Scubapro MK20/G250: Ten Years After

[redacted]

3 PSI creep is well within SP's specs, and a new seat is $7. No big deal either way. Shall I flip a coin?

Spoken like a man who can walk into an LDS and expect to buy parts.

I would never swap out a seat for only 3 psi of creep.

 

[Zung]

Why? Is it unlawful to initiate an exchange of money against parts?

 

[Texfrazer]

Why? Is it unlawful to initiate an exchange of money against parts?

You just love rubbing it in, don't you....:mooner:

 

[Couv]

You just love rubbing it in, don't you....:mooner:

...just what I was thinking.

Yeah, buy something else or if you do buy the seat, keep it for later. Thanks for another cool graph, Brother Zung.

 

[Zung]

I mess with the second stage some more, swapping parts with a rogue G250 I reported elsewhere, and there's a strange little incident: the #23 o-ring on the hose side of the barrel keeps extruding out of its groove when I push the barrel into the housing. It's a 01050160, or 2-016 EP70. After a couple of tries, I put a 2-015 EP70 and it works OK now.

Interestingly, awap's first o-ring sizes list stated the 160 should be a 2-015. But then I used the 2-016's in 5 others seconds and they work fine.

 

[Couv]

First off, you should know by now not to question The Master. But if you want to figure out an o-ring size and you don't have a NEW example. Take that fancy dial caliper of yours and measure the groove the o-ring fit's in. Then subtract approx. 2% (multiply by .98) then find the closest I.D. size or smaller (to as much as 5%) on a chart. http://www.marcorubber.com/sizingchart.htm For example, on your air barrel you measure the groove and find it's .555 inches. Multiply times .98 = .5439 The closest or smaller is an I.D. of .551 which is a -015

Edit: In a very roundabout way I'm trying to say an o-ring should have about of 2-5% stretch for a good fit.

I'm at work and I don't even have any of those cheap, sissy-boy, excessively o-ring laden, plastic fantastic, non-metal, POS G250ies anymore, so I'm just guessing at the figures above. However, I'd be interested to know what the dimensions really are.

Couv

 

[Zung]

I like this: whenever The Master goes against Scubapro, The Master wins!

Edit:

In the ugly world of reality, we're not there quite yet:

• At the hose end:
  • The groove has a diameter of 15.88 mm or .6252 inch
  • 2% off is .613"
  • The closest one on the chart is still a 2-016 at .614" - the 2-015 has an I.D. of .551"
• At the adjustment knob end:
  • The groove has a diameter of 16.20 mm, or .6378 inch
  • 2% off is .625"
  • OK-ish for the 2-016

I guess the hole in the housing has something to do with this as well.
For now, it works: I did the "suck test" and it's fine.

 

[Zung]

... I don't even have any of those cheap, sissy-boy, excessively o-ring laden, plastic fantastic, non-metal, POS G250ies anymore, ... Couv

Bro, you're still diving those regs made of stone?


PS:
They are dangerous and non compliant to the emission law of the state of Texas. You should send them to me immediatly for proper disposal!

 

[Couv]

I like this: whenever The Master goes against Scubapro, The Master wins!

Edit:





In the ugly world of reality, we're not there quite yet:

• At the hose end:
  • The groove has a diameter of 15.88 mm or .6252 inch
  • 2% off is .613"
  • The closest one on the chart is still a 2-016 at .614" - the 2-015 has an I.D. of .551"
• At the adjustment knob end:
  • The groove has a diameter of 16.20 mm, or .6378 inch
  • 2% off is .625"
  • OK-ish for the 2-016

I guess the hole in the housing has something to do with this as well.
For now, it works: I did the "suck test" and it's fine.

Sensei, the operative term is "or smaller." Let's work in mm
The groove you measured is 15.88mm
15.88 X .98 = 15.5624mm
The closest is a 15.60 but that is larger than 15.5624 so
We go to the next smaller a 14.00mm
Which is the same as a -015

Bro, you're still diving those regs made of stone?

Dive them? No, I just spend all my time gawping at them.

 

[Zung]

Bro, you're a Master too!
And you sure know how to make me jalous.
Like I said, please send them to me immediatly and I'll forward them to our world-class atomic waste recycling plant at no charge!