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Old 30-12-2014, 12:29   #1
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Any way to test empty LPG systems on old boats?

I got myself into a sailboat that's been out of the water for a few years and the propane system is empty. Is there any way to test for leaks without filling up with explosive gas? Seems a little unsafe for me to charge an un-used system after years of non-use.
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Old 30-12-2014, 12:42   #2
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Re: Any way to test empty LPG systems on old boats?

Per building codes, most tests for leaks on gas systems is done with air. So install an adaptor and pressurizing the system to 100 psig with a pressure guage attached. Let it sit for 2 hours and note any air loss. Any loss of pressure means there's a leak. You can also soap every joint and hoses to check for bubbles while the system is pressurized.
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Old 30-12-2014, 13:08   #3
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Re: Any way to test empty LPG systems on old boats?

Do not pressurize an old LPG system ! You can bet there is something flammable in there and you don't want it escaping inside the boat.

Bite the bullet and replace the lines, solenoid and pressure gauge. It will cost you less than $100 and take all the questions out of the equation.
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Old 30-12-2014, 13:48   #4
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Re: Any way to test empty LPG systems on old boats?

There just isn't enough volume in the lines even if they were full of 100% propane to be dangerous. Hasn't been used in yrs, how could there be explosive gas still there?
But I think your point to replace at least the flexible lines is valid. I believe the copper line in my gas line may well outlast the boat, corrosion is I think the only issue there and at 27 yrs old, I can't find any significant corrosion
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Old 30-12-2014, 13:51   #5
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Re: Any way to test empty LPG systems on old boats?

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There just isn't enough volume in the lines even if they were full of 100% propane to be dangerous. Hasn't been used in yrs, how could there be explosive gas still there?
But I think your point to replace at least the flexible lines is valid. I believe the copper line in my gas line may well outlast the boat, corrosion is I think the only issue there and at 27 yrs old, I can't find any significant corrosion
LPG is heavier than air. It can settle in the bottom of the tank and low spots in the lines.

27 yr old copper lines should not be trusted either. Copper over tempers with vibration and becomes brittle (learned this one the hard way) and can fracture.

It's just not worth taking the chance.
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Old 30-12-2014, 14:12   #6
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Re: Any way to test empty LPG systems on old boats?

I agree with a64. Just hook up a tank, turn the solenoid on, turn the gas valve on and as soon as the line is pressurized (ie. the gauge stops rising, which should be pretty much instantly), shut the valve off. If three hours later that line has not lost pressure you're good. If it's lost pressure, then you have a leak you need to find, and all of a pint of gas has escaped somewhere which is negligible.
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Old 30-12-2014, 14:32   #7
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Re: Any way to test empty LPG systems on old boats?

I didn't mean to say test with propane, but truthfully, isn't that why we have a pressure gauge, so that you can test, otherwise it's useless?
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Old 30-12-2014, 14:33   #8
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Re: Any way to test empty LPG systems on old boats?

Ditto with Suijin and a64.
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Old 30-12-2014, 14:35   #9
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Re: Any way to test empty LPG systems on old boats?

You know I guess if it's hard copper, which mine isn't it could work harden, but what's going on to cause that?

Bottom line, if you want to replace the entire hose, why not?
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Old 30-12-2014, 14:52   #10
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Re: Any way to test empty LPG systems on old boats?

Make sure the electrical system is disconnected and there are no open flames or other ignition sources and just hook up a tank.

At that point, open it up then close and see if the guage holds pressure. If there is no obvious loss of pressure follow the lines around with soapy water and check for leaks. There isn't enough gas in the lines to be a big concern and you will be driven out by the smell before it gets bad.

Or as others have suggested go ahead and replace the lines.

FYI - any solid copper line can work harden over time. When a vibration moves the line, it bends ever so slightly. The next vibration bends it ever so slightly again. The bending tends to move back and forth in the same place so you don't see any change. Over time this bending work hardens the line.
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Old 31-12-2014, 10:55   #11
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Re: Any way to test empty LPG systems on old boats?

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Originally Posted by critter View Post
I got myself into a sailboat that's been out of the water for a few years and the propane system is empty. Is there any way to test for leaks without filling up with explosive gas? Seems a little unsafe for me to charge an un-used system after years of non-use.
If you are really concerned sailorchic34's suggestion makes the most sense. A 100psi sounds high to me but may include a safety factor. If you redo in copper tube just keep in mind it isn't the same as waterline tubing wall thickness is more. Code here specifies flare fittings why ?.
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Old 31-12-2014, 11:02   #12
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Re: Any way to test empty LPG systems on old boats?

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Code here specifies flare fittings why ?.
psi increases with temperature. at 100 degrees LPG can reach 200psi.
An ounce of propane at that pressure can make a pretty big bang.
Gear clamps on a garden hose fuel line won't cut it.
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Old 31-12-2014, 11:21   #13
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Re: Any way to test empty LPG systems on old boats?

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psi increases with temperature. at 100 degrees LPG can reach 200psi.
An ounce of propane at that pressure can make a pretty big bang.
Gear clamps on a garden hose fuel line won't cut it.
I doubt the low side past the regulator is any place close to 100psi. I could well be wrong. I had a pro ask if I had a book of matched, he actually checked a fitting that way. Crazy!

I bought a boat that had just that a hose clamp holding a hose to the stove. A foot and bulkhead from their infant's bunk. Crazier.

Point being, be careful not paranoid. Or maybe overly careful with a heavier than air inside a bucket.
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Old 31-12-2014, 11:28   #14
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Re: Any way to test empty LPG systems on old boats?

The low side of the typical LP regulator is normally set at 11" w.c. (water column) which is roughly 1/3 of 1 PSI. ABYC says test with 5 PSIG. BUT, a regulator can fail over time and can fail open (rare, but it can happen) where you receive full tank pressure. So 100 psig test allows for that failure.
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Old 31-12-2014, 11:44   #15
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Re: Any way to test empty LPG systems on old boats?

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The low side of the typical LP regulator is normally set at 11" w.c. (water column) which is roughly 1/3 of 1 PSI. ABYC says test with 5 PSIG. BUT, a regulator can fail over time and can fail open (rare, but it can happen) where you receive full tank pressure. So 100 psig test allows for that failure.
Thanks for the explanation 5-7psi stuck in my mind. I had a regulator fail. Fortunately on a back yard grill. Made a hell of a blaze. Burnt the **** out if my hand throwing the tank away from the house. Hose you say? It was gone. Upon inspection, regulator appeared to be the casualty of a neighbors kids BB Gun not a normal failure.
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