Is there a gas leak?

[FionaJC]

Boat in the UK

I am paranoid about gas. 1 have a 24/7 gas detector in the bilge.

I had a two bottle system, vented outside, with a change over switch (shown below) and manometer gauge. I would turn off at the bottles and next time I went back to the boat I to the gas the gauge would show empty. As soon as I turned on the gas I would hear a psssssh and the gauge would show full again.

No joins bubble with soapy water and the cooker was professionally serviced.

Being paranoid I changed over to a single regulator without a guage. Still get the pssssssh though.

I use a 15Kg butane on a 4 burner BBQ at home. It seems I cook twice and its empty (same psssssh, but I usually leave it turned on on the connector)

I now have a 3.9Kg Propane (spare off the boat) running a six burner BBQ I tried it out and then five days later it ran for 30 minutes and went out.

Now my question and I don't think I have a leak, will a system naturally de-pressurise even when its off? or should it stay pressurised over a few days? No speculation or Ive read answers please, I can look things up too and I cant find any information on this. Most LPG suppliers wont help when I mention boat and others charge a fortune. I need an expert opinion please.

[boatpoker]

Yes, sounds like a leak. Our propane system with two 20lb. bottles (and gauge) keeps pressure for weeks.

[FionaJC]

Originally Posted by boatpoker

Yes, sounds like a leak. Our propane system with two 20lb. bottles (and gauge) keeps pressure for weeks.

Thanks that's what I wondered. I assume that you have a gauge and turn it off at the bottle?

[boatpoker]

Originally Posted by FionaJC

Thanks that's what I wondered. I assume that you have a gauge and turn it off at the bottle?

We are full time liveaboards. Our bottles are almost never turned off. We have a solenoid shut-off switch near the galley.

We only close the bottles if we'll be away from the boat for a few days.

[Peeew]

I do the standard technique of ending my cooking by turning off the solenoid and waiting for the flame to go out before turning burner to off. And occasionally will turn the burner off first, wait a day, and then with a flame at the burner will turn the burner on. If I get a short lived flame there is no leak between solenoid and stove. If I don’t get a bit of gas/flame then I do have a leak somewhere.

[billgewater]

Cooking gas is potentially very dangerous. You can expire from breathing it or for more excitement, a violent explosion with crew cartwheeling through the air, followed by a ripping fire. Then just to add to your woes, a recalcitrant, difficult insurance company stand off.
I do recommend the installation of a gas detector with one sensor just under the cooker and one in the lowest bilge area with an alarm and an automated solenoid cut off at the bottles. We always turn the unit off after use and then back on prior to ignition when it goes through the testing phase - which takes about twenty seconds. Also I noticed that you have a single stage regulator. In some places the two stage ones are mandatory. For good reason.
After the regulator, the gas pressure is actually very low (less than 1 psi). A little trick is to install a testing point inlet after the regulator that allows you to pump up the system with air from a (say) a foot pump to about 30 or so psi. (you may need to put in a stop cap or a manual valve to prevent this pressure from being exposed to the output side of the regulator. I have heard that some regulators don't like high pressure at the outlet. You don't want to damage your regulator.) This will safely reveal any leaks in the system much more conspicuously than the lower gas pressure will. If there are any leaks at any flare fittings, you can just slack off the fitting and re tighten it until the leak stops. Not advisable if there is still gas in the system.

Another safety aid is the installation of a manual cut off near the cooker and use it every time you use the cooker. If there is a flare up at the cooker (e.g. cooking oil ignites) and you can't reach the normal controls, then this manual cutoff (situated a short distance from the cooker) allows you to save the day, the boat, the food and importantly, your social standing as a reliable chef. (One with "flare"?)

Finally, consider installing a bilge vacuum system with a 12 vdc flame proof motor. Not expensive, but if you do have a gas spill, then you will definitely need one and there are no chandlers at sea. Some propellant gases from hair sprays, insect repellents, carbon monoxide from engine exhaust gases etc. can also accumulate in the bilge so regularly vacuuming is a good practice in keel boats. The larger the bilge, then the more gas can accumulate so the more important this vacuuming becomes.
Consult a qualified marine gas installer. Get certification that the system meets legal requirements and file it with your insurance company.

[boatpoker]

Originally Posted by billgewater

Cooking gas is potentially very dangerous. You can expire from breathing it or for more excitement, a violent explosion with crew cartwheeling through the air, followed by a ripping fire. Then just to add to your woes, a recalcitrant, difficult insurance company stand off.
I do recommend the installation of a gas detector with one sensor just under the cooker and one in the lowest bilge area with an alarm and an automated solenoid cut off at the bottles. We always turn the unit off after use and then back on prior to ignition when it goes through the testing phase - which takes about twenty seconds. Also I noticed that you have a single stage regulator. In some places the two stage ones are mandatory. For good reason.
After the regulator, the gas pressure is actually very low (less than 1 psi). A little trick is to install a testing point inlet after the regulator that allows you to pump up the system with air from a (say) a foot pump to about 30 or so psi. (you may need to put in a stop cap or a manual valve to prevent this pressure from being exposed to the output side of the regulator. I have heard that some regulators don't like high pressure at the outlet. You don't want to damage your regulator.) This will safely reveal any leaks in the system much more conspicuously than the lower gas pressure will. If there are any leaks at any flare fittings, you can just slack off the fitting and re tighten it until the leak stops. Not advisable if there is still gas in the system.

Another safety aid is the installation of a manual cut off near the cooker and use it every time you use the cooker. If there is a flare up at the cooker (e.g. cooking oil ignites) and you can't reach the normal controls, then this manual cutoff (situated a short distance from the cooker) allows you to save the day, the boat, the food and importantly, your social standing as a reliable chef. (One with "flare"?)

Finally, consider installing a bilge vacuum system with a 12 vdc flame proof motor. Not expensive, but if you do have a gas spill, then you will definitely need one and there are no chandlers at sea. Some propellant gases from hair sprays, insect repellents, carbon monoxide from engine exhaust gases etc. can also accumulate in the bilge so regularly vacuuming is a good practice in keel boats. The larger the bilge, then the more gas can accumulate so the more important this vacuuming becomes.
Consult a qualified marine gas installer. Get certification that the system meets legal requirements and file it with your insurance company.

Don't listen to this guy !

[chris95040]

Originally Posted by boatpoker

We are full time liveaboards. Our bottles are almost never turned off. We have a solenoid shut-off switch near the galley.

We only close the bottles if we'll be away from the boat for a few days.

Then how do you know you hold pressure ‘for weeks’?

You could have slow leaks but since the bottles are still plumbed in it’ll keep the pressure up. And even with the solenoid shut that gizmo is not as reliably leak tight as turning the knob on the tank.

The OP is doing a rather intelligent test by closing the tank and expecting the system to remain in the same state for a period of time. And it should. Their symptom is consistent with a leak.

OP, maybe it’s time to replace any flexible hoses, etc? Maybe cap off the system somewhere and start identifying what leaks and what doesn’t. I’d start with the oven, disconnect it and cap the line. Or perhaps immediately after the regulator.

[boatpoker]

Originally Posted by chris95040

Then how do you know you hold pressure ‘for weeks’?

Not sure you understand how a pressure gauge works and where it is placed in the system

A properly instsalled and well maintained system as a full time liveaboard for 30 years I've ever had a problem maintaining pressure. If you cannot maintain pressure over long periods you have done something wrong.

In all this time I have had one failed regulator and two failed solenoids. In these cases leaks were directed overboard through a properly designed propane locker as per ABYC Standards..... no threat to crew or vessel.

[donradcliffe]

If you close the tank valve and turn off the appliances, the pressure will drop off if there are ANY leaks in the system. It may take 15 seconds or a year for the pressure to go to zero. You can get an idea of the pressure drop vs time by lighting one burner in the cooker, then closing the tank valve and noting how fast the pressure drops. If you are seeing a pressure drop like this after closing the tank valve without a burner on, don't light any matches or flip any switches for 15 minutes--you have a VERY serious leak.

In my experience, a leak which drops the pressure by 10 psi in 30 minutes can be easily be detected by soapy water, and needs to be fixed. If you can't find it on the regulator, solenoid, or any of the joints, it could be inside your professionally maintained cooker--disconnect the cooker and cap the line and test again before you start tearing apart the cooker.

If the pressure drops by less than 10 psi in 24 hours, this is below the limit of concern, and at times can be explained by temperature differences. In any case, I turn off the tank valve whenever I leave the boat for more than a day.

[Boatyarddog]

Originally Posted by chris95040

Then how do you know you hold pressure ‘for weeks’?

You could have slow leaks but since the bottles are still plumbed in it’ll keep the pressure up. And even with the solenoid shut that gizmo is not as reliably leak tight as turning the knob on the tank.

The OP is doing a rather intelligent test by closing the tank and expecting the system to remain in the same state for a period of time. And it should. Their symptom is consistent with a leak.

OP, maybe it’s time to replace any flexible hoses, etc? Maybe cap off the system somewhere and start identifying what leaks and what doesn’t. I’d start with the oven, disconnect it and cap the line. Or perhaps immediately after the regulator.

Seems the amount of propane pressure, is some what dependent on temp, a loss of even 100 psi of Propane over a "couple of weeks" being enough to explode is stretching it a bit.
Worth checking it out though, as a leaking intermittent solenoid valve is possible.
SV Cloud Duster

[Pete7]

Originally Posted by FionaJC

Boat in the UK

I am paranoid about gas. 1 have a 24/7 gas detector in the bilge.

I had a two bottle system, vented outside, with a change over switch (shown below) and manometer gauge. I would turn off at the bottles and next time I went back to the boat I to the gas the gauge would show empty. As soon as I turned on the gas I would hear a psssssh and the gauge would show full again.

No joins bubble with soapy water and the cooker was professionally serviced.

Being paranoid I changed over to a single regulator without a guage. Still get the pssssssh though.

I use a 15Kg butane on a 4 burner BBQ at home. It seems I cook twice and its empty (same psssssh, but I usually leave it turned on on the connector)

I now have a 3.9Kg Propane (spare off the boat) running a six burner BBQ I tried it out and then five days later it ran for 30 minutes and went out.

Now my question and I don't think I have a leak, will a system naturally de-pressurise even when its off? or should it stay pressurised over a few days? No speculation or Ive read answers please, I can look things up too and I cant find any information on this. Most LPG suppliers wont help when I mention boat and others charge a fortune. I need an expert opinion please.

Fiona, bit confused about the sentences in red, is this on the boat or at home? even so you can't use that much gas unless you're a farrier.

When did you last check the gas detector?

I think you need a gas safety engineer (formerly Corgi) to check it out. I know, rare as rocking horse pooh

Was the cooker service recent? if so get him back to check it , since you have changed the hose and regulator it ought not to be this, which leaves the cooker, unless there is another tap. We have brass on/off tap under the cooker, never use it but it's there.

Oh and ours depressurises over a few days too.

[cal40john]

OP wrote: I would turn off at the bottles and next time I went back to the boat the gas gauge would show empty.

I do the test described below and have let it run a lot longer than 3 minutes, as much as a 1/2 hour with no pressure drop which ABYC seems to consider that there isn't a leak. When I come back to the boat in a week with the tank valve off the pressure gauge reads zero.
(I do one extra bit, I watch the gauge as I turn the tank valve back on after the test to see if the gauge twitches.)

https://www.practical-sailor.com/blo...-propane-leaks

LPG systems are also required to have a pressure gauge installed on the cylinder side of the pressure regulator. This gauge allows you to quickly and easily check the system for leaks via a leak-down test. To conduct a leak-down test, turn on the stove or grill, then close all the burner valves, leaving the solenoid switch on. Note the pressure gauge reading, then close the tank valve – the gauge reading should remain constant for at least three minutes. If the pressure drops, then you have a leak (or leaks) and must inspect the entire system before using it again.

[billgewater]

Originally Posted by boatpoker

Don't listen to this guy !

You may not wish to listen to my suggestions but some of them are compulsory in Queensland.

The installation MUST be done by a certified marine gas installer.
There must be a testing fitting after the regulator.
The regulator must be a two stage model.
There must be a manual cut off near the cooker. (unless it is all certified copper tubing - no flex tubing - to the appliance.)

For charter vessels they are all absolutely compulsory and the system must be checked every year by a certified marine gas installer.

This is not my opinion. These are conditions for Queensland vessel registration.

I have spoken to a number of Queensland marine gas installers and the use of a two sensor alarm system that operates a cut off solenoid in the high pressure side is strongly advised. Bilge vacuuming systems are just common sense.

Furthermore, in QLD and I believe the other states as well, the copper tubing must be a specific type of tubing and it is covered with a plastic tubing for mechanical protection. Green for half inch brown for three eighths. Again, this is not optional.

Visiting boats do not need to comply. Do all Queenslanders comply? I am sure they all don't, but them's the rules.

[donradcliffe]

The rules are written by the fitters societies for the fitters benefit, and in Queensland they are not reasonable rules. I believe you poor bastards can't wire your own houses, and HAVE to wear bicycle helmets too.

The rules on our large island say you CAN't have a manual cut off near the cooker. I don't think that's reasonable either, but them's the local rules.

The OP does have a gas sensor that alarms, but she didn't mention whether it was hooked to a solenoid cutoff. I believe that is a reasonable rule, even though the sensors get over zealous in time and have to be replaced. However, I've been on new boats that don't have one. My RV has a sensor alarm but no solenoid and no manual cutoff--better lobbyists, different rules.