When placing the housing (orifice) into the inlet tube in the D-series, aftermarket 2-013 o-rings would occasionally get pinched on the way in, even when well lubed.
Since it is almost a blind insertion (visible only thru the mouthpiece), you wouldn't find out that you'd shaved a bit of o-ring off until you pressurized the newly serviced reg.
So I began using Duro 90 2-013 orings to eliminate the pinch. Since it was a static o-ring, the duro didn't much matter. The harder o-ring slid past the sharp edge of the inlet tube much better, so I began using duro 90 orings around the housing routinely.
I sent a kit of poppets and o-rings to a buddy who loves the old scrotum reg as much as I do, and he came back with a novel issue - no matter what he did, the reg wouldn't seal. He sent it to me and this is what we found:
The hard duro 90 upper o-ring wouldn't drop into the inlet tube, no matter how hard you pushed.
It's supposed to seat like the photo above - completely flush. What was happening was that the hard o-ring was never quite getting around the corner of his inlet tube, which didn't make sense! That was supposed to be the problem with the softer o-rings.
Investigating the problem revealed a subtle difference in inlet tubes I hadn't appreciated before.
Some of them have the slightest of rounded edges. Perhaps that chamfer (or fillet) was introduced by Scubapro in response to just the problem I'd had with sheared soft o-rings.
The photo below shows the subtle rounding of one inlet tube, compared with the square edge of the other:
So in our case, the chamfer/fillet acted like a tiny ramp for the curve of the hard o-ring, which squeezed right back out, instead of dropping onto the flat of the o-ring land.
The solution, of course was to go back to a duro 70 o-ring for the top ring on the housing (or both, if you wish). With the usual pressure, the housing dropped right into the inlet tube, as can be confirmed by looking through the mouthpiece.
So my tip is to check your inlet tube carefully for architecture. If you have a squared off inlet, consider using duro 90 2-013 orings on the housing to avoid shearing.
If you can't get your housing to seat, check to see if your inlet is subtly chamfered, and go back to the old purple o-rings if you have them, or use duro 70 2-013's.
Since it is almost a blind insertion (visible only thru the mouthpiece), you wouldn't find out that you'd shaved a bit of o-ring off until you pressurized the newly serviced reg.
So I began using Duro 90 2-013 orings to eliminate the pinch. Since it was a static o-ring, the duro didn't much matter. The harder o-ring slid past the sharp edge of the inlet tube much better, so I began using duro 90 orings around the housing routinely.
I sent a kit of poppets and o-rings to a buddy who loves the old scrotum reg as much as I do, and he came back with a novel issue - no matter what he did, the reg wouldn't seal. He sent it to me and this is what we found:
The hard duro 90 upper o-ring wouldn't drop into the inlet tube, no matter how hard you pushed.
It's supposed to seat like the photo above - completely flush. What was happening was that the hard o-ring was never quite getting around the corner of his inlet tube, which didn't make sense! That was supposed to be the problem with the softer o-rings.
Investigating the problem revealed a subtle difference in inlet tubes I hadn't appreciated before.
Some of them have the slightest of rounded edges. Perhaps that chamfer (or fillet) was introduced by Scubapro in response to just the problem I'd had with sheared soft o-rings.
The photo below shows the subtle rounding of one inlet tube, compared with the square edge of the other:
So in our case, the chamfer/fillet acted like a tiny ramp for the curve of the hard o-ring, which squeezed right back out, instead of dropping onto the flat of the o-ring land.
The solution, of course was to go back to a duro 70 o-ring for the top ring on the housing (or both, if you wish). With the usual pressure, the housing dropped right into the inlet tube, as can be confirmed by looking through the mouthpiece.
So my tip is to check your inlet tube carefully for architecture. If you have a squared off inlet, consider using duro 90 2-013 orings on the housing to avoid shearing.
If you can't get your housing to seat, check to see if your inlet is subtly chamfered, and go back to the old purple o-rings if you have them, or use duro 70 2-013's.
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