Unusual Find in an MR12
Posted: Sat Oct 20, 2012 12:49 pm
After having serviced nearly a hundred Voit/Swimaster MR12 reglators, I thought that I had pretty much "seen it all". Yesterday, I disassembled a 1979-1980 era Swimaster MR12 with a first stage containing 3 LP ports. That, in of itself, is rather unusual as the MR12 II was far more common in that time period.
Anyway, every MR12 that I had serviced utilized a high pressure balance chamber that contained an O-ring and washer that had been roll crimped in place. As has been discussed in the past, the O-ring is somewhat difficult to replace. The nylon back-up washer even more so.
The first thing I noticed was when I removed the poppet pin and button. The pin typically contained a "head" in the same manner as the USD Conshelf. This particular example was a straight shaft without the head. The button was different as well, and looks identical to a modern Mares MR12 version. Next, I removed the HP housing, and disassembled it. The HP balance chamber was plated, and had a different contour. Rather than being roll crimped, the open end was created with an interior shelf. This design was of the same configuration as that of the modern Mares and AL balance chambers. In short, the O-ring and corresponding back-up ring are easily replaced.
Luis has modified an AL balance chamber to operate in the Voit units. That modification makes replacement of the interior parts much easier.
This was apparently a very late production change. I am guessing it might even have been a Mares design back when AMF was transfering reg production to Italy. Anyway, it adds a bit more history to the MR12 development.
Anyway, every MR12 that I had serviced utilized a high pressure balance chamber that contained an O-ring and washer that had been roll crimped in place. As has been discussed in the past, the O-ring is somewhat difficult to replace. The nylon back-up washer even more so.
The first thing I noticed was when I removed the poppet pin and button. The pin typically contained a "head" in the same manner as the USD Conshelf. This particular example was a straight shaft without the head. The button was different as well, and looks identical to a modern Mares MR12 version. Next, I removed the HP housing, and disassembled it. The HP balance chamber was plated, and had a different contour. Rather than being roll crimped, the open end was created with an interior shelf. This design was of the same configuration as that of the modern Mares and AL balance chambers. In short, the O-ring and corresponding back-up ring are easily replaced.
Luis has modified an AL balance chamber to operate in the Voit units. That modification makes replacement of the interior parts much easier.
This was apparently a very late production change. I am guessing it might even have been a Mares design back when AMF was transfering reg production to Italy. Anyway, it adds a bit more history to the MR12 development.