Propane plumbing - adding cat heater

Almot wrote:
Thanks, guys. Will try and avoid straight pipe fittings. More questions:

1) Straight FIP: click on the video at bottom of the page for Brasscraft excess flow valves - they connect male flare of the excess flow valve to straight FIP of the shut-off valve. (Must be straight FIP because shut-off valves only have FIP or male flare).

2)

Chris Bryant wrote:
Compression connections are not used on gas- only flair or inverted flair.

What would be the right fitting to put on 3/8 OD copper pipe then? I mean, on the "copper" end.

3) Low pressure or high pressure. It will be from tall 70 lbs cylinder. Being a seasonal camp - possibly will install stationary tank in future. Either scenario will include a propane regulator that originally came with trailer, and I "think" this is called low-pressure. Or not?

4) Shut-off valve in easily accessible location - I'm hearing this all the time, but "easily accessible" is difficult in my case. The whole 2ft run from copper feeder pipe to the heater will be under the dinette bench, exiting out of the bench few inches from the wall-mounted heater. Shut-off valve under the bench? no, thanks. It will be easier to go outside and shut off the valve on the tank. Then I can unscrew the line from the heater and put a plug on it. Meanwhile, excess flow valve between the copper feeder line and heater will shut it off if there is a rupture downstream.

5) Mex: what problems did you have with copper tubing? Also, any links to inline propane filters?

To the OP..

I can't imagine what problems Mex has had with copper tubing. Trailer manufacturers have been using it for years. If the connections are properly done and tested for leaks, and the tubing is secured so that it does not vibrate and rub against anything, it should provide a lifetime of service.
Copper tubing is easily mated with black pipe if the proper fittings are used. Black pipe and copper gas fittings all use NPT threads and any fitting will mate with a black pipe coupler, Tee, Ell, or Street Ell of it's same thread size. The threads need to be sealed with pipe dope or yellow thread tape made for gas. Flared fittings are easy if you have done them before, if not it can be an exercise in frustration. It's not rocket science, but it does take a certain amount of knowledge.
After reading this thread a couple of times, my comments are meant as constructive and not condescending so please tale them as such.. Given your lack of knowledge on this subject and with no experience working with LP systems, I would enlist the help of someone who is knowledgeable in working with propane systems. It's not like miswiring something where you reset a breaker and get another chance to do it right. While propane is for the most part a perfectly safe cooking and heating fuel, a mistake while handling it or putting together a delivery system can be catastrophic, and you may not get a redo.