Post by SeaRat on Jul 31, 2015 16:28:13 GMT -8
I went diving a while back, and performed a doff-and-don on my twin 52 tank setup. The reason was that I wanted to see where I had a leak. I had recently decided that the USD doubles manifold was better than the setup I had with two J-valves and a cross-over yolk for the doubles. Besides, that's how it came new. Anyway, I found that the center portion body, nipple and nut assembly had a slight break at the brazed (welded?) seam. So I decided to replace it with a like body from another valve I had been given. The older one had a brass on-off knob, and the newer one had a plastic knob. So I decided to clean the assembly before assembling it. I also wanted to know whether I could switch parts, and use the parts that were in better condition.
Guess what? The two valves, which look almost identical, have different innards! The bonnet (nut that holds the stem in place) on the older one has a classic right-hand thread, and the newer one has a left-handed thread. The older stem has a raised ridge that seals against a plastic (nylon, probably) washer; the newer stem has a flat piece which simply rests on what looks like a rubber washer that extends into the body, forming the seal by going around the stem above this ridge area. So the two cannot be interchanged. The retainer assembly seat disk looks the same, except the older one has a hole in the middle, and the newer one does not.
Who would have thought ("wooda' taught"--Jaybird language) that there was an upgrade in the design of these components? I surely did not. Photos at eleven.
John
Guess what? The two valves, which look almost identical, have different innards! The bonnet (nut that holds the stem in place) on the older one has a classic right-hand thread, and the newer one has a left-handed thread. The older stem has a raised ridge that seals against a plastic (nylon, probably) washer; the newer stem has a flat piece which simply rests on what looks like a rubber washer that extends into the body, forming the seal by going around the stem above this ridge area. So the two cannot be interchanged. The retainer assembly seat disk looks the same, except the older one has a hole in the middle, and the newer one does not.
Who would have thought ("wooda' taught"--Jaybird language) that there was an upgrade in the design of these components? I surely did not. Photos at eleven.
John
