How much refractory do I need

That will fit a standard North American propane tank.

 

That should fit but I have one that does fit from a different appliance, and the one supplied is different, if I push it hard I can get the check valve to move off the seat but not enough to start the threads. The one that works is shorter both in front of, and behind the o-ring. The fitting supplied has a sintered bronze filter so I don't want to have to machine it so I have a reply in to Vevor to see what they will do, I really don't want to have to make an adapter for the Princess Auto/Fairview fitting but with luck, the regulator end of the fitting might be just a 1/4 NPT thread.

 

I seem to remember that about 10-20 years ago, the "Fuel Gas" standard fitting (i.e. acetylene, propylene, propane, etc.) for North America changed. I don't recall exactly what the difference was, but I remember it specifically affected propane tanks. Everyone was "forced" to turn in their old tanks for ones with the "new" valve/connector. Perhaps you're dealing with a connector of the "old" type and that's why it doesn't fit? Just a guess.

In either case, I can also confirm that the current propane standard fitting also works on acetylene tanks w/o any adapters.

 

OPD valves, turn of the century (1998-2002)...makes me feel old when I say it that way

https://www.laytonco.com/what-is-opd

 

Okay, I do remember the introduction of the QCC1 fitting on things like propane barbecues etc. so if you got a new barbecue and had a tank with the old style valve, you were out of luck. But, it was my understanding (and experience to date) that the new style valves were backwards compatible with the old style fittings. However, based on your recent experience, it appears my understanding of the propane fitting situation may be flawed.

 

Vevor assured me that the fitting was the correct one but suggested their other version of that furnace withe the QCC1 fitting, my reply was that was fine if they replaced the furnace, the regulator or even the fitting that doesn't fit.

In any case, the fitting has an M14 x 1.5 thread into the regulator so a $14 fitting off Amazon, a threaded coupling and a 2" nipple that's custom threaded one end will fix the problem. Let's see what happens.