M1 first stage internals into ST1 first stage body?

[Dr. Lecter]

Just curious...I love my M1s, but do wish they could be paired with the beautiful, ding-resistant SS body of my ST1. Are there any internal design differences that would prevent a reg tech from reassembling a ST1 first stage body with M1 first stage components? Would the SS reg body affect the M1's O2 rating?

 

[cbrich]

Interesting idea, I have thought it about several times over, and over in the past years. The only difference between the 1st stage regs is SS vs. brass body, and both are compatible with oxygen. The piston should be the same made of the same material both since they are the same part number. So I would think the ST1 first stage can be use with oxygen, assuming it was cleaned properly.

But I think Atomic does not rate the ST1 for oxygen use like the M1 is because the second stage air barrel is made of titanium (ST1) vs. monel (m1). Monel is compatible with high purity oxygen, and you know titanium is not.

 

[Dr. Lecter]

I'm more wondering whether one can transplant the M1 first stage components into the ST1 first stage body. Just looking at the specs and schematics for the two regs, I don't think the first stage components are identical between the two aside from body material.

For backgas regs, I doubt it would matter much if I just used ST1 first stages with M1 second stages, since they're not really going to be exposed to the higher O2 % in my deco bottles (absent a deco reg failure on ascent). But if I wanted to use M1s for my deco regs despite the seat saver feature, a SS reg body would be a nice change in case it depressurized and flooded.

 

[Atomic Aquatics]

Hello Doc! The main difference between the two, besides the alloy, is that the M1 has a monel pistion inside and the ST1 has a stainless steel piston. This is what gives the M1 a higher oxyen rating. The internal components are exactly the same aside from the monel piston. You could order a Jet Seat Upgrade kit in Monel for the ST1 and it would be just like the M1 with the stainless body. I am going to check with our senior technician to make sure performance is not affected. I don't think it will affect anything, but I am not the as big of an expert as our senior tech!

Atomic

 

[Scared Silly]

But I think Atomic does not rate the ST1 for oxygen use like the M1 is because the second stage air barrel is made of titanium (ST1) vs. monel (m1). Monel is compatible with high purity oxygen, and you know titanium is not.

The second stage inlet tube on the M1 is zirconium not monel. The same inlet tube that is on Z2. In fact the only "part" difference between a Z2 and a M1 are two parts the piston (stainless vs monel) and the swivel retainer on the first stage turret of the M1 (the Z2 does not have the swivel turret). Everything else is cosmetic. So after appropriate cleaning you can make a Z2 O2 compatible by Atomic standards just by swapping out the piston and sealing it.

 

[Dr. Lecter]

Hello Doc! The main difference between the two, besides the alloy, is that the M1 has a monel pistion inside and the ST1 has a stainless steel piston. This is what gives the M1 a higher oxyen rating. The internal components are exactly the same aside from the monel piston. You could order a Jet Seat Upgrade kit in Monel for the ST1 and it would be just like the M1 with the stainless body. I am going to check with our senior technician to make sure performance is not affected. I don't think it will affect anything, but I am not the as big of an expert as our senior tech!

Atomic

So if I wanted to have an AA dealer order DIN ST1 first stages with monel pistons rather than SS pistons, how would I do so? Both M1s and ST1s have swivel turret retainers, so are they the same part?

 

[Atomic Aquatics]

Hey Doc

You would have to order the ST1s, which will come with S.S pistons, then order Monel Jet Seat upgrade kits for them. The swivel retainers are different in that the M1 is made from brass and the ST1 is made from stainless. Thanks Doc....

Atomic Aquatics

So if I wanted to have an AA dealer order DIN ST1 first stages with monel pistons rather than SS pistons, how would I do so? Both M1s and ST1s have swivel turret retainers, so are they the same part?

 

[Dr. Lecter]

Seems like a waste of good SS pistons. Oh well. Thanks for the followup.

P.S. Since the M1 is the superduty tech-flavored reg, AA should consider offering it in a more corrosion and impact resistant/O2 friendly stainless steel first staged version. It obviously wouldn't require any new tooling and I am pretty sure I'm not the only one who'd buy them.

Being able to order them with cave rings installed as well as in pre-configured stage, doubles, and longhose/bungied backup single tank sets would just be icing on the cake. I get that all of these are things I can do to the reg after I buy it, but I am then forced to go get new hoses and left with a bunch of rather expensive AA components/hoses that I never needed or wanted.

 

[Dr. Lecter]

Hey Doc

You would have to order the ST1s, which will come with S.S pistons, then order Monel Jet Seat upgrade kits for them. The swivel retainers are different in that the M1 is made from brass and the ST1 is made from stainless. Thanks Doc....

Atomic Aquatics

I was looking at this idea again today and noticed a schematic showing that the ST1 has a different first stage main spring, 21-0570-00, than any other AA first stage, including the M1, which use 21-0574-00. What's the difference between these two springs?

It also looks like the M1 swivel retainer, 01-0012-MO, is monel instead of brass... though the ST1 and the B2 seem to use the same swivel retainer (01-0012-00).

Also, why does the M1 second stage have the same inlet tube as a Z2? Make em out of 316 stainless and charge me extra for the better corrosion resistance/harder to machine material!

 

[Tortuga68]

Nice to see some informative responses from the manufacturer, kudos