Dumb question #92 - Oring question

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Landlocked123

Contributor
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Location
Reisterstown, MD
# of dives
200 - 499
So I have purchased a few tanks (HP 100 and HP 133 and a handful 2 bony bottles) over the years. Every time I go to change the Orings (lost or damaged/worn) I notice that the O rings my local lds gives me are somewhat softer and different looking than the ones that came with the tanks. The ones I get appear to be same size but are noticeably softer. Yesterday I got in the mail some VIton orings which I understand are made for Nitrox. They are way stiffer and seem thicker (not larger) than the ones my LDS sells me. What is the deal? Is there not a standard scuba Oring ? So should I use the larger stiffer ones ?
 
the viton orings are most likely just higher duro than the NBR duro 70 rings from your lds (which are the cheapest / most widely available orings). i only bother to replace with viton because in bulk amounts of 100+, the difference comes down to a difference of pennies.
 
Exposure to air will cause old buna o-rings to harden considerably. This won't happen with Viton.
 
they should be 214 o-rings, 90 durometer. If they feel softer, they're being lazy and buying 70 or 75 duro. Not cool. If they are different thickness, then they're giving you the wrong one entirely.
 
Ok thanks all so sounds to me cant go wrong with the Viton Orings. They just seem beefier and better quality and Nitrox ready. I am switching the ones I had replaced with the VIton ones. Got I love this board.... :)
 
Regarding the Shore,( Duro) the recommendations from my consultants is that the hardness of the o-rings are determined by the pressure and level of friction at the point of use. For applications of high pressure (over 100 bars) is recommended the use of hard o-rings (Sh 90) since they can handle pressure much better than the soft ones (Sh70) Nevertheless soft o-rings (Sh70-Sh75) are used for static applications with pressures, (over 100 bars) without recorded problems. I have wideness of a shreated soft o-ring (sh70) when it was mistakenly used on a scuba the tank valve due to high pressure and probably over tightening first stage to the tank valve, but i also have customers that prefer soft o-rings for all their applications. In respect of manufacturing is more difficult to make hard o-rings due to technical factors and thus the availability of soft o-rings in the market is much more than the hard garde.
Very soon at scuba gaskets one will be able to find a variety of Hard grade (Duro 90 -Sh90) scuba o-rings in viton and EPDM on top of the existing hard o-rings of NBR (Nitrile) and Polyurethane that we already have, that was specially developed and manufactured for scuba application.
 

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