Title says it all. Are corny keg QD’s universal? I have a few different cornys and I have had a very difficult time on some of the kegs getting the QD’s on and off.
Assuming you have either all ball lock or all pin lock, yes I believe so.
If you haven’t you may need to replace the 0-ring on the post. This might help.
I’ve had some be difficult, too, and that’s when I’ve replaced o-rings.
I’ve had some be very difficult and that’s when I realized I put the wrong poppet in 
On a ball-lock corny, at least, the gas and liquid QDs are not interchangeable. Or rather, they’ll work, but one will be very tight and one very loose.
Here’s everything you’ve always wanted to know about Corny Kegs from our friend Mike Dixon. :)
When I’ve had trouble it was always from having the liquid/gas posts switched. Make sure you can tell the difference between them before you put them on.
I assumed this was a Firestone/Cornelius/Challenger interchangeability question, not a goes in, goes out interchangeability question.
I have had the gas QD be difficult on some kegs. It would fit, but not lock easily. It seemed like a worn out o-ring was not allowing the QD to snap in place.
I also like to keep extra posts, o-rings and misc. keg parts on hand in the event that I have a failure. It keeps the stress level down if you know what I mean.
Thanks for the links to MD’s keg fittings–that was helpful to have all in one place. I printed it out.
Thanks to the advice of those on the forum, I’ve always only disassembled and cleaned one keg at a time to prevent interchanging posts and fittings from one keg to another. Or, that’s what I think I’ve done…
I also don’t think I’ve interchanged the gas in post for the fluid out post on a keg. But anything is possible, I guess.
How would I be able to tell anyway?
Given that there are three different types of keg posts, does that mean we’d need 3 different types of QD’s?
I’m still puzzled how an o-ring would keep me from being able to “complete the act” of securing the QD to the post. It seems like it slides on OK (2/3rds to 3/4th’s of the way) but won’t easily travel the rest of the distance to allow the QD’s locking collar to return to position. The QD also won’t rotate on the post once it gets snug. It is damn near impossible to get on and off. The bruises on my hand took a week to go away. It shouldn’t require excessive strength to get on and off. My wife would never have been able to fix this problem herself.
This sounds like you have switched the gas and liquid posts. The gas posts have horizontal cuts through the points whether it is a 6 or 12 point fitting. I think I have a picture . . . the one on the left is a liquid post, the one on the right is gas. Ignore that the left one is 6-point and the right one is 12-point, just note the cuts through the points in the one on the right. Gas.
fixed the pic
No. The portion of the post that the QD connects to is standard. The threads, the poppets, the overall height of the post itself may vary between the three, but the portion you are connecting to does not.
Other than the horizontal marks on the gas post, there are other physical differences if you look closely. I believe the flare on the liquid post is more pronounced than on the gas.
There are good photos here: Homebrew Beer Kegs
It may not be the case, it was my theory when I had this problem and changing them worked for me. My o-rings were worn and appeared to be binding when I put the QD on.
That’s happened to me too. A little keg lube on the o-ring usually fixes things.
I like to disassemble and clean all keg fittings and parts with a hot PBW solution overnight prior to sanitizing and use. I also use keg lube on the posts to extend the useful life of the orings and for ease of connection.
I use a lot of o-rings doing A/C work on cars and I’ve found that an o-ring a little too thick or fat will make two parts hard to connect and disconnect. So it’s not just the diameter of the o-ring, but the thickness of it that may be causing an issue. Keg lube should help, but the absolute best solution is a precisely sized o-ring.
Gash = gas
Level = liquid
Just got home and took a look at the posts.
I must have switched the gas and liquid posts during disassembly and cleaning.
Thanks for the clarification and the pics, Tom.
Drunkspeak.
Glad you’ve got it sorted. I’ve had them stuck on there so badly I ended up breaking the disconnect to get it off. Now if it doesn’t slip right on I double check it is the right one.