Can you identify this first stage?

[chewie]

Hi All, I just recently acquired a R109 with a 1st stage which I assume is a mk5, but the notes of the seller said that it is a mk4, but there have been no mk4 manufactured. just want to be sure of this before reservicing the unit.

 

[Sam Miller III]

Sam and all..... I could not displace it at 500 psig, but could cause a slight leak by pulling and simultaneously twisting the gauge. When the gauge got to 50 psig, by twisting, pulling and pushing at 90 degrees to the gauge yolk's alignment, I was able to release enough to get the O-ring to displace and cause depressurization. I figure that using a 3x safety factor, it would be extremely difficult to happen above 150 psig. But it can happen with some pressure and enough force applied. Chances of this occurring during a normal dive are very low, and would include exiting on a boat and getting the SPG caught in a ladder, or something like that.

SeaRat

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A panic scenario==entanglement in kelp, excessive breathing, air pressure rapidly diminishing, it did happen some time during the later portion of the dive. I would suspect that a disconnect or a leak could occur in panic/kelp/out of air situations

Recalling the trial the life guard testified that the "regulator was not attached to the tank when the body was recovered"

Very interesting the Pneumatic valve was not a SCUBA Pro development it was the brain child of a Florida dive operator who developed and sold it to Scuba Pro

SDM

 

[redacted]

Hi All, I just recently acquired a R109 with a 1st stage which I assume is a mk5, but the notes of the seller said that it is a mk4, but there have been no mk4 manufactured. just want to be sure of this before reservicing the unit. View attachment 154557

It is not a Mk5. It is an unbalanced piston - Mk2/Mk3/Mk200. They all use the same body and differ by the diameter of the piston (and the piston head o-ring). Hard to distinguish until the cap is removed.

 

[JohnB47]

I had a Mk 6 when they first came out, in the early 70's. It was beautiful and cool and worked great. Then I decided I needed double tanks, so I bought the latest and greatest (at the time) - the ScubaPro double reserve double manifold, with two J-valve levers. That also looked cool. Then I tried to mate the Mk 6 to the double manifold, and found that there was some small difference in the dimensions of the manifold, and the Mk 6 would not seat properly. I had to get it downgraded to a Mk 5 yoke in order to use my doubles. After that, I found that the double reserve double manifold was not a good idea either, because with a submersible pressure gauge (which were also the latest thing about that same time), J valves were not only unnecessary but unnecessarily confusing, since the gauge would not read the full pressure in the tank unless you pulled the J valve lever. After that, I kept the J-valves pulled down all the time, so it would have been better if they had not even been there at all.