Working on a CG 45

[Bryan]

Information and pictures by Captain (Tom Madere)

Bryan, you might like to post this somewhere on the site once the new forum gets lined out.


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.

[captain]

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.

[Bronze06]

Great photos and write up Captain!!

[ovalis]

Interesting observation on where the demand lever lines up in relation to the tabs on the diaphragm. I've never really thought about that before. All the Broxtons, Navy Type, & blue labeled Navy Approved have the 2nd stage orifice placed 180 degrees from the intake horn as is normal, but almost all but one of the orange labeled Navy Approved regs that I've seen have the 2nd stage orifice lined up in front of the intake horn just like all the AM's & RAM's. I'm curious to go open one up now and see what the deal is.

[captain]

Interesting observation on where the demand lever lines up in relation to the tabs on the diaphragm. I've never really thought about that before. All the Broxtons, Navy Type, & blue labeled Navy Approved have the 2nd stage orifice placed 180 degrees from the intake horn as is normal, but almost all but one of the orange labeled Navy Approved regs that I've seen have the 2nd stage orifice lined up in front of the intake horn just like all the AM's & RAM's. I'm curious to go open one up now and see what the deal is.

You probably have DA Navy that was manufactured at the time (1958)of the transition to the Aqua Master. The 1958 catalog lists both the DA and the Aquamaster. Plus it had the reputation of being used by the Navy, It would be another year or so before the Navy accepted the Aqua Master into service. I have one also and it has an unfinished hookah port like the non mags do. My best guess is the new Aqua Master body was in production but USD still had DA Navy parts in the system and rather than let them go to waste they just continued to use them up making DA Navy's using new Aqua Master bodies.

[ovalis]

Yes, 1958 was a transitional year over at USD. I've been tracking USD serial #'s for the past 10 years along with all the changes that were made to pinpoint the years produced corresponding to the serial #. With regards to the "Navy Approved", there has been speculation to the blue label & orange label, when, why, etc. I don't have the numbers in front of me at the moment, but they made a lot more blue labels than orange labels. All the blue labels that I tracked had the 2nd stage pointed 180 degrees away from the intake horn, and all the orange labels with the exception of one had the 2nd stage pointed at the intake horn like the Aquamaster's & RAM's. So my guess to the difference in labels is that the blue label was produced in 1957. When the Aquamaster was released the following year in 1958, it obviously had a blue label, so my guess is that USD changed the Navy Approved to the orange label to differentiate it from the Aquamaster. Makes sense to me since they also rotated the 2nd stage around to match the Aquamaster too. This is where it peaks my interest in this thread regarding the lining up of the demand lever to the diaphragm for the orange label Navy Approved. We all know about the frugalness of USD leaving no waste, using up inventory where ever they can. But I think the opposite happened regarding the Navy Approved bodies they had in stock. I think they continued to produce the Navy Approved because the Navy wanted them, but when the Aquamaster was first released in 1958, they too were made with the Navy Approved bodies and did not have a hookah port (not even the stubbed version) on them either. It was about 3-6 months later that the Aquamaster was released with the new body featuring the hookah port, thus leading to the Navy version body that you have with the stubbed unmachined hookah port.

[Bryan]

Rob diving the CG45 discussed above in Whitestar Quarry last week

[ovalis]

So Rob, give us a product review, how was it diving the good old CG45?

[1969ivan1]

I would say that it actually breathed really well. As there are no one way valves or wagon wheels in the mouthpiece I did have to do a roll now and then to clear the mouthpiece. The rubber mouthpiece was a little hard, but owing to its originality I did not want to replace it for the dive. I took it to a depth of about 25 feet (the thermocline). Eventually the reg started to breathe wet and I had to abort the dive as the diaphragm had slipped. The failure was my fault as I had put a band clamp on the cans and really failed to make sure the clamp was holding the cans tightly. A simple squeeze of the clamp in a vise or going back to the orig clips should solve this problem for future dives.
It was a real treat to dive this reg and while I know there are a lot of collectors that may have a cg45, not too many can say that they have dived theirs. I would like to take it for spin again this Saturday. Perhaps I can depend on George or Greg for some more photos and or video.

[ovalis]

Which diaphragm were you using, a new silicone one? Those early gum rubber ones are usually always dry as toast.

[eskimo3883]

Hi,

I believe the body retaining nut in the CG45 is a bit different size than that on USD regs. Did you use a USD body retaining nut wrench or did you mod one to supply a better fit?

[captain]

My USD body nut wrench worked fine. The only significant difference I found is the spring pocket spacing on the body is slightly narrower and it wasn't a completely perfect fit on my body fixture I use to tighten the first stage into the body. I have seen a couple of slightly different designs of the USD wrench, it may be possible one works better than the other.

[Bronze06]

WOW, the more I look at this post the more I stand in awe of Emile Gagnon. Not to say J.Y. Cousteau didn't play a major role, but the design genius behind everything we dive today goes to Gagnon. For a device that (to us now with the benefit of hindsight) appears relatively simple and follows the K.I.S.S. rule, the man was absolutely brilliant. Many of us have seen pictures of Cousteau and Dumas diving with La Prier equipment in photos from the late 1930s. La Prier's constant flow reg was considered revolutionary for its time and was controlled by a hand valve. The British, Germans and Americans were working on various rebreather tech and variations of the La Prier theme for twenty years before Gagnon entered the fray. We really don't give enough credit to old Emile for the impact he made on diving. With out his design, I am sure that we would not have seen something similar until the mid 1950s if at all. Not bad for a French Canadian mechanical engineer.