That is a real problem. Too soft orings can also result in leaks and failures. I have seen it before more than once. If you know it to be true then just fix it.
Din Retainer / Hand Wheel Loosening?
- Thread starter rob.mwpropane
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OP
It might be. The one I have in there might be a 70, but I could also be wrong about that. I don't think it felt like a 90.
I just had this issue a couple of months ago. I accidentally put a softer oring inside one of my 1st stage dins and it was popping when I first opened the valve. Seems like it might have burst eventually.
halocline
Contributor
It really depends on how the o-ring is situated. If it’s captured in the end of the DIN retainer, like the SP MK10/15/20/25, you could use a 70 and have no problems. If it’s in a groove around the retainer out-bound of the threads, maybe there’s more possibility for extrusion and a 90 would be better. I try to use 90s any place where there’s a HP seal involved, but I wouldn’t sweat it. It’s not going to make anything loosen up. Typically it’s the other way around; the retainer breaks loose and then the o-ring, regardless of it’s duro rating, extrudes and pops out.
If you are using a 70 duro, I would expect it to come loose over time, no question. That's a high-pressure connection. Only 90 duro o-rings should be used in HP applications.
The 70 gets squished if you're torquing it to the required 150-inch lbs for the DIN retainer.
The housing should be torqued to 220-225 inch lbs. The difference with a proper 90 duro o-ring keeps the retainer from loosening.
There is absolutely no reason to use a thread locker if you use the right o-ring and torque it to specs.
That said, you can still loosen it if you try to turn the reg body with any pressure applied from the cylinder. Turns the body into a wrench, and with the 90 duro din o-ring in place that keeps the retainer from turning against the valve face, you will loosen it.
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