How to pressure check propane system

[JackMS]

Trying to pressure check my propane system after doing some repairs. Thought I would just blow air pressure into my auxiliary connection. The regulator is leaking as fast as I can put the air in-almost. Is this normal when putting pressure backward into the regulator or do I have a regulator problem?

The original problem was that the solenoid valve was not working and tank was full. Don’t use propane much so after a few years I decided to fix it and found tank empty, so there is a leak somewhere. I fixed the valve but want to check system before putting propane back in. Propane makes me a little nervous so I am a little overly cautious maybe. Just not fond of big booms

[Dutch_12078]

Stim wrote:

dougrainer wrote:

Stim wrote:
DO NOT PUT HIGH PRESSURE AIR IN THE TANK!!!
Look up how a diesel engine works. Fuel, compression, ignition.
There will be residual LP fumes in the tank even after 20 years.
I have welded/repaired fuel/gas tanks for years.
Even climbed into tanker trailers to do it.
You have to know what you are doing.

They use high pressure air to QC the tanks after build. They also leave that air in them from the RV OEM, and the LP filler must drain and purge the tanks at first fill. Both ASME and DOT have hi pressure air in them. So, the OP puts in air and verifies the fix then has the LP filler drain and purge and fill. As YOU stated, you have to know what you are doing, which on LP you do not. There is no problem injecting air pressure into the tank to check the system without having to install LP and then drain if the problem is at the tank itself. Doug

The problem with your post is that NEW tanks have never had combustible products stored in them!
If you can't "Clear" a used tank then you can use an inert gas like nitrogen
to pressurize it.
Perhaps it is you that don't have the experience because you overlooked the obvious.

Are you aware that used DOT cylinders can be recertified using a "proof-pressure" test that subjects them to air pressure at double the rated service pressure? Cylinders recertified by the proof-pressure method don't need recertifying again for 7-10 years instead of 5 years for visual recertifications.

DOES MY L/P TANK NEED TO BE RE-CERTIFIED?

[Stim]

dougrainer wrote:

Stim wrote:
DO NOT PUT HIGH PRESSURE AIR IN THE TANK!!!
Look up how a diesel engine works. Fuel, compression, ignition.
There will be residual LP fumes in the tank even after 20 years.
I have welded/repaired fuel/gas tanks for years.
Even climbed into tanker trailers to do it.
You have to know what you are doing.

They use high pressure air to QC the tanks after build. They also leave that air in them from the RV OEM, and the LP filler must drain and purge the tanks at first fill. Both ASME and DOT have hi pressure air in them. So, the OP puts in air and verifies the fix then has the LP filler drain and purge and fill. As YOU stated, you have to know what you are doing, which on LP you do not. There is no problem injecting air pressure into the tank to check the system without having to install LP and then drain if the problem is at the tank itself. Doug

The problem with your post is that NEW tanks have never had combustible products stored in them!
If you can't "Clear" a used tank then you can use an inert gas like nitrogen
to pressurize it.
Perhaps it is you that don't have the experience because you overlooked the obvious.

[dougrainer]

Stim wrote:
DO NOT PUT HIGH PRESSURE AIR IN THE TANK!!!
Look up how a diesel engine works. Fuel, compression, ignition.
There will be residual LP fumes in the tank even after 20 years.
I have welded/repaired fuel/gas tanks for years.
Even climbed into tanker trailers to do it.
You have to know what you are doing.

They use high pressure air to QC the tanks after build. They also leave that air in them from the RV OEM, and the LP filler must drain and purge the tanks at first fill. Both ASME and DOT have hi pressure air in them. So, the OP puts in air and verifies the fix then has the LP filler drain and purge and fill. As YOU stated, you have to know what you are doing, which on LP you do not. There is no problem injecting air pressure into the tank to check the system without having to install LP and then drain if the problem is at the tank itself. Doug

[time2roll]

I use a combustible gas detector to check fittings after service.

Something like this should work:

https://www.amazon.com/SGILE-Natural-Detector-Combustible-Sniffer

[Stim]

DO NOT PUT HIGH PRESSURE AIR IN THE TANK!!!
Look up how a diesel engine works. Fuel, compression, ignition.
There will be residual LP fumes in the tank even after 20 years.
I have welded/repaired fuel/gas tanks for years.
Even climbed into tanker trailers to do it.
You have to know what you are doing.

[Dutch_12078]

Unless the leak is in the tank or the service valve attached to the tank, there won't be any need to bleed it back out if a leak is found elsewhere. And if you put any air in the tank, the tank will need to be properly purged before filling it with LP.

[JackMS]

When my tank was still full, my local propane place told me to just break a hose loose and let the propane go because that is all they could do. So I won’t be taking to them. I can put a little air pressure in and get some leak solution like Doug suggested once I get my new regulator in. I hate to put any propane in because I may have to just let it back out to fix the leak. Or worse yet, have the leak be bigger than I think and find it while putting propane in. Thanks for the responses. Always good info here.

[ScottG]

There's enough pressure with the propane to check for leaks. Just use some Windex which bubbles like crazy where ever there's a leak.

[ksg5000]

In my area you could bring your rig down to a commercial propane dealer who would fix your problem for a nominal charge so long as let them fill your tank. Just another alternative.

[JackMS]

Thanks Doug. I’ll just say it is probably a good idea to replace the 13 year old regulator anyways. Won’t hurt so bad after I break out the wallet

[dougrainer]

1. You CANNOT blow back air pressure in the system. The working PSI pressure of a LP system is about .4(yes .4) PSI or 11.5 inches Water column pressure.
2. YOU HAVE DESTROYED THE REGULATOR
3. If the tank is empty, you CAN use a high pressure air nozzle to put air into the LP tank at the regular fill port for the tank to get enough pressure to test the system. Then bleed the air completely out after you test and find and fix the leak.
4. To find the leak you do a Manometer leak down test. To check various connections you use an approved LP bubble leak test solution. Soapy water is a No No. It is caustic to copper and brass fittings. Doug