New Mistral for the New Year

[artc]

These DW Mistrals are quicklly becoming my favorite DH regulator. They breathe great on LP tanks and are SO simple to repair and maintain. I found a nearly mint Warner with a long yoke on ebay and just finished rebuilding it. I will test dive it on Sunday. 

 IMG_0266 by Arthur Challacombe, on Flickr


IMG_0267 by Arthur Challacombe, on Flickr


IMG_0269 by Arthur Challacombe, on Flickr

[nikeajax]

Art, very fun My HW Scubair project is on hold for a while due to the extra robust monsoon season California is having, hopefully I can set something up with Phil sometime to do those extra LP-ports.

How many Mistrals do you have?

I have one Divair, two Scubas, one Scuba Deluxe, one GL, two Dacor Clippers and one Olympic first stage that Phil turned into a DH conversion that will get mated to a set of Clipper cans, oh and James made a diaphragm for it too!

JB

[artc]

Hi JB, I hope and pray the rain is not adversely effecting you and you and Phil can finish up your Scubair project soon. This is my third Mistral if I count my converted Stream Air. For DH regulators, I stick to US Divers due to parts availability and ease of maintenance. I’m looking forward to someday getting a Royal Mistral if I want a challenge.

[SeaRat]

Here is my Healthways hybrid Gold Label:

IMG_1778 by John Ratliff, on Flickr
This is one of my best-breathing single stage regulator.

Here is another view of it.
IMG_1775 by John Ratliff, on Flickr
Note it is mounted on a Scubapro two-post manifold, allowing me to also mount a single hose regulator and have a SPG/Computer, LP hose and octopus.

Here is my Mistral on that same manifold.
fullsizeoutput_29b5 by John Ratliff, on Flickr

Here is my Overpressure Breathing regulator (predecessor to the Mistral):
IMG_1256 by John Ratliff, on Flickr
This is probably my best-breathing regulator, with a hose-within-a-hose Venturi concept.

John

[artc]

Sweet rigs there John. How do you like the Sea4 regulator? I have one that I’ve never used. Locks up well at 135psi, but l don’t know it’s maintenance history.

[vance]

I've bought, rebuilt, and sold 30+ Mistrals over the past 10 years. They are one of two really great single stage regulators. The other is the Scuba GL. The GL might even be the better performer, but it is fussier adjustment-wise to get there. I've possibly had as many GLs as Mistrals.

I still have one GL, but I just sold my last Mistral (StreamAir conversion). I don't know if I'll ever buy another, but they are really worth a spot in the collection.

You are correct in saying they are easy to work on, and require few replacement parts. Once you have a silicone diaphragm, duckbill, and hoseloop, your Mistral will outlast you.

As far as hard parts go, the Mistral lever system can be reproduced with sheet of stainless steel, a vise, a hammer, and some small files!

[artc]

Hi Phil. It was your kindness in making me a Mistral lever that got one of my Mistrals up and running. I have since learned to make them in my shop thanks to your encouragement.

[SeaRat]

Jan 13, 2023 18:37:21 GMT -8 artc said:

Sweet rigs there John. How do you like the Sea4 regulator? I have one that I’ve never used. Locks up well at 135psi, but l don’t know it’s maintenance history.

The USD SEA4 regulator is a sweet breathing machine. It is wonderful! I also like the orientation of the first stage. It provides all the LP ports I need, is streamlined, and the second stage is basically a Conshelf in plastic. It seems almost indestructible too, as there does have not the corrosion problems of the brass second stages.

By the way, here is a photo of me in Alexander Springs, Ocala National Forest, Florida in 1970 with my first Mistral:

John Photos003 by John Ratliff, on Flickr

John

[antique diver]

Art, that's one fine looking Mistral! I hope you have a great day of diving with it.

[artc]

Thanks Bill. I already two Mistrals, but when I saw the pristine condition of this one I couldn’t resist.

[Tusker]

That's one of the nicest Mistrals I've seen lately Art, I'm glad you ended up with it.

Out of curiosity for those who have used both, how do you find it compares to the GL? I've got most of the parts to rebuild mine (save the O-rings — which, by the way, if anyone knows the size and hardness rating of I'd greatly appreciate it) and hope to dive it in the summer.

Jacob

P.S. I've not forgotten the very helpful information you gave me for the Calypso O-rings, Art. That project has just been sidetracked by another as I will write up in a different thread

[vance]

Jan 15, 2023 10:12:22 GMT -8 Tusker said:

That's one of the nicest Mistrals I've seen lately Art, I'm glad you ended up with it.

Out of curiosity for those who have used both, how do you find it compares to the GL? I've got most of the parts to rebuild mine (save the O-rings — which, by the way, if anyone knows the size and hardness rating of I'd greatly appreciate it) and hope to dive it in the summer.

Jacob

P.S. I've not forgotten the very helpful information you gave me for the Calypso O-rings, Art. That project has just been sidetracked by another as I will write up in a different thread

Do you have a Mistral or a GL?

I have always maintained that the GL is slightly superior to the Mistral (both using a USD hoseloop), given it is adjusted properly. This is very fussy. Both are excellent breathers, but the Mistral is easier to adjust.

The GL doesn't have a Mistral-like o'ring at the top of the valve. The only o'rings in the GL are around the hard seat, and as a spacer in the sintered filter stack, under the reserve fitting, if I remember correctly. These o'rings don't require a specific hardness. Just get some that fit.

[Tusker]

Jan 15, 2023 17:30:00 GMT -8 vance said:

Do you have a Mistral or a GL?

I have always maintained that the GL is slightly superior to the Mistral (both using a USD hoseloop), given it is adjusted properly. This is very fussy. Both are excellent breathers, but the Mistral is easier to adjust.

The GL doesn't have a Mistral-like o'ring at the top of the valve. The only o'rings in the GL are around the hard seat, and as a spacer in the sintered filter stack, under the reserve fitting, if I remember correctly. These o'rings don't require a specific hardness. Just get some that fit.

I've got a Gold Label and all the nice new silicon parts it needs. I was planning on using my current hose set until I can get ahold of another one in black for it. I've taken it apart and laid all of the parts out in comparison to a schematic, I just didn't have the right O-rings to replace the old — probably a good excuse to get a sizing cone. I know I could buy a set from TSM, but I need to buy more O-rings anyway and may as well end up with a lifetime supply. 

Jacob

[herman]

I have an exploded view of the GL in pdf if you want it - think you still have my email. For some reason, I think the oring is a 907, not sure but easy enough to measure. In any case, it should be a 90 durometer since it is across high pressure (basically 3k to atmosphere with a full tank). As a general rule, the more pressure differential across an oring, the harder (larger durometer number) it should be. Although different materials and durometers are used, burna-n in 70 and 90 are common in scuba equipment. I most likely have a big bag of them if you don't want to buy a bunch

[vance]

I have measured the dynamic pressure of a single stage valve in operation. It isn't IP, but is a similar effect compared to a 2 stage regulator, as I understand things. It is under 200 psig, so the o'ring in the Mistral valve should not be subjected to anywhere near high tank pressure. Please correct me if I'm wrong about this!