Piston shaft oring Viton Duro 90 for Mk10

[Slamfire]

I am still waiting for a couple of new hp seats to arrive and then I'll try the -017 and -010 on the piston. Right now my Mk10's are using recycled HP seats that still lock up good with no creep right after the service I gave them a few weeks ago. I want to see how the trident HP seats work out.

By now I have about a dozen dives with the new Trident HP seat and the McMaster Carr viton D90 orings in one of my Mk10's: -017 in the large piston head and turret, -010 in the body sealing against the piston stem as well as in the LP ports, and -011 in the HP ports.

The Mk10 has been working fine to depths of 160', and IP has been constant (140 psi at 3000 and 125 psi at 600 no creep). One thing that has me slightly concerned is an occasional popping sound of an o-ring sealing into place as the first stage gets pressurized. Could it be because duro 90 orings do not "flow" into seal as easily (gradually?) as other softer orings do? Should I be concerned about this? I doubt that the pops come from the piston orings. I'm thinking it more probably comes from a hose or plug oring. In any case, I'll keep on using it and I'll open it up in a few months to assess how the orings have been weathering.

The G250 with the McMaster Carr Duro 90 oring continues to perform perfectly. I still haven't attempted to remove the orifice oring.

 

[Zung]

Some of my 1st stages pop when first pressurized, occasionally, including those I serviced with original kits. I don't think there's any relationship with the nature of the o-rings. I just ignore it.

 

[Couv]

If you're talking about the first time you pressurize after a rebuild, the 'clunk' is the piston and hp seat making contact. After the piston makes initial contact, there is a groove cut into the surface of the hp seat so there is no recurring thud each time you pressurize. There might also be a bit of the hp seat taking a set in the seat retainer.