Leak checking propane system

[MarkSF]

I just finishing updating the propane system including installing a new Trident regulator, new pigtails and bottles, and Xintex leak detector / solenoid valve.

When I leak check the system I get a drop from 128 to 124 PSI with the solenoid valve closed, over 20 minutes.

With the valve open, I get a drop to 120 PSI, also over 20 minutes.

The official leak test in the ABYC code states "no drop over 3 minutes", which I would pass.

Can anyone tell me if these slight drops over the longer time are normal?

I leak checked all fittings and joints several times with soap suds, nothing.

[overbored]

in 20 minutes you may be seeing the effect of temperature change. are you using soap or a real leak check fluid there is a differance when it comes to very small leaks

[MarkSF]

I am using dish detergent, a little in a bottle with some hot water. Give it a good shake.

As well as any temperature change, there is the matter of the pipes being slightly elastic. Now, I just turned the system on, with brand new components, and did the leak check. The instructions I've found involve using the stove for a while, presumably to give the hosing time to settle, then doing the leak check.

Will try again with appropriate settling time first.

[INMA]

I can't suggest what would be a reasonable leak rate, I am not a fan of LPG on yachts.

Remembering the solenoide valve and other valves will leak to some extent there are two leakage rates to consider, after commissioning and in service (after a few months).

Do the pressure monitoring for 24 hours, there will be an initial change then if the system is intact, a very slow leak rate should occur over the longer time. Keep an eye on temperature but I would not expect huge changes due to temperature.

If you know how the system held after commissioning, you should be able to see the changes due to wear or failures which are probably more important long term.

Check your gas detectors were calibrated for propane and make sure they are near the floor.

One other feature that can be valuable is a vent valve to release any pressure from the line near the cylinder manual shutoff. The vent can be opened to assure no pressure is in the system after the cylinder is closed, vent valves can be in the form of a line filter or a traditional valve, as long as dumped gas is ejected safely. Its handy to know the line is vented when leaving the yacht at anchor or when a fault occurs while underway.

[MarkSF]

Originally Posted by INMA

I can't suggest what would be a reasonable leak rate, I am not a fan of LPG on yachts.

Remembering the solenoide valve and other valves will leak to some extent there are two leakage rates to consider, after commissioning and in service (after a few months).

Do the pressure monitoring for 24 hours, there will be an initial change then if the system is intact, a very slow leak rate should occur over the longer time. Keep an eye on temperature but I would not expect huge changes due to temperature.

If you know how the system held after commissioning, you should be able to see the changes due to wear or failures which are probably more important long term.

Check your gas detectors were calibrated for propane and make sure they are near the floor.

One other feature that can be valuable is a vent valve to release any pressure from the line near the cylinder manual shutoff. The vent can be opened to assure no pressure is in the system after the cylinder is closed, vent valves can be in the form of a line filter or a traditional valve, as long as dumped gas is ejected safely. Its handy to know the line is vented when leaving the yacht at anchor or when a fault occurs while underway.

There was some internal debate about where to put the leak sensor, in the end I put it low down in the bilge, but not so low it gets wet. I thought about putting it above the cabin floor but didn't. My argument is I can smell a major leak in the cabin, but not a slow build up in the bilge.

[mitiempo]

Any leaks in the propane locker itself will drain through the locker vent and cannot leak into the boat if it is installed as it should be. I have seen many propane lockers that have the smell of propane inside - a small leak but large enough to be noticed. The parts to worry about are the feed lines to the stove and any other appliances on the boat and their connections at those appliances. The only connections outside of the vented propane locker should be at the stove or other appliance. If there is a stove and a heater they have to have their own feed lines, continuous from the propane locker with all connections inside the locker, not T'ed outside of the locker.

I have installed quite a few propane detectors. If there is only a stove I usually put the sensor under the stove. If the bilge is deep a second sensor can be installed there. In my boat the bilge is so shallow I only have a sensor under the stove. The detector I install is here Propane Leak Detectors for Boats and RVs and is designed for 2 sensors. It is available with and without the solenoid control - I prefer it with.

[MarkSF]

Originally Posted by mitiempo

Any leaks in the propane locker itself will drain through the locker vent and cannot leak into the boat if it is installed as it should be. I have seen many propane lockers that have the smell of propane inside - a small leak but large enough to be noticed. The parts to worry about are the feed lines to the stove and any other appliances on the boat and their connections at those appliances. The only connections outside of the vented propane locker should be at the stove or other appliance. If there is a stove and a heater they have to have their own feed lines, continuous from the propane locker with all connections inside the locker, not T'ed outside of the locker.

I have installed quite a few propane detectors. If there is only a stove I usually put the sensor under the stove. If the bilge is deep a second sensor can be installed there. In my boat the bilge is so shallow I only have a sensor under the stove. The detector I install is here Propane Leak Detectors for Boats and RVs and is designed for 2 sensors. It is available with and without the solenoid control - I prefer it with.

This is the one I installed.

S-1A Propane and CNG Fume Detector from Fireboy-Xintex

There is one continuous line to the stove from the locker, which drains outside.

[mitiempo]

Xintex is good. The one I linked to is made locally and very popular around here.

You purchased the one without solenoid control? What I like about the Electro Systems unit with solenoid control is not only does it not need a separate switch for the solenoid, but if it detects a leak it will close the valve.

[MarkSF]

No, I got the one with solenoid, and it works as you described - any leak and it closes the valve. Tested it with an unlit lighter and it works great.

[INMA]

Mark, it is not a leak detector but a gas detector.

There is a difference, if gas gets in the bilge for any reason, the detector should alarm.

Alternate sources of gas could be a faulty burner not combusting all the gas or any other source of hydrocarbon like your cigarette lighter.

Its important to understand the alarm can go off for many different reasons.