Scubapro O-ring Sizes

[Zung]

... Right of the plastic bag, and inside of it are some NOS stuff I liberated from my nephew Jim's stash by the time he worked at an LDS in the mid-nineties, so they're about 15 years old.

Left of the bag are some used stuff I removed from 2 MK10 Plus's serviced by another LDS in 2000, so they're 11 years old. I know for sure the 2 011's near the seats have about a dozen dives before we put them in storage during our baby-sitting break...

OOPS! Dyslexia hit me again! But it's pretty self explanatory: left of, and inside the bag are NOS stuff, and right of the bag are used stuff. Sorry.

 

[Couv]

Must be hell when you get old.

 

[Texfrazer]

As long as you don't remember getting old, it's not so bad!

 

[Couv]

Did you hear about the dyslexic atheist? He said, "There is no dog."

 

[jacked_72]

This may have been answered already, so I apologize if it has, but does the MK25 rebuild kit contain all the parts necessary for the MK20?

 

[jacked_72]

Answered my own question with some digging in another thread and a post from Aquamaster. Putting it here for the future.

I'll qualify the statement that they are the "same", as it really depends on the time frame in which they were made.

Scubapro has changed how they have packaged the kits since they made Mk 20 kits and the contents of the kits have also changed.

For example, the old Mk 20 kit used to include a white plastic backing o-ring for the Mk 20 piston as it used a single o-ring and a backing ring in the same groove. Over time there were 3 variants of the Mk 20 piston and the third one was eventually the same composite piston that is used on the Mk 25 - one that uses 2 o-rings and no backing ring.

So an early Mk 20 kit will have 1 o-ring and 1 backing ring, while a later Mk 20 kit will have two o-0-rings and a backing ring (to accommodate all the versions that might have been encountered), while the transitional Mk 20/25 kits will have all three as well. However the current Mk 25 kits will only have the 2 piston head o-rings.

The reason for this is that many Mk 20s have been updated with Mk 25 pistons, due to issues with the second version of the Mk 20 piston, and most techs have a stack of the white backing o-rings from kits that were not needed on pistons that did not require a backing ring.

The Mk 25 kit also contains an o-ring that goes around the top of the seat to add an additional seal as the Mk 25's adjustable seat reatiner has a tendency to leak, while that is not an issue on the Mk 20.

But generally speaking, as long as a Mk 20 kit has 2 piston head o-rings, it should work fine for a Mk 20.

 

[Zung]

Yes, the current MK25 kit contains every o-rings in the schematic, including those that are not required for annual, but it doesn't have the white wiper ring for the old all ss piston, but that wiper ring can be reused.

 

[jacked_72]

I just opened up a G250 that I recently bought. What do you suppose this oring is doing here?

 

[Zung]

Oh, I documented that somewhere: SP specified a 016 there (item #23), but space is a little tight and if you're not careful, the o-ring get partially dislodged when you reassemble the barrel.

Easy fix: remove the barrel, wiggle it a bit and re-reassemble. Alternatively, use a 015. I tried both methods, and both work.

 

[Rich Keller]

What O rings match up with the part numbers on the R108HP?

http://www.scubaproregulatormuseum.org/108_HP.JPG