Where’s my leak?

[John4850]

Hello All,

I’ve just run some black pipe to my gas fireplace logs and I’m waiting to have a 120 pound propane tank delivered & installed.

I’ve checked the system for leaks by connecting a 20 pound propane bottle on the system and I’ve used both a hand-held electronic propane detector and soapy water and I can’t find any leaks whatsoever.

BTW, I’ve used Teflon tape and pipe dope on all of the connections per the instructions of a licensed plumber friend of mine.

I’ve also connected a Schrader valve to the system and when I put a few inches of air pressure on the system I cannot find any leaks using soapy water.

Yet, the 2 inches of pressure that I leave in the system bleads out overnight.

Does anyone have any thoughts on where I should go from here?

Obviously, I want to have a system that doesn’t leak, but I’m at a loss to discover where the leak is if I can’t find it with an electronic detector or soapy water. Is it time to call a licensed plumber in?

Thanks

 

[wooduser]

Yet, the 2 inches of pressure that I leave in the system bleads out overnight.

2" WC isn't enough.


To air test new piping, cap off the ends of the pipe and pump in 5-10m PSI and leave overnight to see if there is a significant decline in gas pressure. (when installing new gas mains which might be a mile or more in length, we pumped in 90 PSI of air and put a chart recorder on the system overnight. Even a very slight leak would be disclosed by a decline in pressure after 15 minutes or so, although finding any leak was rare) Air tests are VERY sensitive, although your 2"WC test isn't enough to see what might be happening.

To put the air in, you can install a "t" fitting with the tee going to a shutoff valve and a pipe nipple. put a gauge and a a schrader valve on the end of the tee to fill the pipe, and put a plug or cap on the system for the overnight test. Use the shutoff valve to isolate your system while you install test gauges, schrader valves or whatever. Cap off any pipe nipples for your air test ---don't rely on the valve which can leak.

You plumber friend should be able to help you with this if needed.

I’ve checked the system for leaks by connecting a 20 pound propane bottle on the system and I’ve used both a hand-held electronic propane detector and soapy water and I can’t find any leaks whatsoever.

If you have a permit, and inspector is probably going to want to see the system under a pressure test. If not, soaping out fittings and a gas detector are good substitutes. Although there is a certain art form to finding leaks with soapy solution ----which should be about 50% water and liquid dishwashing solution and painted on fitting with a paint brush or sprayed on with a hand pump sprayer.

You need to look carefully for both large bubbles and very small ones that can take five minutes or so to form.

 

[John4850]

Thanks Wooduser!

 

[wooduser]

A good way to arrange things is with the piping to be tested leading to a shutoff valve, then to a tee on which the pressure gauge is mounted and to your schrader valve to fill the system. You can read the pressure gauge to see how much air to add, then close the valve to remove the schrader valve to install a cap or plug to seal the piping.

Then you can open the shutoff valve to read the pressure for your test, and be able to read the pressure on the gauge without making any modifications while the system is under test.

 

[John4850]

Thanks wooduser,

How accurate/reliable is my Yeezou Combustible Gas Detector? If I set it where it just barely ticks, I can sometimes get it to just barely go off on my valve connection just outside of my fireplace.

I have sprayed that spot with soapy water and waited and waited and I cannot detect any leak at that location.

I would tighten that connection, but that would loosen the connection at the elbow on the other side of my nipple.

What gets me is that I’ve used a double wrap of Teflon tape and plenty of pipe dope. I’ve hand tightened all of the connections and then snugged the connection wîth a coupe of pipe wrenches. Any chance that I tightened it too tight?

 

[wooduser]

How accurate/reliable is my Yeezou Combustible Gas Detector? If I set it where it just barely ticks, I can sometimes get it to just barely go off on my valve connection just outside of my fireplace.

I have sprayed that spot with soapy water and waited and waited and I cannot detect any leak at that location.

Personally, I wouldn't worry about it. Electronic gas detectors can be VERY sensitive.

You've presumably done a quality job of soaping out the fitting and found no leak. There is no continuing odor, I presume.

You've fixed the problem.

 

[John4850]

Hello again wooduser,

I did as you suggested and placed a ball-valve right before my Schrader valve and guage. That way, I closed the valve while pumping air in and I was able to get 5 psi into the system. I then disconnected the air hose and then opened the valve and I still had 5 psi.

It’s been four hours and I still have 5 psi. Also, I bubble soaked every connection and no bubbles whatsoever.

The final test is that I opened the valve that connects to my gas logs. The only thing between it and the input to the log fixture is a 6 inch nipple. If I still have five psi in the morning, I’d say that I’m good to go.

Also, you’re correct. Throughout this process I have never smelled any propane.

 

[wooduser]

Hello again wooduser,

I did as you suggested and placed a ball-valve right before my Schrader valve and guage. That way, I closed the valve while pumping air in and I was able to get 5 psi into the system. I then disconnected the air hose and then opened the valve and I still had 5 psi.

It’s been four hours and I still have 5 psi. Also, I bubble soaked every connection and no bubbles whatsoever.

The final test is that I opened the valve that connects to my gas logs. The only thing between it and the input to the log fixture is a 6 inch nipple. If I still have five psi in the morning, I’d say that I’m good to go.

Also, you’re correct. Throughout this process I have never smelled any propane.

NOW you're cooking with GAS!

 

[John4850]

NOW you're cooking with GAS!

YeeeHaaaawww!

It’s been 17 hrs. And I still have 5 lbs of pressure in the system.

Thanks for all of your help.

John

 

[wooduser]

That's my first YeeeHaaaawww! for helping someone with a problem....!

 

[John4850]

I’m in Texas!

I wasn’t born here, but I got here as fast as I could.