Old Scubapro regulator identification

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mitrax

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I would like to know which model this old Scubapro is. It has 1 HP and 2 LP ports. Second stage has number 080752. It is possible and/or worth to repair it?

TIA for your comments.
 
I would like to know which model this old Scubapro is. It has 1 HP and 2 LP ports. Second stage has number 080752. It is possible and/or worth to repair it?

TIA for your comments.
 
I think that's an old Scubapro MK-2 R-190. A new one of these sells for $160 with the main difference being that it has 4 LP ports instead of 2. To overhaul the old one might be $15 per stage plus parts (maybe $30). But if you need a couple of extra LP ports then you would have to add another $30 for an adapter. The MK-2 is a non-balanced piston 1st stage. The R-190 is a standard down stream 2nd stage.
 
It looks like an old Mk III or Mk II with a rounded cap on the first stage and a "HP" second stage. The only thing that looks weird about it is the fact that it has the thicker newer style yoke on it. That was not found on the rounded cap model Mk II or Mk III.

(This is according to the store owner/gear tech here at the shop I work for. He's been servicing Scubapro regs since the mid 70's.)
 
Yep...the first stage is definitely an older (60's or early 70's vintage) Mk III with the newer (late 70's onward 3300 psi service pressure yoke).

The second stage is the Scubapro High Performance second stage. A standard downstream design but it is very bullet proof and breathes very nice when properly adjusted. Parts are still available and it uses the same basic diaphragm as the G250.

The first stage is problematic as it only has 2 LP ports and one HP port. the HP port also uses the same 3/8th threads as the LP ports as it predates the industry change to large threads on the HP port. It could be used on a pony bottle, however it cannot accomodate the SPEC Kit used on the newer Mk III' s so is less suitable to cold water use. You may still be able to find an upgrade kit, but his won't solve the port problems and you can find a newer Mk III on E-bay for a lot less than the cost of the parts to upgrade an older one.

The blue key is inserted underneath the purge cover to keep the demand lever depressed which keeps the seat off the orifice and prevents it from taking a set. You get much better storage life that way. A quarter also works if you lose the key.
 
Just checked your picture. First stage is a MK. 3.
 
A MK-II was a non-balanced piston. A MK-V was a balanced piston. What was a MK-III? How did it differ from a MK-II? What was the time period during which it was sold?
 
The Mk III is an unbalanced piston first stage with an incredibly low parts count which makes it very bullet proof. It has one moving part and two o-rings subject to any wear from friction. It was sold from the mid 60's until the current Mk 2 was introduced in the late 80's or early 90's.

It was initially designed and introduced in the mid 60's and was a evolutionary advance on the Mk II design that is over 40 yrs old. It has evolved in stages to the currently produced MK 2 Plus.

The Mk III yoke was upgraded to accomodate 3000 psi tanks in the 70's and the body itself was redesigned to accomodate 3 LP and 1 HP ports. These Mk III's have an end cap with more of a square profile and look very similar to the current MK 2 Plus. This second generation Mk III also incorporates much smaller holes in the ambient pressure chamber designed tohold silicone grease to prevent water from contacting the internal parts. This provided excellent thermal protection and very reliable cold water performance.

Early examples of these updated Mk III's have a smooth first stage bodies while later variants from the late 80's onward have a groove in the body to hold a SPEC (Silicone Protected Environmental Chamber) boot which was designed to minimize the loss of silicone grease from the ambient pressure chamber.

The Mk 2 was a Mk III revamped a bit to allow DIN compatibility, a 4350 psi service pressure, and to add another low presure port (for a total of 4 LP ports) but was functionally the same as the Mk III.

The Mk 2 Plus incorporated a concave high pressure seat and a piston with a rounded sealing edge to mate with the concave HP seat giving a slightly higher flow rate. The Mk 2 PLus has also replaced the use of a silicone filled ambient pressure chamber with the TIS system used on the MK 20 and Mk 25. The good news is that with the lower flow rate of the Mk 2 and Mk 2 PLus, the TIS system actually works on these regs.
 
Hello, AquaMaster. Thanks for the detailed write-up on the MK-III. I have some MK-V's and MK-VII's, but had never paid any attention to the MK-II's. You've made them sound pretty good (in a basic, simple kind of way). I'll have to try one out.
 

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