Oring Size Sherwood Bllizard and Max First stages ports 20 years old

[joseph kaffl]

Need to confirm the o-ring size for the port plugs on 20 year old Sherwood Blizzard amd Maximus first stages. I have been rebuilding regs for 30 years so not new to this. My guess is that the LP are 011 and HP are 012 but new to confirm this since their are exceptions to this, i.e. 0ld Scuba Pro MK takes an 010 LP and 011 HP. Do not have access to a factory rebuild kit to get a measurement.

 

[Couv]

Sherwood incorporates the o-ring size into the part number. Hopefully this attachment will help.

 

[joseph kaffl]

Sherwood incorporates the o-ring size into the part number. Hopefully this attachment will help.

Thanks just what I was looking for

 

[tursiops]

Sherwood incorporates the o-ring size into the part number. Hopefully this attachment will help.

18 . . . . . . . . . .G904A . . . . . . . . .O-ring (for H.P. Port Plug)​

So what size is this o-ring?

 

[Couv]

18 . . . . . . . . . .G904A . . . . . . . . .O-ring (for H.P. Port Plug)​

So what size is this o-ring?

Probably a 904, but I would bet a -012 would work fine.
As mentioned by the op, reg manufactures disagree on some sizes that should be standardized. For instance, Scubapro will use a -010 on a 3/8" plug (typical low pressure port) where most other manufactures use a -011. Similarity, SP uses a -011 on a 7/16" (high pressure) fitting where other manufactures use a -012.

 

[joseph kaffl]

I agree, 012 seem to work fine, as I break down the regs I am finding a range of LP 010 and HP 011 s well as LP 011 and HP 012. I found the the oldest stage, a bllizard leaked with LP 010 and is fine with 011 where as the Max and the other Blizzard were okay with LP 010..................Now that I have the correct info will be going with LP 011 and HP 012 on all of them.

 

[rsingler]

It's often a function of port plug design, since many plugs get substituted in from other than OEM sources.

Since the seal is made between the side of the port and the top of the plug, those plugs that have a little hint of cone shape to the land under the head help nudge a 2-010 into the crack between port and plug top. Those that don't sometimes allow the smaller OD of the 2-010 to sit shy of the land, and the plug will leak until you start to unscrew it under pressure, and the speed of gas escape pops the oring into the gap. But then when you screw it back down, you risk pinching the 010.
In contrast, an 011 almost always fits, except for those reg bodies that have completely vertical port lands, where the reverse sometimes happens: you shear the larger 011 against the wall as you thread the port.
In the end, it's really, "whatever works, works."