Propane leak, faulty pressure gauge, or OK?

Newsgroups Archive Prior to 2025
1

I ran a pressure test on the propane system and am wondering about the results.

Test: Open propane tank, open solenoid, run appliance (stove, water heater–done separately), turn off appliance, turn off propane tank, (keep solenoid open), note pressure gauge reading, wait several minutes, note any change in the pressure reading.

My boat has dedicated propane lines that run from the propane locker to the stove and a second line that runs from the propane locker to the water heater. Lines were professionally replaced in 2013. Most of the guts in the propane locker were replaced at that time too.

Test results: Stove

Initial psi reading: 115
Psi reading after 16 minutes: 110 (4.3% drop from initial)
Psi reading after 47 minutes: 100 (13% drop from initial)

Test results: Water Heater

Initial psi reading: 125
Psi reading after 18 minutes: 115 (8% drop from initial)
Psi reading after 44 minutes: 110 (12% drop from initial)

I tested all the connections with a bubble solution. No bubbles. I used a hand held sniffer alarm designed to pinpoint leaks at each joint. No alarm. My boat as a propane detector in the bilge which did not go off after multiple tests.

So, is all ok with these readings? If not, what else do I test?

I’m also curious why the water heater psi was higher than the stove. I ran the tests multiple times and this result always occurred. Lines are about the same length so it’s puzzling to me.

I did notice condensation in the pressure gauge dial readout. Don’t know if that has anything to do with anything.

Any suggestions or advice would be much appreciated.

Jim Cosgrove
FATE 30U #343
Galesville, MD

2

I have been told that zero drop after 10 minutes is the goal. The packing around control valve stems are often the issue. 50/50 soap and water and patience. As for the psi difference , perhaps the higher pressure is causing a large loss of gas since p and v are related.

T

3

Leak at tank connection?
Internal leak in gauge?
Appliance leaking through its shutoff or automatic valve?

4

Thanks Thor. I’ll double check around the tank. I also have a new tank I may swap in and see if that makes a difference.

Jim Cosgrove
FATE 30U #343
Galesville, MD

5

Thanks Ward. Since it’s happening on both lines, my first thought was that it’s not the appliances. I could be wrong about that of course. However the hand held detector didn’t pick up anything and the connections didn’t blow bubbles.

I do wonder about the gauge, especially with it filling with condensation. (But still the portable alarm didn’t detect a gas leak.)

I’m also going to double check the tank again and even try a new tank I have.

Thanks for your suggestions.

Jim Cosgrove
FATE 30U #343
Galesville, MD

6

You have two lines from the locker but isn’t there just a T after the regulator? Or do you have 2 regulators?

I also (and I believe every boat is the same) have the slow pressure drop after closing the tank valve. No leaks to be found anywhere but the pressure gauge at the tank goes to 0 in about 4 or 5 days. Flexible gas hose permeability is what we came up with. There have been other threads on this list on this subject. You can’t find this leak with soap or a sniffer as it is over the entire surface of the hoses. Its a very very slow leak because the hoses are at very low pressure (less than 0.5psi) after the regulator.

Close the gas valve at the tank when the appliances are not used and especially when you are away from the boat.

Tom
26C 28
Penetang

7

Thanks Tom. I appreciate the information. It’s a single regulator and solenoid which then leads to a manifold in the propane locker with a shut off for each line.

I agree completely with your cautions on using propane safely and that’s standard practice on our boat. We only turn on the propane to run the appliance and then immediately turn off the solenoid, shut the manifold switch and close the tank.

Jim Cosgrove
FATE 30U #343
Galesville MD

8

Jim,
What you could do is turn the valves to the two lines off and then charge the system from the tank to the valves. Close the tank valve and perform the leaks down test. If the system holds pressure you know the leak is after the valves.

In addition to the shut down steps you take we also burn the propane out of the lines. We turn off the tank, then open the solenoid and turn on one of the burners on the stove, light the stove and wait for the flame to burn out and then turn off the solenoid.

Mark Powers

9

Mark,
I’ll check that out—good suggestion.

You’re right that burning out the lines is good practice. I didn’t mention that but we always do that too.

Thanks,
Jim

Jim Cosgrove
FATE 30U #343
Galesville MD