Propane line blowout?

sebaine · 07-07-2018, 05:55 PM

Has anyone else had their propane line/hose that goes from the tank to the regulator blow off?
I came home from work and as I was walking in I heard what sounded like high pressure water running through plumbing; as I walked closer to my TT it got louder and then I smelled propane.

I quickly removed the black shroud and saw that one of the lines had blown off and the tank was just discharging.
(NOTE TO SELF: Remember to ALWAYS close the tanks when not in use!)
I turned off the tanks and pushed the hose back on to the brass nipple. When I took the pics I tried to pull it back off to illustrate but it didn't easily come back off. I live in San Antonio, TX and the temps have been consistently around 100. I can only assume that may have played into the hose blowing off.
Any thoughts on the cause and suggestions for correction?
Thanks!

Johnfort · 07-08-2018, 08:07 AM

First thing that comes to mind is "quality of construction". Second thing is "lowest bid".

I've already replaced mine on an 11 month old unit for a slight leaking, along with the water pump and gas regulator .

Welcome to the new low in product quality.

Reminds me of the American made cars or the 80s'.

gasman6674 · 07-12-2018, 09:42 AM

Tank pressures at 100 deg can reach 196-225 psi, the hose should have handled it but as stated before low bid/low quality. You have a couple of options , replace or paint the black cover (dark colors are a very bad idea) , shut off your tanks when not being used or replace your pigtails with copper units. (available at your local LP gas Dealer)
But keep in mind even when shut off at high temps the container relief could pop due to black cover.

Johnfort · 07-12-2018, 10:19 AM

Gasman. Would a 75% fill, allowing for more vapor space reduce the gas vapor pressure on a hot day, or would the pressure be the same with all other things being equal?

(Slept through most of physics so I could be rested up for shop class.)

JohnD10 · 07-12-2018, 10:28 AM

Quote:

Originally Posted by sebaine

Has anyone else had their propane line/hose that goes from the tank to the regulator blow off?

Any thoughts on the cause and suggestions for correction?

Made in China is probably the cause...

My suggestion...replace both of those hoses with good ones!

Johnfort · 07-12-2018, 10:32 AM

Quote:

Originally Posted by Johnfort

Gasman. Would a 75% fill, allowing for more vapor space reduce the gas vapor pressure on a hot day, or would the pressure be the same with all other things being equal?

(Slept through most of physics so I could be rested up for shop class.)

Gasman. You obviously understand the rv propane system from your name and answer to the previous question. So...... what are your thoughts on the "my (appliance of your choosing) wouldn't light because there was air in the system that needed to be bled out" issue? With a properly adjusted regulator and a tight system, how would air get into the system?

Also, LP vapor does not stratify or "go bad" as long as there is at least a couple of inches of WC in the system?

What gives?

Johnfort · 07-12-2018, 10:45 AM

Quote:

Originally Posted by JohnD10

Made in China is probably the cause...

My suggestion...replace both of those hoses with good ones!

JohnD, where can you find good hoses? When I replaced mine, all I found was the same junk. Gasman has a good suggestion to replace them with copper/brass, but I like the flexability of the ?rubber? hoses.

Johnfort · 07-12-2018, 10:47 AM

I wonder if an industrial custom hose maker could tighten the crimps?

gasman6674 · 07-12-2018, 11:43 AM

Quote:

Originally Posted by Johnfort

Gasman. You obviously understand the rv propane system from your name and answer to the previous question. So...... what are your thoughts on the "my (appliance of your choosing) wouldn't light because there was air in the system that needed to be bled out" issue? With a properly adjusted regulator and a tight system, how would air get into the system?

Also, LP vapor does not stratify or "go bad" as long as there is at least a couple of inches of WC in the system?

What gives?

Liquid volume has very little affect on pressure, the exception being an overfilled tank will pop the tank relief quicker and at a lower temp. The tank relief valves are designed to go full discharge at 250 psi but will start to seep at 200 psi it is quite possible to pop a relief on a half full tank at high temps (had it happen to me)
That's why code requires a light reflecting color. You black cover may look nice but its increase the temperature of the cylinder on a really hot day.

It doesn't take much air to drop a pilot, the amount of air introduced when changing tanks could do it but I suspect most of the issues are something else.
Yes i have worked in the LP gas industry for 42 years this month.

Johnfort · 07-12-2018, 11:48 AM

Quote:

Originally Posted by gasman6674

Liquid volume has very little affect on pressure, the exception being an overfilled tank will pop the tank relief quicker and at a lower temp. The tank relief valves are designed to go full discharge at 250 psi but will start to seep at 200 psi it is quite possible to pop a relief on a half full tank at high temps (had it happen to me)
That's why code requires a light reflecting color. You black cover may look nice but its increase the temperature of the cylinder on a really hot day.

It doesn't take much air to drop a pilot, the amount of air introduced when changing tanks could do it but I suspect most of the issues are something else.
Yes i have worked in the LP gas industry for 42 years this month.

Thanks gasman. As I suspected, it's tough to get air into a charged system. Even with a tank change the air that's between the gas valve seat and the hose bud can't be very much. Seems as though it would mix with LP in the regulator?

gasman6674 · 07-12-2018, 11:52 AM

It will but again it doesn't take much to drop a pilot as they are very low btu flames .

Johnfort · 07-12-2018, 12:29 PM

That's a good point.

llr · 07-12-2018, 12:44 PM

I thought the tanks were supposed to shut down with excessive flow. If a hose coming off the regulator is not excessive I don't know what would be.

these hoses are bad, I had a small leak at the tank on one hose and a small leak at the regulator on the other hose, from our very 1st trip.

gasman6674 · 07-12-2018, 12:51 PM

Unless there is a full separation or failure the excess flow may not function. if you look at the first picture its no a full separation. Excess flows work by pressure drop and if there isn't sufficient drop they will not close. Its a catch 22 if you make them sensitive enough to stop the small leaks they would likely close every time the appliance fired

JohnD10 · 07-12-2018, 03:03 PM

Quote:

Originally Posted by Johnfort

JohnD, where can you find good hoses? When I replaced mine, all I found was the same junk. Gasman has a good suggestion to replace them with copper/brass, but I like the flexability of the ?rubber? hoses.

AAA Propane on 44th. Ave near Wadsworth in Wheat Ridge, CO.

Where I spent 2 1/2 months in my 5'ver this past winter in Wheat Ridge they serviced the RV park and I rented a 100-pound tank from them.

I was going through gas like crazy, so they inspected my system and I wound up having them fix it!

Put a much better regulator than the stock junk, and also custom made the two new hoses and a 12-foot one for the big tank.

Johnfort · 07-12-2018, 04:32 PM

I go by there from time to time. I'll check it out. Thanks.

sebaine · 07-13-2018, 02:39 PM

Quote:

Originally Posted by gasman6674

Unless there is a full separation or failure the excess flow may not function. if you look at the first picture its no a full separation. Excess flows work by pressure drop and if there isn't sufficient drop they will not close. Its a catch 22 if you make them sensitive enough to stop the small leaks they would likely close every time the appliance fired

So when I found mine leaking, it had fully separated and was spewing propane. Are you saying an "excess flow" valve should have triggered and stopped the flow? (Thanks for your input so far.)

gasman6674 · 07-13-2018, 02:55 PM

Yes by all rights it should have, but there are variables, restrictions in the hose or valve , valve not fully backseated etc
They are not always 100%

Mr Towed · 07-13-2018, 03:09 PM

Correct me if i'm wrong but the hose is AFTER the regulator, so maybe the excessive flow may not be reached due to the restriction of the regulator. This also, to me, means those hoses will never see pressures anywhere near 100 psi. I mean, even a high pressure regulator is around 30 psi, right?

What i'm a little confused about is, is the connection that came apart something that is supposed to come apart, like a screw fitting or quick release, or like a crimped fitting that is supposed to be a permanent connection?

gasman6674 · 07-13-2018, 03:23 PM

The picture is of the pigtail between the tank and the inlet of the regulator, it is tank pressure. So if you have a full failure there the excess flow should close, But excess flow by design only stop 80-90% of the flow. They have a built in weep to allow them to reset after the system is repaired. Crimp fittings are not designed to be separated.
You are correct if the hose on the outlet of the regulator fails the excess flows will never close, so its a good idea if your units in storage to close the tank valves. The pressure after the regulator is 11" wc or 6.35 oz.

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