Propane tanks mystery???

[Squeezle]

I just upgraded from a small travel trailer with one small propane tank to a used larger travel trailer with two large propane tanks.Yesterday I wanted to check out my oven so I turned open the valve on one of the large tanks and immediately noticed a propane smell and heard a slight hissing. I made sure the connection valve was tight and tried again..same thing, so I turned the valve off and tried the other tank...same thing, smell of propane and hissing, also check tightness of connection. I tried pouring soapy water over the valves looking for a leak but saw nothing.I then disconnected one of the tanks and replaced it with a small tank of propane I was using for my barbque.When I turned the valve no hissing or smell of propane.I then took the larger propane bottle I had removed and attached it to my barbque..no hissing.no smell of propane..I reconnected the larger tank back on the trailer and tried again...hissing..smell of propane.I tried this procedure with the other large tank on the trailer and got the same exact results. I am at a quandary as to what the problem is...at this point I ready to just replace the two larger propane tanks with two smaller one like that are on my barbque...Does anyone have any idea what could be the problem? Thank you

[DiskDoctr]

If you squirt a bit of Dawn into a cup, add a bit of hot water and use a paint brush that you agitate it with up and down to make bubbles, you can dip the bubbles onto ALL the fittings- including the ones built into the hoses.

I've found more than one hose fitting leaking over the years...and orings in the connector.

Don't forget to check the BACK of the connectors, too. Sometimes the leak can come out the back of the big black nut, not just the front.

If you find a leak on the crimped fitting into the hose (most I've seen are crimped), replace the hose. Make sure you use a thread sealant and it's pretty simple and inexpensive.

Usually box stores like Home Depot, Tractor Supply, Ace Hardware, etc stock them. Might even find a sale now that we're getting towards the end of grilling season 😉

[Squeezle]

Dutch_12078 wrote:
Are all of the cylinders using the same POL (left hand threaded, internal valve threads), or ACME (large hand tightened "nut", course external valve threads) connections?

Yes the large black plastic nut you hand tighten for the large course external valve threads

am waiting on the rain to stop to look for the leak once again.

[red31]

.

[red31]

The mystery is why you can not isolate an audible hissing!

Find the leak and fix it.

[time2roll]

Squeezle wrote:
if that was the case why would it NOT LEAK /no hissing, no smell when I attach the small propane tank to the trailer?

I think the difference is in the way you are connecting the pigtail, how it is bent or how it is stressed.

Keep looking. If you can hear it you can find it if you are persistent.
Or get a pro to look at it.

At 10+ years old I would replace the pigtails and regulator.
I recommend Cavagna brand, amazon.

[mike-s]

wa8yxm wrote:
Ok two different types of connectors to the tanks.

Bingo. The two types also have different sealing surfaces. POL originally had metal-to-metal sealing, and you needed a wrench to get it tight enough. Later, there were o-rings were added which helped some.

The newer Acme/QCC fittings have an o-ring in a different place, designed in from the start, and were made to seal when hand-tight.

POLs are more prone to leaking. That the OP's tanks don't leak with a different fitting attached, or that a different tank didn't leak makes me suspect that he has a system which has been using metal-to-metal sealing. Over time, you have to tighten them more and more to get a seal.

Question to Squeezle - does it use one of the hand-tight fittings, or do you need a wrench to connect it?

(The alternative is you just need a new o-ring)

[red31]

Ye ole pressure cuff has a stethoscope! use it.

[DiskDoctr]

Look at the end of your propane connector that goes to the tank with it disconnected. Many times the oring on the end of the connector gets old, cracks, nicks, leaks.

If so, it will leak 😉

Let us know what you find.

[wa8yxm]

Ok two different types of connectors to the tanks.

On older trailers you may still have POL (Prest-O-Light) commonly called "put on left" because of the left hand thread. this is where the "Hose" screws INTO the valve

Newer have ACME. A big plastic nut. usually green, that screws ONTO the valve.

And there are others.

THe problem is somethign called Tolerance.. Let's say there is a little tolerance in terms of the "Depth" of the valve.. And in the part of the connector that goes INTO teh valve (For that is where the seal is made)

Well if you have a 'Deep" throat (Sorry could not resist) and a short "Tong" (Likewise) you get a leak. Not supposed to (Safety valve should prevent) but well. anything made by man can fail.

[SidecarFlip]

hose is shot. Get new hoses.

[Dutch_12078]

Are all of the cylinders using the same POL (left hand threaded, internal valve threads), or ACME (large hand tightened "nut", course external valve threads) connections?

[Boon_Docker]

I had that problem with a pigtail. It would leak slightly between the rubber hose and the metal connection to the regulator. If I pushed down on the hose it would quit. Recheck (with soapy water) the connection between the hose and the connection to the regulator.

[Squeezle]

MNtundraRet wrote:
It could be the regulator itself that is leaking.

if that was the case why would it NOT LEAK /no hissing, no smell when I attach the small propane tank to the trailer?

[Squeezle]

MNtundraRet wrote:
It could be the regulator itself that is leaking.

if that was the case why would it NOT LEAK /no hissing, no smell when I attach the small propane tank to the trailer?