The pigtail to one of my propane tanks has cracks in the hose, so I want to replace it.When I put in the new one, it flunks the soap bubble test. There are bubbles between the brass fitting on the end of the hose and the brass fitting on the regulator.The new one’s package reads “RV Thermo Pigtail 1/4” Inverted Flare”.If I switch back to the old one, it works fine.Is there some trick to changing these?

Not sure. Why not take it to your local Blue Flame or other propane shop and ask them? I've used the BF shop guys before to make up custom hoses and parts for me. They're great.

Instead of a 'flared fitting' I would imagine your LP Reg needs an 'Inverter' fitting

There are at least two different type fittings. Years ago I replaced my high pressure regulator valve and the old pigtail would not fit it. Had to take the fitting from the old regulator and install it on the new one. You might be able to buy an adapter. Check your local well equipped hardware store.

Do the fittings look identical in shape as to the mating surfaces that seal together? That is the replacement hose should look identical to the old hose.Use no sealant tape right?I believe most common is the inverted flare but some could be NPT threads.

IIRC inverted flare uses straight threads.I stopped buying pre-made pigtails. Whether they have a pipe thread or reverse flared end both ends of the hose use crimped fittings with barbs. I always had problems with propane leaks between the hose and the fitting. Especially when the hoses got stiff in the winter time and I was switching tanks. The hoses would always rotate a little on the barbs because they were so stiff. I now get my hoses made at a local industrial hose supplier. I took the reverse flare fittings out of the regulator and put in pipe threaded by 45 degree flared elbows and bought green acme nut fittings with male pipe threads on them.The hoses I have made have a female 45 degree flared swivel on one end and a female pipe thread on the other end. Although they have the same internal diameter, the hoses are a little fatter and the crips are a lot tighter. No more leaks or hoses rotating on the crimped hose barb's.

Replacing a propane pigtail | Good Sam Community

trailrider
Explorer
Aug 14, 2019
Inverted flare trick. Tighten it and loosen it. Repeat a few times and it will seal. Sometimes the initial tightening on a new fitting will leak.
opnspaces
Navigator II
Aug 14, 2019
Thanks for the link, I'll have to look at my hose end the next time the camper comes home.
waynefi
Explorer
Aug 14, 2019
opnspaces wrote:
Can you provide the Amazon link for the one that worked for you? I'm thinking about replacing mine.

The one I got is aShinestar 12in RV propane connector.

This is an inverted flare connector. I think that the way you tell them from an NPT is that looking into the end of the connection, the tube walls are beveled, not straight pipe.

On the one I had trouble with, the leak was between the brass on the end of the pigtail and the brass on the regulator.
opnspaces
Navigator II
Aug 13, 2019
Can you provide the Amazon link for the one that worked for you? I'm thinking about replacing mine.
dougrainer
Nomad
Aug 13, 2019
Usually the Pigtails that have a round crimp ring will leak. You want the compressed fitting. The link shows the best crimp. Doug

https://www.walmart.com/ip/Camco-Olympian-Heavy-Duty-24-Propane-Pigtail-Connector-Carded-Pack/29764657?wmlspartner=wlpa&selectedSellerId=17812&adid=22222222227021475804&wl0=&wl1=g&wl2=c&wl3=40839465512&wl4=pla-78652631912&wl5=9027262&wl6=&wl7=&wl8=&wl9=pla&wl10=125207231&wl11=online&wl12=29764657&veh=sem&gclid=EAIaIQobChMIh7f_jaeA5AIVSb7ACh1S_QpZEAQYAyABEgJ5hvD_BwE
waynefi
Explorer
Aug 13, 2019
I took the leaky one back and exchanged it for another of the same brand. It also leaked. So I returned that and ordered from Amazon. That one does not leak.

The original, from an RV dealer, cost $30 for one, and leaked. From Amazon, it was $15 for two, and no leak.
time2roll
Nomad
Aug 08, 2019
Should not be any trick to it. Snug it up firm and it should seal.
Possible defective.

I recommend Cavagna brand for a superior crimp.

https://www.rvplus.com/lp-gas/pigtails-gas-hoses-and-accessories/pigtails/

Verify part number on page 90
waynefi
Explorer
Aug 08, 2019
time2roll wrote:
Do the fittings look identical in shape as to the mating surfaces that seal together? That is the replacement hose should look identical to the old hose.

Use no sealant tape right?

I believe most common is the inverted flare but some could be NPT threads.

Yes, the old and new ones look identical. No sealant tape.

The box the new one came has no instructions at al about screwing it in.
mobeewan
Explorer
Aug 08, 2019
IIRC inverted flare uses straight threads.

I stopped buying pre-made pigtails. Whether they have a pipe thread or reverse flared end both ends of the hose use crimped fittings with barbs. I always had problems with propane leaks between the hose and the fitting. Especially when the hoses got stiff in the winter time and I was switching tanks. The hoses would always rotate a little on the barbs because they were so stiff. I now get my hoses made at a local industrial hose supplier. I took the reverse flare fittings out of the regulator and put in pipe threaded by 45 degree flared elbows and bought green acme nut fittings with male pipe threads on them.

The hoses I have made have a female 45 degree flared swivel on one end and a female pipe thread on the other end. Although they have the same internal diameter, the hoses are a little fatter and the crips are a lot tighter. No more leaks or hoses rotating on the crimped hose barb's.
time2roll
Nomad
Aug 08, 2019
Do the fittings look identical in shape as to the mating surfaces that seal together? That is the replacement hose should look identical to the old hose.

Use no sealant tape right?

I believe most common is the inverted flare but some could be NPT threads.