Scubapro O-ring Sizes

[HenrikBP]

I think we pretty much put this one to bed, but just wanted to confirm ...

I finished rebuilding a MK10 (finally ) and initial testing showed an IP of 120 PSI with a "-1" seat. Replaced it with a "+" seat and IP went to 127 PSI per my IP gauge. So as suspected, going from "-1" to "+" increases IP.

I'd like to get the IP up around 135 PSI (my other MK10 has an IP of 137 PSI). There is one "washer" in the reg currently - it's very thin though and looks different from another washer I've seen in my MK5: it's a black plastic film rather than the thicker clear/whitish washer I've seen before.

So I'm wondering if the thin black washer is really making much of a change in IP? If not, I'm thinking 2 of the regular clear washers should bring the IP into the range I'd like.

Henrik

 

[superstar]

Measuring the thickness of two seats I have the -I mikes out at 7mm the + is 6.8 mm so by lowering the seat by .2mm you gained 7psi. It seems to me if you shimmed the spring by .2mm you should gain another 7psi that will bring your IP to 134.

 

[superstar]

.2 mm is .006 in. so a .007 shim may get you to 137 to match your mk10.

 

[HenrikBP]

Thanks Superstar. Good thinking.

I have a "friendly" LDS that may let me roam the spare "bits" box to see if I can find some official shims. I may also take a look at what McMaster may have.

Anyone have the I.D. and O.D. of those MK10 shims by chance ...?

Henrik

 

[Zung]

I'm about to do a MK10 too, and a MK10+, and 2 MK20; it's snowing here, so it's a free weekend.

I now have a whole bunch of bits & pieces, but only 1 maintenance kit for the MK10, and I intend to save it, so I'd like to use a -013 o-ring instead of the red washer (01-070-106) to seal the HP seat; the old way.

Any advice on how to place that -013 o-ring?

It appears to be a very loose "fit" anywhere. Would it be a good idea to put the reg butts side up, put the o-ring in from above, center and fix it with a bit of grease and screw the seat/retainer on top?

Edit:
Never mind, it just drops right in and stays put when I screw the seat retainer in. Sorry, I was overthinking.

 

[redacted]

I'm about to do a MK10 too, and a MK10+, and 2 MK20; it's snowing here, so it's a free weekend.

I now have a whole bunch of bits & pieces, but only 1 maintenance kit for the MK10, and I intend to save it, so I'd like to use a -013 o-ring instead of the red washer (01-070-106) to seal the HP seat; the old way.

Any advice on how to place that -013 o-ring?

It appears to be a very loose "fit" anywhere. Would it be a good idea to put the reg butts side up, put the o-ring in from above, center and fix it with a bit of grease and screw the seat/retainer on top?

Edit:
Never mind, it just drops right in and stays put when I screw the seat retainer in. Sorry, I was overthinking.

I would not trust it to stay in place and seat correctly. I drop the lubed -013 in place and then use a socket that will just fit in to press the o-ring into the groove to seat it before I install the retainer. I tried it once without seating the o-ring and it leaked.

 

[HenrikBP]

I used a socket ... 3/8" maybe?? ... to seat the washer when I put the MK5 together. Worked like a charm. Without the socket I couldn't get a good flush set of the washer.

Henrik

 

[Zung]

Thanks Gentlemen, it looks like this is my lucky day, I opened it up for the 2nd time to check, and the ring sits really tight where it's supposed to... or where I think it's supposed to.

Just to be careful, I pressed some more with a 10mm nut socket and it wouldn't go any futher.

I'll pressurized next week and report back.

 

[cbmech2]

Which one specifically are you looking for? I have a sort of similar stash from the units I service here at the house.

 

[HenrikBP]

Which one specifically are you looking for?

CB; not sure who you're asking or which "one" you're referring to?

Henrik