USD Royal Mistral (again)

[Ron]

Also, Bill if you have extra seats or parts I would gladly pay or swap you for some.

I will take measurements, but I am almost positive that the body is just a modified DW body. It's the only part that is satin chrome too.




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[Ron]

Luis,

the orifice sits in the sleeve, with the oring between them.

Which part is the actual sealing surface? Is it the black orifice or the HP seat on this one? I've never seen a sealing surface without any nylon or Teflon.


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[Herman]

This view does not show the sleeve or seat but I know both are there

The red spring is in the wrong place, it should be above the balance chamber.

[luis]

In the picture below, the different color center ring (making the orifice edge) should be the “soft seat”. I can’t tell from the picture, but it should be an insert and it may just be black nylon or maybe just a rubberized coating. It was probably a square edge when it was first installed






What I am puzzled: if the O-ring in the orifice seals on the inside of the sleeve then the bottom/ back face of the orifice has to seal against the bottom of the body. And there is not a lot of force pushing the back of the orifice against the body.

I don't see anything sealing the outside of the sleeve against the body. This creates a potential secondary leak path for high pressure air.

The backside doesn't look like it has any means of sealing against the body.

[Ron]

I thought the same thing. The oring was around the orifice and the orifice fits in the sleeve, but the sleeve just sits in the body. Air has to be able to work its way around the sleeve then on the outside, right?




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[luis]

Yes, air would leak, big time, if there is no seal. I don’t think they could have made such a big mistake and made it to market.

Are there any recessed O-ring groves in the body? Either on the side (gland seal type) or on the bottom (a face seal against the orifice).

Can you take some pictures showing the inside of the body?

[Bryan]

In one that I disassembled the sleeve was so tight in the bore I thought it must have been press fitted. Soaking it in various solvents loosened it up but it was still very difficult to get out.

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[Ron]

So here is a shot of the body. I swear it is a mistral that they drilled out. The black orifice does have some softer material on it, you can see it shine in the picture below. Also, the sleeve has no grooves or anything. I cannot figure out how that seals.







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[Bronze06]

I am probably way behind here and this probably has already been thought of, but what about dropping in a removable o-ringed hard orifice like in the Spirotechnique Royals and shimming the hard orifice into the seating ring? Then modify a RAM seat and crown block and to hell with the crazy cone hard seat and soft orifice.

[luis]

The Spirotechnique Mistral has too small of an orifice.

The issue we are seeing is not with the orifice and seat, but the apparent lack of sealing method on the outside of the sleeve. The sleeve is required to support the pressure thrust on the balancing chamber.

On the Conshelf’s, and the RAM’s, ( etc.) instead of a sleeve, there is a step with an edge machined into the body to support the balancing chamber. In a Phoenix, an Argonaut, the Unicorn, or a Titan, (etc.) you have the same support edge, and the replaceable volcano orifice seals directly on a O-ring landing built into the body. The body is machined with three different internal diameter bores. It is critical that they are concentric.

I am having a real hard time accepting that US Diver could have made such a blatant mistake or oversight during the design and that it wasn’t caught before it went into production. Then again, we do know that they made the Deepstar II, but that one at least worked.

Thanks for the pictures.

[luis]

So here is a shot of the body. I swear it is a mistral that they drilled out. The black orifice does have some softer material on it, you can see it shine in the picture below. Also, the sleeve has no grooves or anything. I cannot figure out how that seals.

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Yes, I figured that it is probably a black nylon insert, or similar.

Can you measure (preferably with a dial caliper):
The OD of the orifice
The ID and OD of the sleeve (and the length of the sleeve)
The ID of the body.

Thanks

[antique diver]

Also, Bill if you have extra seats or parts I would gladly pay or swap you for some.

I will take measurements, but I am almost positive that the body is just a modified DW body. It's the only part that is satin chrome too.

I will dig through my old parts stash this weekend and see what I can find. Thanks for the extra photos.

[Bryan]

Tom and I both tried various compounds of rubber and plastics in an attempt to replicate the seat. I wonder now if some other anomaly in its design was defeating us that we didn't realize?

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[antique diver]

Also, Bill if you have extra seats or parts I would gladly pay or swap you for some.

I will take measurements, but I am almost positive that the body is just a modified DW body. It's the only part that is satin chrome too.

I will dig through my old parts stash this weekend and see what I can find. Thanks for the extra photos.

I found a couple of the poppets but no orifice/seat. I can't tell if its used or just a little dinghy from years in a box o junk.
Can send to you if you need it, let me know address.

[Ron]

BT, PM inbound.

Luis, will a digital caliper work? I only own a very small amount of tools.


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