Change PU oring for buna or viton

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Diverspoint

Contributor
Messages
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Location
Puerto Morelos Mexico
# of dives
2500 - 4999
As in the header, is it a good idea to exchange a PU oring for a Buna or Viton oring?

I have a SP MK18 that needs the 01-050-162 (nr 42 on the schematics), but I do not have the PU orings at hand.

It is a 2-017 size.

Thanks in advance,

Johan
 
Turrent?
PU is very durable. Unless it shows signs of wear/damage I doubt you need to change it. If you do it's not a high pressure seal so 70 or 90 duro will work. I've had complete success with a 70 duro buna.

I've gone the other way for the piston O-ring and started using PU for that. It's a high pressure seal. SP specifies a 90 duro.
 
@fmerkel,

yup, the turret oring. It is leaking now, so maybe there was more abrasion then I thought.

I would use a PU if I had one right now, but I have run out.
 
There is not much pressure differential on that o-ring, and even though it is a dynamic o-ring it doesn't see much movement. Any duro from 70 to 90 will be fine. I like EPDM or Viton as the shelf life is longer than Buna. That is also the same size as a MK10 piston head so I use the same seal (EP85) for both applications. I don't care for PU. Low shelf life and they get crispy all at once.

I think I have a MK18/16 kit or perhaps a couple of partials I can cobble together-I'll even throw in a few free -017s :) If you're interested PM me.
 
I don't care for PU. Low shelf life and they get crispy all at once.

Would you expand on that a bit. Are there specific environmental conditions that promote the problem? I keep mine separate and in a small plastic bag.
If just 'time', what kind of time frame? I bought some for SP HP pistons seals as I was having a nibbling problem, and honking (MK20). PU seems to have helped.

Followup - looked it up, seems to be ~ 5 years for PU, 15 for BUNA, and unlimited for Viton.

Note - I'm also using EPDM in one of my turrets, maybe that MK20. It's the only thing I had in that size when I needed it.
 
The shelf life of PU (depending on what reference you use) is only about 5 years.
O-Ring Shelf Life | Global O-Ring and Seal

I bought a batch of -010 PU and before I could use even one they dried up and crumbled like Cheerios. I know, I could have just been unlucky, but why not purchase seals with longer shelf life? I have seen some PU seals installed in SP regs that were still in fair shape after 10 years, on the other hand, I have seen a lot of MK10s with PU piston head and stem seals that turn hard and crumble.

FWIW: Halocline and AWAP have had good luck with PU-so sometimes it's the luck of the draw.

FWIW #2: I don't think any of the newer SP kits have PU seals in them.
 
FWIW: Halocline and AWAP have had good luck with PU-so sometimes it's the luck of the draw.

I also got some crisp ones and I don't use them anymore. They are nice in the HP o-ring spot for MK10s, because they extrude less and IP does not rise as much in really full tanks. But EPDM duro 90s work almost as well and last forever.
 
https://www.shearwater.com/products/teric/

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