LPG/Propane filling

[InterBlog]

Originally Posted by rmkrum

Front row seats to a rapidly expanding propane fireball are not my idea of a “great experience “. I need to check and replace a set of old, stiff propane hoses on my 10 year old AS. Thanks for the reminder...

Well, if you are LUCKY you'd have a front row seat. In the case of the Interstate, the propane tank is under-slung, mounted directly beneath the bed in our model, about 2.5 feet below the head of my side of the bed. So the failure scenario might be more like humans on the barbie than humans in a front row seat.

[rmkrum]

Either way, close proximity to such an event is not going to be fun... Prepare for lots of stinging! (Line from Over the Hedge movie)

[InterBlog]

Originally Posted by InterBlog

...
The manufacturer of the hoses installed by Airstream stated to me by phone that those hoses have an expected serviceable lifespan of 5 years (and NO, you won't find that tidbit in your Airstream owner's manual). .....

I'm adding substantiation to my comment above for ease of reference, and because Airstream seems to be reading forum threads more closely these days (New Year's resolution maybe?) and perhaps could take a tip from this for future improvement, because it's an important issue.

Our 2007 Interstate came supplied with two references to the propane system as follows:

(1) An Airstream-produced owners manual which describes the LP plumbing on pages 62 and 63.

The only replacement recommendation this source provides relates to the regulator, as follows: "Replace any regulator that has had water in the spring case, or shows evidence of external corrosion, or corrosion inside the spring case. Closely examine regulators directly connected to the container valve by means of a solid POL adapter (horizontal mounting) for signs of corrosion. (An Airstream Service Center is recommended for this service.)"

(2) A set of generic RV safety booklets produced by the organization called RFSEV. You can see the latest edition of this series here.

The "Propane" booklet does not contain any references to propane lines that I have found, EXCEPT within the context of potential damage in a roadway accident such as tire blow-out or due to vibration. There's nothing in this material that eludes to the possibility of the lines needing to be replaced when they become too old to remain in service.

In fact, there's not much context on lines at all. On page 6 of this booklet, it says "Propane coming out of these containers must pass through industry approved valves and regulators." Well, the LINES have to meet industry standards as well, eh? But no mention of that.

FWIW.

[duckdave]

Wow. Lots of good information here! Looks like I might need to build me some drive up ramps like Interblog describes here http://interstateblog.blogspot.com/2...airstream.html.

Speaking of checking everything twice and near tragedy with propane...we were once towing down route 66, probably in Oklahoma—one of those bumpity-bumpity-bumpity sections of concrete two lane—when one of our 40# propane tanks became dislodged and started dragging down the highway. We had just had both tanks filled the day before. I could mention the name of the RV place that did not install the tanks back on the tongue properly, but thankfully they are out of business now. It seemed like one of those "should I stay, or should I run" situations. Very briefly, in my mind I thought "best to be ahead of the blast, than in the middle..." Before I had a chance to react, there was much hissing, the highway filled up with a fog of propane, and the tank passed us at a high rate of speed. Everyone on the road came to a stop.

Thankfully, the tank was aluminum, no sparks—that's probably what saved us.

Anyone need a scratched up 40# aluminum tank with only a small hole in it?

[duckdave]

Your state might be like mine in that "doing" propane breaks down into a bunch of different areas. Here in NM, for instance, there are nine different licenses for propane; I hold only one, namely, the one that permits me to fill cylinders. No transport. No repairs. No installations. No recerts. No nothing else.

So, then, it could be that your propane place simply isn't permitted to work on those cylinders. (In addition, I don't know about your state, but mine does not recognize RV propane systems as anything particularly different from other propane systems, at least in terms of licensing.)

Get on the phone and do some calling around.

I suspect licensing is more lax here in Arkansas than elsewhere. I think they just didn't want to mess with it.

I've had a hard time finding competent places to get RV work done. I thought I had one with the RV place that filled that tank that fell off the trailer. But, that visit I had 4 things done, and none of them were done properly. When we finally got a dealership in Little Rock, at first they didn't know anything about Airstreams (trailers), but eventually they got up to speed and got good at repairs. Then they dropped the franchise. Another RV dealer picked it up a couple of years ago, but I'm still hearing mixed reports.

[InterBlog]

For the nerds among us, this post might qualify as your trippy skull experience for today. Trippy with a dash of small world phenomenon.

The atoms came smashing together in my brain like this. All this talk about flammable gas leaks and possible catastrophic fireballs due to a rubber-like component that might fail on the Airstream Interstate, and at the same time, we just moved through late January, which is a big deal in our neck of the woods, as this is the time of year when we remember the Challenger and Columbia crews (my husband LB_3 works in Mission Control at Johnson Space Center).

For those of you who are newer to the forum, over the years, there have been a number of comparisons of the Interstate to the space shuttle. Someone even hatched a thread called “Where to park the space shuttle”.

At the same time as we are discussing the potential for flammable gas leaks on this thread, I’m working on “Feynman-izing” a description of our lithium battery system for another thread. Dr. Richard Feynman developed a learning technique that requires breaking down complex information into simple components and developing ways to explain those components to an uninitiated person. “If you can’t explain it to a child, then you don’t understand it well enough yourself.” <-- If you’ve ever heard this sentiment expressed, you have the late Dr. Feynman to thank for it.

And then I connected the dots. Feynman was the guy who pretty much singlehandedly made the breakthrough on the cause of the space shuttle Challenger explosion. And although the contractor Morton Thiokol is widely believed to be responsible for the failed O-rings, Thiokol was actually the booster manufacturer. Thiokol got the O-ring materials from what was then called Parker Seal Group. Which today is a division of Parker Hannifin. Which is the very same company that manufactured the flammable gas hoses for the Interstate (at least that is true for the older models).

Let that odd nexus sink in. As it was with the winged space shuttle, so it is with the wheeled space shuttle, at least on one particular level.

It’s almost like there’s a type of techno-karma echoed in all of this. Feynman documented the profound disconnect between NASA’s engineering pool (analogous to RV DIYers) and its executives (analogous to those who manufacture and sell RVs). The executives oversee the production of materials that document and disclose risks as they see them (e.g., emphasis on propane REGULATORS), but these materials are arguably not in accordance with what is actually being perceived by the engineering boots on the ground (e.g., emphasis on propane LINES). Embedded in our situation is a bit of the same style of cultural disconnect that the Challenger team faced.

Moral of this imaginative tale: Be like Feynman. You never know where the resulting thought experiments will take you.

From Wiki:

[Feynman] warned in his appendix to the [Rogers] commission's report (which was included only after he threatened not to sign the report), "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled."

[rmkrum]

Feynman is still revered, legendary, and mourned at CalTech. He was amazing, and a hell of a nice guy as well.

Eldest son graduated from CalTech in ‘94

[Boxster1971]

Originally Posted by InterBlog

... And then I connected the dots. Feynman was the guy who pretty much singlehandedly made the breakthrough on the cause of the space shuttle Challenger explosion. And although the contractor Morton Thiokol is widely believed to be responsible for the failed O-rings, Thiokol was actually the booster manufacturer. Thiokol got the O-ring materials from what was then called Parker Seal Group. Which today is a division of Parker Hannifin. Which is the very same company that manufactured the flammable gas hoses for the Interstate (at least that is true for the older models). ...

... Feynman documented the profound disconnect between NASA’s engineering pool (analogous to RV DIYers) and its executives (analogous to those who manufacture and sell RVs). The executives oversee the production of materials that document and disclose risks as they see them (e.g., emphasis on propane REGULATORS), but these materials are arguably not in accordance with what is actually being perceived by the engineering boots on the ground (e.g., emphasis on propane LINES). Embedded in our situation is a bit of the same style of cultural disconnect that the Challenger team faced.

I think there needs to be some clarification to the dots you are connecting. These are the facts as I know them:
1. The O-rings on Challenger were not inherently defective. The O-rings failed because the launch was made in unusually cold conditions. Conditions that the O-ring was not designed to fly under.

2. The Rogers Commission found NASA's organizational culture and decision-making processes were key contributing factors to the accident, with NASA violating its own safety rules.

3. NASA managers disregarded warnings from engineers about dangers of launching in low temperatures of that morning, and failed to adequately report these technical concerns to their superiors.

How do I see this relating to our Interstate (and other RV) LP lines:
1. The LP flex lines are not inherently defective. They can fail because they are used longer than there were designed to be in service.

2. The executives and managers at Airstream and other RV manufactures are not telling their customers to replace these hoses when they age out beyond their design limits.

3. We don't know what the Airstream engineers are telling their managers and executives.

I don't equate the RV DIYers to the NASA engineers. I think RV DIYers, like yourself InterBlog, are more analogous to Dr. Richard Feynman, trying to get to the true facts and limitations of our RVs. RV manufactures and their engineers are more analogous to NASA executives and engineers. The RV owners are analogous to the poor crew of the Space Shuttle Challenger, especially Payload Specialist and Teacher Christa McAuliffe. We RV owners can face a potential disaster because RV manufactures are not telling us about the design life span of LP hoses.

The problems seems to go beyond the RV manufacturs. For example here are two articles I found quickly that talk about tank, regulator and detector life, but never mention replacing hoses.
http://www.motleyrvrepair.com/propan...ty_and_use.htm

http://www.trailerlife.com/tech/diy/the-abcs-of-lpg/

This issue needs more research. Are some RV manufactures using better hoses? I doubt it.

[Boxster1971]

More research for sure... I took the term "RV" out of my search and just used "service life LP hoses" and found a lot of good information. This hose age issue crosses many applications.

Here are just a few examples with some good information:
http://www.ybw.com/forums/showthread...nd-replacement

http://www.gasequipment.com/catalogs...F/18-Hoses.pdf

https://www.scubaboard.com/community...rences.548448/

http://www.safehose.com/hfa_1.html

[Boxster1971]

OK - I've spent a few hours trying to find an authoritative source that pins down the service life of LP gas hoses. The only references I could find to the five year life are from UK sources like this:
https://www.calor.co.uk/media/wysiwy...ing-250913.pdf

Parker, who make a lot of these hoses, gives no specific length of time. All their sources I could find have this statement regarding service life:

"4.5 Replacement Intervals: Hose assemblies and elastomeric seals

used on Hose Fittings and adapters will eventually age, harden, wear and

deteriorate under thermal cycling and compression set. Hose Assemblies

and elastomeric seals should be inspected and replaced at specific

replacement intervals, based on previous service life, government or

industry recommendations, or when failures could result in unacceptable

downtime, damage, or injury risk."

I did find one Parker sources that gives some dates. Same one I may have posted earlier about a "Guide for Hose Failure Analysis". But from my read it is about hydraulic hoses.

http://www.safehose.com/hfa_1.html

Also found one from a boat insuance company that sasy life is 5-10 years.

https://www.boatus.com/magazine/2014...sted-hoses.asp

That's enough from me.

[InterBlog]

I was making an analogy, not a literal comparison.

But yes, neither the O-rings nor the hoses are "defective". But as Parker argued during the Challenger investigation, just because something is manufactured perfectly to any given spec does not mean it can be used in every conceivable scenario (I'm oversimplifying for brevity).

As for the 5 year determination, looking back over my notes, that came from either one or two of the three Parker reps I interfaced with. I made my initial call to their corporate department on or about May 12, 2017. I had my buddy's hose on our garage bench at the time and I basically asked the rep, "This hose failed, and I don't know why, because I'm looking at it, and I don't see any damage, or wear, or visible evidence of break-down. I don't know what the remedy should be, if I'm without knowledge of the failure cause." My initial phone notes, which I also reproduced on my blog, read as follows:

"...I spoke with two customer service reps who told me the following:

"The marking "1006" indicates the hose was manufactured in October 2006, which is consistent with the age of our rigs.

"MH8742" indicates a technical standard. In this case, and as the CPSC recall notice confirms, this type of hose was typically used in consumer-grade gas BBQs.

The rep stated that a leak emanating from a 10-year-old segment of this hose is not an unexpected event. A hose that old is near the end of its useful life; they don't last forever. If the hose had been years younger and developed a leak, they (Parker) might be interested in retrieving it to study what happened. But not a hose this old."

I remember that conversation well. The second corporate rep's responses were formal in terms of syntax but her tone of voice betrayed amusement. She was amused that someone would try to leave that kind of hose in service for a full decade.

I then proceeded to the local authorized sales rep who actually uttered a few choice obscenities when confronted with the facts. He was adamant about the five year lifespan.

Now, is it written down like five years, or some other years? I didn't look further. There's a guy about a mile from me who, by multiple references, is very good at his job and who is authorized by Parker to fabricate Parker hose segments with the correct fittings for specific applications. I took him at his word.

Realizing the wider rig ownership consequences that these hoses represent, before proceeding with that job, I had asked him to please recommend another brand or composition of hose that would potentially last longer than 10 years. He said, "No. It can't be done because this is the spec that was determined for this application. If there's someone else out there installing another grade of hose, then you have no idea how that other product is going to stand up over time, and that fabricator has obviously no grasp of his own liability for installing a non-spec hose."

FWIW.

[Boxster1971]

InterBlog - thanks for the extra info. Sounds like 5 years is our safe service life. Mine are now at 5 years and 3 months in service. Time to plan for replacing the hoses. Replacing the main fill line will be the biggest hassle as I assume the tank needs to be emptied first. I think I’ll check with local dealer about getting the job done. Should be interesting to hear their reaction when I tell them that the hoses should be replaced every 5 years. If it’s too expensive I may try to do it myself.

[InterBlog]

Now, this next part is where I didn't take as many notes as I should have, so take this with a grain of salt because it comes from my memory instead of my pen (I hate it when I do that - I need to write everything down in real time).

Because so few people seem to know about this issue, such a service request is uncommon and might be met with a quizzical response by your service rep. (S)he may look at the hoses, which will LOOK perfectly fine, and wonder why you want this done, and wonder why or how such a nice looking hose would not be considered safe to leave in service.

The answer might have to do with a safety mechanism that characterizes the hose. IRRC, there is some kind of "micro-perforations" or "built-in weakness" engineered into the hose. This measure is designed to prevent the thing from exploding if someone accidentally puts it under too much pressure. Instead of failing catastrophically in such a scenario and possibly causing a greater injury in the process, it's supposed to fail in a controlled manner.

Which is all well and fine until those areas of intentionally-engineered weakness get too old. And then they become REALLY weak to the point where they become leaks instead of potential safety valves.

Or so the theory goes. I wish I could substantiate who told me that, but that's what I'm remembering as a possible culprit in this situation. Someone please correct me if my memory is in error.

So that is what you might consider telling a skeptical service rep, if you encounter questions.

[Jbray333]

Under the FWIW category, after having the fill hose rupture in 2014 on our 2007 AI, I just had the remaining braided gas lines replaced by a local propane dealer. They manufactured and installed them for about $300. Headed to Alaska this spring and attempting to forestall their failure at that most inconvenient time.

[InterBlog]

The informal poll continues. We're up to three T1N Interstate owners with propane lines that leaked.

We paid something like $350 for the new hoses - similar price. Except I did my own installation labor which, in part, involved disconnecting part of the water plumbing because Airstream had nested a propane hose on top of it (typical Class B tight working conditions). So it did take some time, but nothing too extreme.

[Jbray333]

Originally Posted by InterBlog

The informal poll continues. We're up to three T1N Interstate owners with propane lines that leaked.

We paid something like $350 for the new hoses - similar price. Except I did my own installation labor which, in part, involved disconnecting part of the water plumbing because Airstream had nested a propane hose on top of it (typical Class B tight working conditions). So it did take some time, but nothing too extreme.

After following your incredibly helpful and detailed repair/upgrade procedures, I would trust your work over any other's, including mine!

[Sebtown]

I was fortunate when I replaced my propane hoses. It was a straight forward job and only took a couple of hours. I had the replacement hoses fabricated at my local farm equipment dealer. I only paid $156. for the pair!

[InterBlog]

Seb, it sounds like you may have replaced just your fill and overfill. I replaced four hose segments - there's a routing line under the chassis, and also the supply line to the Onan generator is a Parker line as well. Those lines which penetrate the chassis to internal components are all copper per code, I believe, so they don't require the same attention (fridge if 3-way, hot water heater, and furnace all have copper supply lines).

[Sebtown]

IB, you're correct. I guess I'm climbing back under when we return from this latest trip, thanks for the tip.