1966 Conshelf with original o-rings works perfect!

[aikiguy]

I just had a friend bring over a 1966 Conshelf 1st stage regulator, attached to a 1970 conshelf 2nd. (Shiny!)

He received it from a friend that purchased it new in 1970. It has been dived only twice in 1970 never serviced!

We decided to blow out the spiders that were living in it, and hook it up to a tank.

Amazingly enough to me it worked perfectly. Great lock up, no creep. All with 47 year old o rings and diaphragm.

I did have to tweak the 2nd stage cracking pressure a little, but that worked great too.

We all uhhed and ahhhed, then ordered a rebuild kit, (I normally have some sitting around, but was out), and will rebuild them next weekend. I can't see anyone willingly diving on 47 year old o rings...

Of course the friend doesn't want to dive vintage and will be putting an octo plus on the the bc lp hose, which made me think that it is interesting that two lp ports are plenty for most modern divers too.

Guy

 

[herman]

You need to order 42 service kits, you are way behind, they do need to be serviced every year or they will explode.

 

[Oldbear]

Can you upload a picture or two...I would love to see one?

 

[aikiguy]

Can you upload a picture or two...I would love to see one?

Sure, I will have that reg set in my hands here again this weekend.

It also had a strange strap arrangement that went around your head. I guess this kept the regulator in your mouth. It was in great condition too, although we did remove it from the reg. I can put it back on for the photo.

Guy

 

[Oldbear]

Sure, I will have that reg set in my hands here again this weekend.

It also had a strange strap arrangement that went around your head. I guess this kept the regulator in your mouth. It was in great condition too, although we did remove it from the reg. I can put it back on for the photo.

Guy

Thanks...I love learning about the past's diving history.

 

[John C. Ratliff]

I just had a friend bring over a 1966 Conshelf 1st stage regulator, attached to a 1970 conshelf 2nd. (Shiny!)

He received it from a friend that purchased it new in 1970. It has been dived only twice in 1970 never serviced!

We decided to blow out the spiders that were living in it, and hook it up to a tank.

Amazingly enough to me it worked perfectly. Great lock up, no creep. All with 47 year old o rings and diaphragm.

I did have to tweak the 2nd stage cracking pressure a little, but that worked great too.

We all uhhed and ahhhed, then ordered a rebuild kit, (I normally have some sitting around, but was out), and will rebuild them next weekend. I can't see anyone willingly diving on 47 year old o rings...

Of course the friend doesn't want to dive vintage and will be putting an octo plus on the the bc lp hose, which made me think that it is interesting that two lp ports are plenty for most modern divers too.

Guy

Guy, the only O-rings to my knowledge on this regulator are on the LP hose (both ends), and the LP and HP plugs. Everything else is sealed by the diaphragm on the first stage (this is a balanced diaphragm first stage), and the LP seat on the second stage. So rather than the rebuild kit, you probably only need four O-rings. I would also check both the diaphragm itself and the non-return exhalation mushroom valve. Hopefully, the rebuild kit will have these components too. But chances are that both are still serviceable.

Here are photos of the catalog entry, and of the performance of the Conshelf XII, which should be your regulator's performance too. That funny neck thingy is a neck strap, which we in the US Air Force used to great advantage during parascuba jumps.

SeaRat

 

[simonbeans]

Before the days of octopus usage as a general practice, we found the neck strap very useful. If or when you took the reg out of your mouth, the second stage was held just below your chin, on your chest. You knew where it was. Most had some sort of quick release, i.e., snap or chip, that was easily unfastened for buddy breathing (oh PADI horror) when necessary. The neck strap fell out of favor until recently where technical types use a bungie hose or surgical tubing type of neck strap. The Conshelf series of regs were some of the best ever produced by USD. Their balanced diaphragm 1st stage was used from 1965 to the present day. Tough to beat perfection unless you use a double hose.

 

[John C. Ratliff]

Here is an example of the Calypso's (and Conshelf--same second stage) neck strap in use. This was a dive in 1968 off Okinawa, and Steven Samo is spearfishing and bagging his fish. We are using Pararescue jump tanks, and the Conshelf regulator. He is also wearing LPUs (Underarm Life Preservers), which were standard issue for U.S.A.F. Pararescue diving ops. Note we were not using a SPG, nor an octopus regulator; those developments came later. Our tanks were equipped with a 500 psig J-valve, which was how we monitored our air. When the J-valve was pulled, it was time to surface. The tanks contain ~42 cubic feet of air each.

SeaRat

 

[Luis H]

Guy, the only O-rings to my knowledge on this regulator are on the LP hose (both ends), and the LP and HP plugs. Everything else is sealed by the diaphragm on the first stage (this is a balanced diaphragm first stage), and the LP seat on the second stage. So rather than the rebuild kit, you probably only need four O-rings. I would also check both the diaphragm itself and the non-return exhalation mushroom valve. Hopefully, the rebuild kit will have these components too. But chances are that both are still serviceable.

SeaRat

That is not the case. This is a balanced diaphragm first stage (as you mentioned) and like most regulators of this design it has a balancing chamber that seals with an O-ring and a back-up ring. Both of them need to be replaced.

I would also not re-use the original HP diaphragm. It will be heavily deform. I have reused them for some of my utility regulators, but I would not reuse a rubber HP diaphragm that is over 40 years old.

The LP diaphragm is can probably be re-used, but a new one is probably softer and more flexible.

I would also replace the exhaust valve since it is probably one of the early black rubber ones. In the late 70's they started using some yellow silicone exhaust valves. Those ones seem to last forever.

Before the days of octopus usage as a general practice, we found the neck strap very useful. If or when you took the reg out of your mouth, the second stage was held just below your chin, on your chest. You knew where it was. Most had some sort of quick release, i.e., snap or chip, that was easily unfastened for buddy breathing (oh PADI horror) when necessary. The neck strap fell out of favor until recently where technical types use a bungie hose or surgical tubing type of neck strap. The Conshelf series of regs were some of the best ever produced by USD. Their balanced diaphragm 1st stage was used from 1965 to the present day. Tough to beat perfection unless you use a double hose.

It is funny how the neck strap is now in fashion in a slightly different form. In the Caribbean, where I grew up, we used to cut them off right out of the box. We just didn't believe on wrapping anything around our neck when we were involve in any water sport.


Yes, IMO the Conshelf is one of the all times best ever regulator. The first stage shares all the same parts as the Royal Aqua Master and most Aqua Lung regulators (including the latest in the line up) still use many of the same parts.

 

[John C. Ratliff]

Luis,

Thanks, I forgot about that balancing chamber.

SeaRat