Question O-Rings Vs Quad Rings for Piston Seal on MK10 Clone

[happy-diver]

in between the leaflets

perhaps the upstream leaflet

Ha ha ha and here I was calling it the the top of the corner of the thingo or the bottom of the corner of the thingo
unless it was on its side

Silicone lube for Nitrox

I did something stupid and now i need help, so i know how stupid it was.. I dive Nitrox < 40% on holidays. I know its ok to use silicon up to 40% O2. Which is no problem, because the silicon us usually used on the inflator hose, which isnt exposed to high pressures. Now the stupid part: I...

scubaboard.com

 

[lexvil]

Pulled the SR1 apart, found some damage to the quad

it still sealed and operated but I have to assume that the tear on the shaft side caused some binding which lead to the huge IP swing. I tried to put another one in but I couldn’t without damage. I think they are just to hard for this application, you can’t use a bullet with the two part piston, preloading on the shaft as normal the quad just wouldn’t compress enough to get past the lip at the top of the seal area.

I put it back together with the regular seal and it’s working perfectly with normal (for Sherwood) 10 to 15 psi drop with a hard purge.

this may be the ticket on MK 5 where the bullet will let things mate up smoothly.

 

[rsingler]

Alas, the bullet was critical in my Mk5 reassembly, but I wouldn't call it smooth by any means. I pulled it apart twice and put in new quads each time, just to check and see if I sheared a leaflet...

 

[lexvil]

Because I’m a glutton for punishment I tried another quad in the SR. I managed to get it in with only a slight shearing of material due to the sharp edge on the piston shaft, there is a bullet of sorts for sherwood to protect the inside edge of the HP seal which you preload onto the shaft and insert the shaft with the two cupped spacers and a white lower spacer, I just couldn’t get the shaft past the bore sharp edge with the parts on the shaft. I inserted all of the bits into the bore and this time I reversed the cupped spacers so that they have the flat edge toward the quad.

it was not easy to get the shaft past the seal but with increasing pressure, turning and wiggling I got it in losing a hair of material to the piston sharp edge, next time I take it apart I’ll see if I can make some sort of “bullet” to ease the transition.

the good news is it works better this time, IP drop is about the same as the original seal and instant recovery on a purge.

I don’t really know what I’m hoping to prove here, at this point it’s just a conceptual exercise since I know there is some damage I don’t want to convey any big conclusion but it’s something to do while the ocean isn’t accepting visitors.

 

[L13]

Any new results with the quad o-rings?