Friday, July 31, 2015

CG 45 information

Information provided by Tom M (Captain on the VDH website message forum)

Not very often do we have the opportunity to work with one of these rare regulators up close.

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Link to 1953 Scripps Institue of Oceanography on Overhauling the Aqua Lung

I had the opportunity to work on a CG-45 for the first time. Some things I noted, all threads are metric but most other dimensions are the same as the Broxton, DA Navy and DAAM and it uses all the same gaskets and diaphragms. On this one the HP nozzle fit a standard tank valve O ring seat. All Spiros I have worked on have had a slighter larger metric O ring seat. This one may have been resized in the past and re-chromed as it was like new externally. My USD body vise and body ring wrench worked perfectly fine on it.

Like early Broxtons the body has no can tab cuts outs and the can has no tabs. This complicates getting the body in correct orientation to the can as it tends to turn when tightening the body ring. If the orientation is not correct it is impossible to position the diaphragm tabs so they make even contact on both ends of the horseshoe or will not contact the horseshoe ends at all. Because the hole in the can is not centered the body must be aligned with the 2nd stage seat 180 degrees from the inhalation horn side of the can and the horseshoe ends must fall on a line through the can centerline and perpendicular to the inhalation horn. See photos CG-45, 1, 2, & 3, CG-45 (2) is correct all others are misaligned.

The horseshoe adjustment is different from a Broxton or DA Navy. The two screws have a shoulder on them (photo CG-45 (7) ) that is larger than the threads, the Broxton and DA Navy screws do not. You do not use number of turns out to make the adjustment, you screw the screws in until the shoulder bottoms on the body then turn them out only as much as needed to aligned the horseshoe hinge pin.

It has no IP adjusting screw, photo CG-45 (5). Because the size of the valve on my test bench I could not check the IP at 300 psi but on an 1800 psi tank it was 110. Considering most tanks of the time were 1800 to 2000 psi this is in the ball park.

It looks as it was designed to be assembled without any adjustments or special tools, just screw everything together and it should be right or close enough.
I will add that it is almost impossible to tighten the body retaining nut tight enough to prevent the possibility of it turning out of alignment so for anyone who would be diving one regularly it might be a good idea to make an index mark between the can and body so it can be noticed if any movement has taken place.

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