biggest thing about combustable gas is not letting it build up in an enclosed space. Please don't forget that LP is heavier than air and pools in low spots, of which there are many inside a trailer.
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I have Jack...

Postby bearfromobx » Sun Sep 11, 2011 8:04 pm

... but only found residue of the zinc galvanize in the smallest pilot orfices and only with LP (I'm told the higher moisture content is to blame). It's funny though, living on the Outer Banks of NC, local code allows for galvanized pipe in gas supply systems!


madjack wrote:dh, black pipe was always the preferred product because(supposedly) zinc can flake off of galvanized and stop up the orifices of your appliances...some codes say yay and some say nay...in my experience, I have never come across an orifice stopped up from zinc flakes..............
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Re: Flex line for propane stove.

Postby Shadow Catcher » Wed Mar 28, 2012 7:54 pm

I used 3/8 copper from the POL fitting in the front to the flare fittings in the rear since it is traveling through aluminum a plastic sleeve and rubber grommets are used to prevent galvanic corrosion. The rubber hose attaching the two stage regulator to the POL fitting will be changed every couple of years.
The only other hose is the one from the Bullfinch gas point to the gas grill external to the trailer.
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Re: Flex line for propane stove.

Postby bdosborn » Thu Mar 29, 2012 8:00 am

Shadow Catcher wrote:I used 3/8 copper from the POL fitting in the front to the flare fittings in the rear


Me too, with the copper tubing tucked back behind the frame rails for protection from road debris.

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Re: Flex line for propane stove.

Postby fm-usa » Sat Mar 16, 2013 4:38 am

Fairly old thread indeedie but still relevant.
I stop in from time to time and see if anything new is happening.
We still don't have a TearDrop and may not have one in it's classic form for it's still on paper (well in Bitmap).
ANYWAYS, ...
I read this propane post and wondered a few things.
No propane hose...
.. has yet to be invented where it has an outer hose that is vented to the outside?
.. has a colored spiral stripe that will change colors when it's interior has sensed propane?
.. has an automatic shutoff internally and near it's source connection when propane is sensed?
I see 2 of these 3 ideas would be a little expensive add on to it's overall cost. And each idea has it's Pros & Cons as where and how it's used.
IMHO The most cost efficient and overall viable one would be the covering vented to the outside, then possibly have an alarm.
Next would be the Auto-Shutoff but that could be an accessory add-on right after the tanks valve so the overall cost is moot and it be reusable and transferable. Although MFG's want turnover moolah so that may not be in THERE interest.
.
I dunno, any other ideas?
:thinking:

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Is it possible, FULL RV in a 48 Sq.Ft. footprint & stay under 500Lbs wet?
SHE thinks teardrops are "cute" but I prefer a SKOSH more room & at 63+ the
body doesn't react/extract/move/mend/bend/lend or work like it use'ta.
NOW! That unwanted guests moving in, Mr. 'Arther I. Tus' & Ms. DVT (grrr)
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Re: Flex line for propane stove.

Postby Shadow Catcher » Sat Mar 16, 2013 7:02 am

The RVIA standards http://www.bustropolis.com/files/downlo ... mation.pdf were what decided me on using copper. The connections from the manifold under the trailer are all copper to the cook top, water heater and gas point. The only hose is the one from the two stage regulator to the copper pipe and is easily replaced.
One interesting difference is that in the UK and presumably EU they use/allow compression gas fitting where the RVIA standards call for flare.
Bob you salvaged single stage regulator may not provide sufficient volume to feed everything.

What Ever you use, Leak test. One of the first tasks for de winterizing the trailer will be to leak test the propane connections, all of them. Or thing could go BANG.
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