Vintage Double Hose

They should have called it an asymmetrical semi-balanced regulator. It's a cool reg, but man what a Rube Goldberg way to attempt to achieve a balanced single stage reg. I truly enjoy watching the show gentlemen and cannot wait for the next chapter of the RM saga to unfold. Hell, this is almost as good as Game of Thrones.

If we made a volcano orifice in the style of the spiro royal and used an AL seat, would we need a longer main spring also or make the volcano orifice deeper to compensate and just use a longer pin?

The balance chamber looks to be most definitely an 005 oring. 006 has to big an ID and I dont see a metric one that is close. The 005 fits well with no slop.

My rubber came out real easy and its not very deep either. These pieces had to be throw aways.

Does anyone have the repair guide for these? None of my guides have the RM in them. It would be nice to see if there were any recommendations on how to run this thing.

kworkman wrote:If we made a volcano orifice in the style of the spiro royal and used an AL seat, would we need a longer main spring also or make the volcano orifice deeper to compensate and just use a longer pin?

This breaks into the realm of legitimate engineering. I defer to experts like Luis, Dave, and Herman for stuff like this.

kworkman wrote:The balance chamber looks to be most definitely an 005 oring. 006 has to big an ID and I dont see a metric one that is close. The 005 fits well with no slop.

I agree but if you mic the stem on the hard seat it is way too small to properly seal in a 005. I forget the numbers off hand but at least the one I have is way too small to work properly, esp after a little wear sets in.

My stem measured .1025 and the 005 oring is .1094. The closest metric I could find is 2.2mm and the stem is 2.6mm

Hi everyone, I was looking for some information about the USD Royal Mistral to write a post in my blog when I bumped into this long thread.
I have rebuilt mine, tuned it and dove it. The secret of getting the seal was to glue the soft seat (as Luis said) . The regulator breathes well until you inhale a bit too strongly, the venturi effect kicks in and the air flow becomes a blast...
I will write a full post about the restoration of my royal mistral, in the meantime you can have a look at the video to see the blast effect... the first time it is surprising ... to say the least!

https://youtu.be/8RrZTeqD5YY

Happy to have any comments on this "blast effect"

Cheers!!

Stephane

stefeyme wrote: ↑

Sat Aug 11, 2018 11:59 am

Hi everyone, I was looking for some information about the USD Royal Mistral to write a post in my blog when I bumped into this long thread.
I have rebuilt mine, tuned it and dove it. The secret of getting the seal was to glue the soft seat (as Luis said) .

Stephane,

Can you describe how you glued and what glue you used please for the soft seat?

Hi Ron, sure,

I used Loctite Super Glue-3. The same I use to hold DAAM second stage screw nut.

Clean the retainer and the disc, make sure no there is no silicon grease - I used a bit of acetone for that.

Put some glue (1 or 2 drops) on the retainer making sure it goes all around, place the disk in its position and press a bit on it.

I use to wait 24 hours.

It worked well for me.

I hope this helps!

Cheers

Did you cut your own material or use an o-ring? Did you save any pictures? It would be nice to share a few here for the next diver

kworkman wrote: ↑

Sun May 22, 2016 11:36 pm

My stem measured .1025 and the 005 oring is .1094. The closest metric I could find is 2.2mm and the stem is 2.6mm

0.1025" = 2.60 mm
0.1094" = 2.78 mm

La Spirotechnique specified the French R Standard (pre-dated ISO Metric) for o-rings on their Royal Mistral.
Its quite possible US Divers did the same on their own Royal Mistral... R1?
R0 ID 2.4 x 1.9mm (OD 6.2)
R1 ID 2.6 x 1.9mm (OD 6.4)
R2 ID 3.4 x 1.9mm (OD 7.2)

French R Standard o -rings can be had from The O-Ring Store
https://www.theoringstore.com/index.php ... 5b7c332336
https://www.theoringstore.com/index.php ... 5b7c332336

Unfortunately R1 is only available as a 70 Duro hardness, could extrude and 'nibble' under full tank pressure... R1 90 Duro may be available from French suppliers?