75 or 90

[broncobowsher]

Tank neck O-ring. I know the size is a 214. Viton for some O2 compatibility. But I can't find a consensus on if it should be the soft or the hard O-ring. My local shop just has a drawer with the O-rings but don't know what they use. I think I am using the 90s. They feel pretty stiff. Not much of a real test.

Is there a guide to which one to use when? I'm guessing the 90 gets used most of the time with the square cut gland and the bevel cut tanks (old steel 72s) take the 75 for better conformability?

Figure it is better to ask the question before ordering up a box of them.

 

[tbone1004]

@herman will yell at me, but it's considered a static o-ring *yes I know it's dynamic when it is installed*. Static o-ring on the HP side means 90duro. They'll still hold in the bevel cut tanks, I have them in all of mine.

They're not expensive on Amazon

 

[Scubagaskets]

Tank neck O-ring. I know the size is a 214. Viton for some O2 compatibility. But I can't find a consensus on if it should be the soft or the hard O-ring. My local shop just has a drawer with the O-rings but don't know what they use. I think I am using the 90s. They feel pretty stiff. Not much of a real test.

Is there a guide to which one to use when? I'm guessing the 90 gets used most of the time with the square cut gland and the bevel cut tanks (old steel 72s) take the 75 for better conformability?

Figure it is better to ask the question before ordering up a box of them.

Yes for high pressure applications (over 100 bar) the sh90 or duro 90 is preferable to be used since they can tolerate pressure better than sh70 -sh75 . Nevertheless for the tank neck o-ring static application it was proven that the sh 70-75 works ok since many of our customers prefer to use soft o-rings for this application for their own reasons.
You searched for 214 - Premium O-rings Provider for Scuba Diving

 

[herman]

Yea tbone you should know better.
The bottom line is at higher differential pressures the oring durometer needs to be harder to help avoid extrusion. Softer ones may work but the tolerances between the parts have to be closer to get away with the softer material.

 

[broncobowsher]

OK, a batch of 90s has been ordered.