Mistral DH Reg (~1959) and modern tanks

[CT-Rich]

I just bought an Aqualung Mistral regulator from an an online auction. I realize most tanks of that vintage were LP and only running about 2,250 psi. My vintage tanks are twin 50s rated at 200 atm (~3000 psi). What can I expect performance wise? Is using a mistral at 3k going to be a problem?

 

[JamesBon92007]

I just bought an Aqualung Mistral regulator from an an online auction. I realize most tanks of that vintage were LP and only running about 2,250 psi. My vintage tanks are twin 50s rated at 200 atm (~3000 psi). What can I expect performance wise? Is using a mistral at 3k going to be a problem?

I just bought a DA Aquamaster (should be here by Friday) I'd be a little concerned about how much pressure the yoke can withstand.

 

[michael-fisch]

my Royal Mistral has DIN.
My older Mistral has a 3000psi yoke.
When I use them on my Siebe /Heinke double 8 liter tanks they don't get more than 120Bar (thats what the tanks are rated for)
When I use them on my USD Broxton Ave 1954 RENE tank they are only filled to 2150psi.
As far as my mid 60s IWKA double 7s go, there they work fine at close to 230Bar on a hot day.
Those regs can handle a lot more abuse than you give them credit for.

Michael

 

[Scuba Lawyer]

I have never heard of an older yoke giving way at 3000 psi but there has been lots of discussion about it over the years. The general consensus is "don't." As for breathing a Mistral at 3000 psi, it will be possible, just very uncomfortable. Mistrals are an upstream design so the lower the tank pressure, the easier they are to breathe. That is why you set lever height on a Mistral at 300 to 500 psi so it won't freeflow at lower tank pressures. Personally, I only use them on steel 2250 tanks or lower. My 2psi.

 

[michael-fisch]

Thats the reason why my Mistrals breath better the deeper I take them!
Thanks Scuba Lawyer

Michael

 

[James79]

@CT-Rich and @JamesBon92007 , I highly recommend going of to VDH forums and reading/searching the Classic Vintage Diving section. Oodles of good info over there... I'm rebuilding a DAAM and a RAM, and have found answers to all my questions so far over there (by searching, haven't invented a new problem... yet!)

Respectfully,

James

 

[GJC]

I know there could be problems with original yokes flexing under high pressure, causing leaks around the tank o ring, but does anyone know of one that actually broke using high pressure tanks?

And yes, Mistral will probably not breath well at higher pressure, but anybody try it at 3000?

 

[AfterDark]

@CT-Rich I have personal experience. I had a JetAir same as a Mistral just a different face. It was always used on the same pedestal type J valve. These valves have a more narrow body than most later made valves. I used the JetAir once on a 3000psi tank.
That yoke never fit that pedestal valve again, too loose. I had to use a longer thumb screw to solve the issue but that regulator and valve had been diving together for 50+ years without a problem until one dive on a 3000PSI tank.

My vote is no.

Good luck with your old new regulator. I'd go for a Cyclone 1st stage, a silicone diaphragm and the new style duckbill from VDH as well as new wagon wheel valves.

 

[GJC]

@CT-Rich I have personal experience. I had a JetAir same as a Mistral just a different face. It was always used on the same pedestal type J valve. These valves have a more narrow body than most later made valves. I used the JetAir once on a 3000psi tank.
That yoke never fit that pedestal valve again, too loose. I had to use a longer thumb screw to solve the issue but that regulator and valve had been diving together for 50+ years without a problem until one dive on a 3000PSI tank.

My vote is no.

Good luck with your old new regulator. I'd go for a Cyclone 1st stage, a silicone diaphragm and the new style duckbill from VDH as well as new wagon wheel valves.

Do you happen to remember how it breathed at 3000?

 

[Scuba Lawyer]

And yes, Mistral will probably not breath well at higher pressure, but anybody try it at 3000?

Yeah, some French guy - Cousteau I think was his name. He could be an arrogant self-promoting dweeb at times, but I always got along with him.