Proper O-ring material for CO2 Use
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Proper O-ring material for CO2 Use
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Topic: Proper O-ring material for CO2 Use (Read 3075 times))
rr_shooter
Shooter
Posts: 48
Real Name: Paul
Proper O-ring material for CO2 Use
«
on:
September 28, 2013, 11:45:04 PM »
I'm getting ready to tear down my MM QB 78 for maintenance for the first time and want to have the proper materials on-hand. I've got all the o-ring sizes, but I'm confused about the choosing the right material, especially for the two o-rings in the CO2 tube.. I've done a lot of searching (on this site and numerous others ) and found a number of conflicting opinions. Some say EPDM, others Viton or silicone; yet others recommend urethane. Some others state Buna-n (NBR) works fine.
I've seen a couple of posts stating never to use Buna in an application where it will be exposed to CO2. But I've found a number of chemical compatibility charts that state otherwise (I've attached two – one from Apple Rubber and one from Parker). In fact, a few of them (including the one from Apple) show Buna to be superior in this application to EPDM.
I'd appreciate hearing from others who have experience in rebuilding CO2 guns. I realize there are other factors to consider, but chemical compatibility is certainly important.
Thanks in advance for your input.
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HillGSA
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Posts: 874
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Real Name: Tim
Re: Proper O-ring material for CO2 Use
«
Reply #1 on:
October 02, 2013, 04:19:06 PM »
Mil Spec Nitrile
Duro = 75D
«
Last Edit: October 02, 2013, 04:51:55 PM by HillGSA
»
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fivestar45
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Posts: 607
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Re: Proper O-ring material for CO2 Use
«
Reply #2 on:
October 03, 2013, 09:39:20 PM »
Mil-Spec Nitrile for sure..I use 75D. I doubt you'll ever have a saturation failure. The key is to be sure to buy your o rings from a reputable supplier that will give you for real Mil-Spec Nitrile.
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rr_shooter
Shooter
Posts: 48
Real Name: Paul
Re: Proper O-ring material for CO2 Use
«
Reply #3 on:
October 09, 2013, 08:11:32 AM »
Thanks for the input, guys. I will look into the Mil-spec option.
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TX 200 Mark III .22 Walnut
Diana Model 36 .177
QB-78 .22
Slavia 620 .177
TF-97 .22
B3-1 .177 (2)
Crosman 1377 (2)
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eeler1
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Posts: 1387
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Real Name: Jon
Re: Proper O-ring material for CO2 Use
«
Reply #4 on:
October 09, 2013, 03:06:54 PM »
The problem with buna and some other softer materials is that they absorb c02, and swell up like a sponge. May not matter in some locations in the gun, but an oring that changes size can create problems for you in other places. Mac1airgunshop has orings in milspec and hi durometer, and should also know which specific ones you need to rebuild that gun.
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West Sacramento, CA
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Proper O-ring material for CO2 Use