Thursday, August 3, 2017

REPLACING THE LP FLEX LINES IN AN AIRSTREAM INTERSTATE

This is a follow-on to this post in which I described a propane fill line failure in a friend's 2007 Airstream Interstate Class B RV.  As is often the case with RV repairs, I've gotten conflicting information from different sources, and after I publish this post, I'll go back and amend the other to reflect what I learned in the interim.

We decided to proceed with a DIY removal of those line segments of our propane distribution system that were not copper.  Our Interstate actually contains a mixture of copper (to refrigerator, hot water heater, and furnace - lines that penetrate into the interior of the living space are reportedly required to be made of copper), braided flex (fill and overfill, and to Onan generator), and solid flex (internal distribution segment) lines.  The braided flex lines were of three different diameters and were manufactured by Parker.  The solid line includes a tag indicating that it was manufactured by Marshall Gas Controls.

Note our DISCLAIMER for this kind of DIY work.  If you screw up working on your LP system, you could kill yourself.  Don't do any work if you don't have confidence in your abilities.

These were our steps.

First, I did a total burn-down of the LP tank so that it would be completely empty ahead of this job.  I ran the generator until it coughed out of operation from running out of gas.  Then after it quit, I cranked up the stove burners and watched the flames slowly shrink and sputter out.  Then I opened the residual lines to vent any remaining wisps of gas.  This step may not be strictly required on a rig such as ours, but I don't feel comfortable working with a tank full of flammable gas.

Second, I switched off the LP solenoid.

Third, I labeled the lines to be removed.

Fourth, I took a lot of photographs of the way that everything was connected (see above).  We could probably remember what went where, but why trust memory alone when the cell phone is right there in the pocket?

Fifth, it was then necessary to dismount of the lines.  My husband did this part, as brute strength helps in the process.  Plus he has far more general "working on cars" experience than I do, so he knows what things are supposed to feel like.  If anything abnormal manifested in this process, he'd be better able to detect it.

Line dismounting was not as easy as it could have been for two reasons.  Number one, there's the chronic issue of working in very tight spaces under the Interstate.
It is immensely helpful to do a four-wheel stack of the vehicle during this process, so that sufficient clearance is obtained for working. See this post for some ideas on constructing ramps, if you don't want to buy them.  
Number two, these lines were all in place for ten years and very well married to their fittings - getting a few of them free was no easy task.
It's not a simple matter of putting a wrench on it and taking it off.
This is best done as a 2-person job for this reason:
The second person can put an additional wrench on the line and prevent it from being torqued as the first person is applying major pressure to the nut in order to free the flex segment.
For some reason, the most challenging line was the one to the generator.  That took a good 20 minutes of patient work to free.

Sixth, we isolated those fresh, shiny threads from weather and road grime by cutting the fingers from nitrile gloves and using elastic bands to hold them on all exposed nipples.
At one point I bellowed from underneath the chassis (summoning my husband who was in the garage), "BUBBA, I NEED MORE CONDOMS!" when I ran out of finger segments.  Then I thought to myself, "Aw shoot, this is a family neighborhood... I shouldn't be screaming stuff like that."  :-)
Seventh, I freed the lines from their various chassis clamps.


Lines were thusly removed.
There she is... Miss America.  Sort of.  This photo looks a bit like a work of modern art. Interblog's "Ocotillo" or something. 
Eighth, I cataloged my removed lines.
I also cleaned and zip-tied them.
I was going to take them to a Parker authorized dealer to have them replicated, but I wanted to make sure I retained the essential information because I had no other go-bys.  If something happened to these lines, if they got misplaced or whatever, then I'd be S.O.L. and somehow would need to start from scratch.  My specs were as follows (outer diameters, or ODs, measured using an calipers):

  1. Fill - Parker brand, 64.75" long, 0.78" OD
  2. Overfill - Parker brand, 61.5" long, 0.53" OD
  3. Genset - Parker brand, 78.5" long, 0.65" OD
  4. Distribution - Marshall Gas Controls brand, 49" long, 0.66" OD, catalog # 42613-48 (stamped as "Flex Tech 3/8 RHA-6 Gas Hose Max WP 350 PSI)

That last one appeared to be an off-the-shelf product, but I couldn't find that exact number on the internet and I didn't know if the "close" numbers represented the same spec.  For non-consumer items, sometimes internet listings can be vague and incomplete.

Ninth, I took those neatly-bundled lines over to the hose-maker.

Tenth, a few days later, I retrieved the new lines from said hose-maker (and paid him, of course).
This shows one end of the fill line, old (left) and new (right).  The hose-maker used his discretion on which fittings were fit for re-use, and which needed to be new ones.  Some of the older fittings were actually compression fittings, not crimped, and were re-usable.  But in those cases where there was an issue, they were not.  An example is the line to the generator.  We partially rounded off the nut due to the difficulty in freeing the line from the generator.  For that reason, a new fitting was used. 
Eleventh, I re-installed and re-clamped all the hoses.

Twelfth, I had my husband check that all lines were secure.

Thirteenth, I checked the lines again, as a few weeks had passed between the re-installation and the impending propane fill.

Fourteenth, as we were en route to the propane filling station, I recited the following:
^^ The patron saint of female camper van DIYers. 
Fifteenth, we filled the tank with propane, keeping the solenoid valve closed even after the fill was completed.
For the first time ever, a female service person filled our tank, rather than a male.  I think it was Holy Mary in disguise.  
For my future reference, this is what our nominal six gallon tank takes when bone empty.  
Sixteenth, we came home, opened up the solenoid, gave her the smell test, and tried the appliances.
We were greeted with vigorous performance.  
 Seventeenth, with it having passed the smell test, I proceeded to crawl under the chassis for a more detailed leak assessment.
For that, I needed this.  Soapy water to wet all the connections and watch for bubbles. 
Crawling under the chassis in the absence of ramps was pure Suckville, especially with the exhaust train being blistering hot as we'd just driven back from the propane station.
Nnnnope.  Nada.  No bubbles anywhere. 
I stayed under there for about 10 minutes, waiting to catch of whiff of the slightest leak of propane or maybe see a bubble form, but nothing happened.

This wasn't exactly a relaxing project, and I'm tremendously relieved to see it completed.
Well, I was kind of on a meme theme, so I figured I'd stick with it.  Whew, indeed. 

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