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mello mike · 01-29-2006, 08:01 PM

My wife and I recently went on a trip in our 1972 Sovereign. Near the end of the trip, I turned a corner and suddenly heard loud, metallic scraping sounds. The first thing that came to mind was that my WD hitch had come loose. I immediately pulled off the road and inspected my silver baby. What I saw left me totally speechless. Both propane tanks were dragging on the ground with the LP lines going to them damaged with gaping holes. The tension rod which kept the tanks and LP regulator secure to the A frame had snapped in two, leaving both tanks totally unsupported.

I was immediately struck by how fortunate we were. If the LP tanks had been left open the damaged LP lines coupled with sparks generated by the tanks dragging on the road would have resulted in an explosion and fire. This could have possibly taken the life of my wife and I. The incident still gives me the willies. I shudder to think what would have happened. I thank the Lord that I decided to turn the tanks off before we left to go home.

Anyhow, I thought I'd share this incident with fellow Airstreamers in the hope that folks would think twice before travelling with their LP Gas system charged. I know I'm a firm believer now. Don't travel with your LP system charged!!!!!

TwinkytheKid · 01-29-2006, 08:07 PM

You are very lucky the tanks were not punctured, and that the propane lines held.
Not saying I think you should have your propane on, but if you had aluminum tanks there would be no sparks if this happened.

NorCal Bambi · 01-29-2006, 08:22 PM

I'm rebuilding a 1963 Bambi. I will be adding a new rod to the propane tank mounting system. Thanks.

dwightdi · 01-29-2006, 08:22 PM

Some Airstream tie down rods were just cross pinned at the bottom. Sometimes the pins would break. I replaced mine with a threaded rod with two nuts at the bottom.

Some of the cast aluminum cross tees for the top of the tanks have been known to break. The casting have low ductility becaused they chose the wrong alumimun alloy when they made them. I think it was a high silicon alloy which is high strength but low ductility. I have a broken one of those too. You can not do anything about that but you should not overtighten the hold down wing nut.

A cross tee which is not tight enough may allow the bottles to wiggle and rotate to the point it will come to the opening in the handle and fall off the front of the trailer. I had it happen to me. I solved that one with a securing pin assembly which I made. Also works for steel tees.

**Stefrobrts** · 01-29-2006, 08:31 PM

Holy Moly! What a horrible near accident! I need to refill my tanks before the next outing, I think I will give the hold down system a good inspection. Thanks for the scary tip!

joecolao · 01-29-2006, 08:51 PM

Did that on the Cross Bronx Expressway in my 1977 31". The pin in the bottom sheared off. One tank was dragging under my trailer. Having a cover on the tank would have prevented this. I also recommend to those of you that do not have a cover, it is useful to install a strap around both tanks. WBCCI 30916

3Ms75Argosy · 01-29-2006, 10:01 PM

I had replaced my rod with a threaded rod also, but still am not satisfied with the hold they have on the tanks. I do have a plastic cover that holds them on, but I really don't like the cover. Can you show me a close up of those hold downs you made, or could I pay you to make some?
Thanks!
Marc

dwightdi · 01-30-2006, 06:57 AM

Here is a closer picture of the clips used with steel cross tee hold down on my 63 with steel tanks. The application is slightly different but the principle is the same. I used to use a plastic coated steel cable used to secure bikes with a lock. It also help prevent someone stealing the aluminum tanks. The safety guys at the International did not like tanks locked to trailer. They said," in case of fire they would come over and remove bottles before they exploded". I would like to see someone that brave (or stupid) trying to get propane tanks off a burning trailer.

JStanley · 01-30-2006, 07:16 AM

This Forum is great & I learn a lot here. I also use a plastic coated bicycle cable to lock & secure my tanks. I was thinking anti-theft, and not the possibility of falling off. I always turn them off when traveling, now I’ll update my checklists to ensure they are very secure. ‘Remove Tanks In Case of Fire’ is another issue. So I’ll get a bigger fire extinguisher to keep in the tow vehicle.

mello mike · 01-30-2006, 06:44 PM

Leaving your LP Gas system charged is obviously one. The other is the failure of the tension rod. Mine looked identical to DWIGHTDI's first post above except mine wasn't threaded the entire length. My rod simply snapped in two where the pin goes through.

The moral of the story is that frequent inspection of your entire LP tank and tie down system is a must. I love some the precautions some posted here to keep their tanks secure. You can never be too careful.

bill benton · 01-30-2006, 06:45 PM

Oh wow. When we travel with our propane turned off, you think all is well. I would have never thought the hold down rod was such a weak spot. Thank God those tanks didn't explode.I'm going to check ours first thing in the morning.

wahoonc · 01-30-2006, 07:09 PM

If the tank valves had been open the OPD mechanism would have kicked in and shut the flow off, it is part of what they are designed to do....that is if you have the properly upgraded valves. I am still seeing RV's with the old style valves. I agree there are better hold down methods for the tanks. You also have to take into consideration the age of the hold down mechanism, I am sure they have traveled many thousands of miles and been subjected to various types of abuse. Replacement of a 30+ year old hold down mechansim is probably cheap insurance.

Aaron

tin sista · 02-01-2006, 06:02 AM

Whew what an experience! Thanks for sharing it, I'm adding inspecting the propane tanks (making sure they aren't charged and looking securely fastened) to the departure checklist.

4slice · 02-05-2006, 01:19 AM

Hi all,

When I bought my '77 31', the p.o. told me about making sure the tanks were secured properly and to inspect the rod and hold-down, etc. as he had seen tanks come off a trailer before. I figured that must have been a freak occurrence and gave it no more thought.

The next morning, as I was driving the ten hours home over the Rockies with my new pride and joy, I was well behind an old SOB when I suddenly saw something white bouncing under the trailer (at 70 mph). I sped up to get closer and could see that it was a propane tank bouncing between the pavement and the bottom of the trailer!! Then I backed WAY off. The hose held on for almost a mile or so, then the tank came free, went under the axle (causing the SOB to lurch and bounce--the right wheel nearly left the ground), and finally hit the ditch. I couldn't believe that the driver didn't seem to notice. The highway was four lanes, and I had to really push it to get up beside him. He was a very senior citizen and didn't notice me honking and waving for about five more miles!!! Even then, he seemed to be suspicious of this idiot waving at him. Finally he pulled over and was a little huffy until he saw for himself what had happened.

Now I check and re-check the clamping set-up.

Gary H.
"4slice"
Prince George, BC

scf31 · 02-05-2006, 05:14 AM

These stories will make ya double check them, there are a lot of weight when they are full, a few jolts from winter roads or curbs

. thats a lot of pressure on that rod, if I remember correct, it is only a small cross pin, I will thke a better look when the snow and ice melts, these posts are good , it makes us all better informed as to what can happen .

bhayden · 06-13-2006, 04:17 PM

Quote:

Originally Posted by wahoonc

If the tank valves had been open the OPD mechanism would have kicked in and shut the flow off, it is part of what they are designed to do...Aaron

I know the OPD (Over Pressure Device) valves open to vent the tank when there's excessive pressure. Which means in a fire they become a giant Roman Candle rather than a bomb. How do they funtion if the system is inadvertantly openned? I think you can open a tank without the hose attached and it'll just release gas, no?

-Bernie

Excella CM · 06-13-2006, 04:53 PM

Another thing to check on tank mounts or any other system fastened with bolts & nuts, etc., is looseness. When there is any motion, the impact due to banging back and forth can easily exceed the strength of the the fasteners, shear pins, and fracture bolts at the threads. Frequent inspection will go a long way in insuring that the tanks are secure. A stout strap around both tanks through the tops might make it more difficult for either to just fall over toward the outside if the rod breaks.

uwe · 06-13-2006, 05:56 PM

Quote:

Originally Posted by bhayden

I know the OPD (Over Pressure Device) valves open to vent the tank when there's excessive pressure. Which means in a fire they become a giant Roman Candle rather than a bomb. How do they funtion if the system is inadvertantly openned? I think you can open a tank without the hose attached and it'll just release gas, no?

-Bernie

I learned that OPD actually means "overfill protection device". The device shuts off when the tanks are nearly full, preventing overpressure problems. Another device in the same valve shuts off the gas flow if there's suddenly a large volume of gas moving through, such as might happen when a hose ruptures.

bhayden · 06-14-2006, 10:30 AM

I stand corrected. The OPD accronym does stand for Overfill Protection Device. Basically that's all it does. All tanks have always had a pressure relief valve but if the liquid level in the tank is too high (overfill condition) it may not work. That's the reason propane cylinders should not be transported laying on their side. Here's a link on how the OPD valve works.

http://www.eddinger.info/opd.htm

As far as protection devices to prevent unwanted escape of gas the OPD and the older ACME valves (but not the POL valves?) appear to use the same technology. Here's another link that explains the differences and features but it doesn't go into just how thi s magic is accomplished.

http://www.co.scott.mn.us/xpedio/gro...zardframe.hcsp

I have a hose from pre OPD days that allowed me to use a 5# refillable tank with my portable grill designed for the disposable cyclinders. I was hoping to use this with the Airstream attaching it to the tank not supplying the trailer. It appears that the thread has changed to external and RH from the old internal LH thread. I haven't had the trailer tanks refilled yet but looking at them it appeared the hoses from the tank selector/regulator had the old style thread even though the tanks are fitted with OPD valves (triangular handwheel). The hoses and fittings also appear to be original circa 1978 and well worn. Now I'm wondering what sort of "chain reaction" I'm going to set in motion when I try to get the cyclinders refilled and replace the trailer fitting?

dwightdi · 06-14-2006, 11:51 AM

You can still use your original lines with the left hand thread but you need to use a wrench to tighted them properly. If you convert over to the new outside thread hoses you will be able to tighten them by hand. Seems like a good thing to do since the old rubber hoses age and get weaker. I have not heard how long they are good for but I would guess it is likely less than 10 years in the areas of the country with more ozone and sun exposure.