Copper Pipe Size?

[jr3149]

Hi,
I am planning on replacing the copper LP lines on my Trade Wind and I am wondering about appropriate size of the piping i should use. I have read from other forums that I should use type K copper.
My questions are:
What size ID / OD copper should i use from the regulators to the point of use?
Should I use different sizes from the main line to the T/Valves and from the Valves to the inside of trailer (where they attach to the appliance?)
and Lastly - is is possible to use a flexible hose type of attachment for the point of interconnection to the appliance? (i was thinking that this would prevent kinks in the future.

Can anyone shed some light on this subject?

[InsideOut]

You may want to consider using PEX & Sharkbite fittings...it's a lot easier to work with in a retrofit situation ~ we did in our '56 and are real happy with the results.

Shari

[clancy_boy]

I think the OP is talking LP (PROPANE) lines.

Check with trailer repair locations, LP systems present a whole lot of issues with replacment for the DIY people. Flex lines usually have a label that states on them not to be used in a high vibration location - once bent they don't want to be moved - that really is not the situation in a RV. There are rules on making connections internal to the RV, and what types and locations of valves. In general there should not be any concealed connections in the walls or under the floor - just straight pipe.

[idroba]

If you have the original copper pipe LP gas system, just replace it, like for like. That way you will know it will work just fine.

On flexible lines to the final use point: I am not sure there is any advantage doing that, but do not use the corrugated metal ones that are used on home interior hookups, like to a range or water heater. They are not legal in RV's, and do not take the constant flexing that they would encounter in an RV. Possibly you could consider rubber lines for the final connection, but again, I am not sure there is any advantage over solid copper with flair fittings, as was done at the factory.

Other than physical damage and two cracked flair nut fittings, I have seen very few problems with the copper gas lines that were the original equipment on any of the 17 or so AS products I have had over the past 33 years.

[cliffcharb]

as stated by idroba, just replace with the same size. When we re-did our trailer i believe we used 1/2" for the main line and 1/4" going into the trailer. You can buy the copper tubing from HD or Lowes. The only flexible line I used was to hook to the regulator. There really is no need for flexible line in the trailer. Make sure you flare all of your fitting, dont use compression fittings.

[InsideOut]

Originally Posted by clancy_boy

I think the OP is talking LP (PROPANE) lines.

Oops, sorry!

Shari

[edglenn]

Good question. It comes up a LOT. I had the same question myself when I started. Check throught the archives for more info.
I'll recap what I think I know (others please chime in):
Propane is VERY explosive if it leaks, so don't cut corners. Don't risk it.
Eliminate all extra shut-offs, T's, and flexible connections inside the trailer.
All propane lines need to be routed outside (underneath) the trailer, and penetrate through the floor directly to the appliance.
The main line (vintage trailers, at least) are 5/8" or 1/2" from the LP tank regulator. The secondary lines branching out are 3/8".
Install the petcock shut-off's underneath, at the main line or where they penetrate the undercarriage.
Type "K" is thick walled copper pipe, listed for propane. Lowes and Home Depot usually don't carry it. They only carry "L" or "M" for water and refrigeration.
Use only flared fittings, so you'll need to purchase a flaring tool.
Too much argument about single-flared or double-flared due to code changes. Take it for what it's worth.
What I did (which may or may not be the "best" way) was redo all the propane lines that were crushed/damaged under the trailer, keeping the usable parts. I disconnected the branch lines, and installed new brass petcocks and double-end female swivle fittings at the existing "T". I routed new copper tubing to each appliance, and poked them up through the floor, using black rubber pipe at the penetration to protect the copper tubing. Inside I routed the copper tube directly to each appliance, and connected with a flared fitting. NO FLEX HOSE!
Underneath I also used a clear, braided hose, with wire ties, split along the length and wrapped along the copper tube, for extra protection. Also use the rubber grommeted clamps, to prevent chafing the tubes.

Here's a couple pics of what I did:

[ATTACH]



[/ATTACH]

[jr3149]

THanks to all for the great responses (especially Edglenn)... I now have the information needed to attach the propane and try to hookup the furnace before the snow flys (so i may be able to peck away it it thoughout the winter. I was thinking of using split loom but i like the plastic hose idea better for protection.
Thanks again to all.
JR

[MarkR]

Does it bother anyone else that you are to buy 5/8" Flare Fittings for 1/2" Tube/Pipe? . . . I know that the actual 1/2" Tube's O.D. is 5/8", but they sell it as "half inch" . . . why not either call the "half inch": 5/8"
OR
Call the 5/8's Fitting "half inch"?

I just bought all new copper tubing.
And fittings to match what I thought the tubing required (1/2" Fittings for 1/2" tubing), and sure enough Murphy seems to have infiltrated my "experience" again.

I'm wondering if the "three eighths" tubing (1/2" o.d. and 1/2" Fittings) would be big enough for the main line(?). All 4 appliances require or come with the 3/8" Fittings, or "quarter inch" tubing (3/8" o.d.) . . . which would be "2 steps" down from the main line if I was to go w/ "half inch" tubing (5/8" o.d.) . . . ?

And on a related note, does anyone know how to read/use this chart?

Propane Gas - Pipe Sizing

[idroba]

Originally Posted by MarkR

And on a related note, does anyone know how to read/use this chart?

Propane Gas - Pipe Sizing

On the tabular charts, the pipe size (nominal) is listed, then the run in feet, and then the capacity in MBH (thousands of BTUh).

So lets say the furnace is a 30,000 BTUh one, the water heater is 10,000 BTUh, the range is 20,000 BTUh, and the refrigerator is 1500 BTU. That total is 61,500 BTUh or on the charts would be 61.5 MBH

To size the pipe for the maximum flow from the regulator, you would look for the length you are running, and 61.5 for the MBH, then locate the size. For branches, say the furnace at 30 MBH, you would look at the furnace run from the main pipe, and do the same.

[MarkR]

Idroba, Do you know what they mean by:
"fittings factor 1.5 - equivalent pipe length = pipe length + 50%"

My system is long gone so I'm starting from scratch, but I'm pretty sure the original line from the regulator was not "half inch" (5/8" o.d.) . . . but maybe it was (?)

[55AS]

I think it means you add 50% to your actual length to account for fittings.

[Jammer]

Type K Refrigeration tubing is available at some (not all) home centers and hardware stores, or can be ordered from Grainger and similar places. Trailers are small, so cost per foot isn't the big deal it is if you're putting in a barn heater or something. Fitting prices will drive you budget.

The cheaper flexible copper "utility tubing" has a thinner wall and isn't safe for propane.

You're supposed to use forged nuts, which I do. The reason is that in a wet environment that is subject to freezing water could get between the nut and the tubing and freeze, and the regular nuts can crack if that happens. With forged nuts the nut is stronger than the ice. Not a hypothetical problem under a trailer, so use the right materials.

You will need a flaring tool. I find that an inexpensive one works well. Whether inexpensive or not they require practice, and the screws should be oiled often. It is typically necessary to roll the cut end of the tubing out a little with a screwdriver or something (I use the handle of the flare tool) if a tubing cutter was used, because the lip the tubing cutter makes will end up making a fold in the flare, leading to leaks.

I use a commercial leak detection compound. Kids' bubble stuff works ok too. Regular dish soap isn't quite foamy enough unless you add glycerin, which is too complicated for me.

Larger tubing is harder to work with and won't bend as tight so you want to use the most appropriate size. Typically, for any RV, 3/8" O.D. is used for runs to individual appliances and 1/2" O.D. is used for the main line. 1/4" O.D. is theoretically large enough for a gas light or fridge and may make sense in some situations, but is rarely used by manufacturers.

Any time I'm installing a large amount of tubing I pressure test it to 30 PSI with air. All the appliance connections, and the regulator, have to be disconnected from the piping and the connection plugged to do this. It's a hassle but if there are leaks you will find them. If I'm just adding a fitting or two I just use a bubble test because I figure that the chances of introducing a leak when disconnecting all the appliances are greater than the chances of missing something with the bubble test.

Approaches differ but I find it works best to lightly oil the threads of the flare fitting, and the outside of the pipe where the nut contacts it, before assembly.

Propane lines require care and skill to install safely. I would suggest finding a local mentor since it's your first time.

[Jammer]

Originally Posted by MarkR

Idroba, Do you know what they mean by:
"fittings factor 1.5 - equivalent pipe length = pipe length + 50%"

It's a shortcut way of allowing for all fittings. Just add 50% to the pipe length and that compensates for all the Ts and elbows. More detailed tables will sometimes give an equivalent length for each fitting.

My system is long gone so I'm starting from scratch, but I'm pretty sure the original line from the regulator was not "half inch" (5/8" o.d.) . . . but maybe it was (?)

I've never seen one that was on a trailer. I have a (stick) house that has propane appliances, and it uses that size for the 20' run from the regulator to the first appliance.

[MarkR]

Thanks for the help.

Got another "stupid question". I've assumed that when I turn vertical and penetrate the belly pan w/ the "final run" of tubing to each appliance, that I would use a 90 degree elbow fitting and then go all the way to the appliance connection point. Now that I'm about ready to install, I'm thinking, "if the rule is no fittings in enclosed places - like the belly pan - then how do you justify the end of the elbow with a flare nut sticking in the belly pan . . .

So I started thinking, I better check in w/ the experts (again, I'm starting from scratch so I don't have anything to look at).

Thanks, MarkR

[idroba]

You don't use the elbow, but make a smooth bend in the pipe with one of the spring like tubing benders that you can get at a hardware store. Thats the way the original pipes were done, a bend in the pipe, not an elbow.

[Jammer]

For the 3/8" tubing you can also use an automotive tubing bender, which will give you a sharper bend than the springs will. An inexpensive one is sufficient.