Which Oceanic diaphragm 1st stage do I have?

[spoolin01]

Trying to ID this reg, and hoping to find a new HP seat. No Oceanic markings except the yoke knob, but there are a couple of externally similar Oceanic regs on eBay (they have a plain cap on the the HP side, not one with the center plug like mine). Neither of them has a model ID.

 

[spoolin01]

I see one like this ID'd on eBay as a DX3, and another from the same seller that has the plain HP end cap, but no way to know if he got the ID right. Saw another purported pic that is not the same. I'm skeptical only because I found a poppet recall notice for the Oceanic diaphragm regs with mention of the DX3, but the HP seat in mine is not one of the ubiquitous poppet types.

 

[Couv]

You might have an Oceanic CDx I'll attach a copy of the service manual. Regardless, I think the CD series all take the same seat: p/n 6490

Try NESS for a seat:
Regulator Seat - Aeris, Oceanic and others

 

[spoolin01]

I'd looked at that service manual. Mine doesn't look like that one inside. It doesn't use the mushroom poppet.

Here's a pic of the parts. Unfortunately, a few parts are still off to the side. The black piece center right is I believe the soft seat. The hard seat looks like the collet from a Dremel MotoTool (not split of course), and sits back through the metal collar at the far right.

 

[Couv]

OK, I'm stumped. Are there any more parts to the poppet, pin, etc that might help?

 

[spoolin01]

Here are the parts laid out in order. You can see that the hard orifice would wedge into the hole in the black plastic soft seat. The edge of that orifice is not sharp, and the orifice small - it doesn't appear to be meant to seal by butting against a face. When I took the reg apart, the black plastic seat was installed against the flat end of the channel in the body, over an o-ring, with the flat face of the seat facing back toward the hard orifice. When I pressurize the reg, the IP creeps quickly past 150psi, even with the diaphragm spring backed way off. To further complicate things. it appears the the channel through that black piece is slightly belled on the BACK side, for about the last 2mm or so, and that belled area looks polished, as if that's where the tapered head of the hard orifice has been wedged. That belled section is far more smooth and shiny than the rest of the channel, which appears cylindrical. I can see it in the close-up pic, but then I've seen it under better lighting. As well, I can see no sign of wear or seating at the channel edge at the flat side of the seat. That seems to suggest the seat might have at one time been installed in reverse of how I found it, but that would place the o-ring back on the upstream side of the seat, which doesn't seem to make sense.

Really grasping at straws here...

 

[spoolin01]

Is this possibly a Pre-'95 balanced diaphragm? Is that the same as the DX2? This is further complicated by the existence of two otherwise externally identical looking regs - one with that plug that sits in the middle of the HP cap, and one with just a plain HP cap. I gather there was a change to the HP seat at one point for this/these regs.

 

[Couv]

Is it possible that these three pieces

could simply be replaced by this assembly?

Pre '94/post '95 I don't know, but almost all diaphragm first stages are balanced. There haven't been too many unbalanced diaphragm first stages around for decades (maybe Poseidon.)

 

[spoolin01]

Have to give that some thought. At the moment, the orientation of the hard orifice and soft seat are reversed from the design that uses that type of poppet.

On the plus side, on a hunch I checked the Vance Harlow book, and this reg is shown on page 230. Apparently I've got the pre-95 version. The graphic of the soft seat looks a little different than the one I've got, but it's a start on understanding this reg at least. I'll have to determine if the HP seat from the service kits can be used on this reg as is, or if there was some other hardware change in '95.