Conshelf Regs

[captain]

Any upstream first stage, which is most if not all current and past regulators, can fail shut. Possible yes, chance, about as likely as getting hit by a crashing airplane.

 

[duckbill]

I'm trying to figure this out.

In an upstream 1st stage, if the IP spring breaks then, yeah, the seat would lock shut since there is insufficient spring pressure pushing on the push pin to open the seat.

But, if the diaphragm takes a dump, the air in the IP chamber would leak into the water just as though you were drawing a breath. Through the diaphragm or through the LP hose, I don't see what the difference is or why the HP seat would shut as long as the IP spring is still working to keep the seat open.

 

[akdeepdiver]

On these model regs, U.S. Divers did have a recall for a period on them back in 1977. The recall was for the retaining clamp on the outer case of the 2nd stage. Both of these regs recieved the approprite fix that was offered by U.S. Divers. Basically, the service tech replaced the screw on the retaining clamp with a different screw.

 

[captain]

I'm trying to figure this out.

In an upstream 1st stage, if the IP spring breaks then, yeah, the seat would lock shut since there is insufficient spring pressure pushing on the push pin to open the seat.

But, if the diaphragm takes a dump, the air in the IP chamber would leak into the water just as though you were drawing a breath. Through the diaphragm or through the LP hose, I don't see what the difference is or why the HP seat would shut as long as the IP spring is still working to keep the seat open.

Even a broken spring wouldn't likely shut it off completely, the IP would be lower and inhalation more difficult but probably not impossible.

 

[JamesBon92007]

As for the reg that fails shut, you might be thinking about the Calypso. There is a thread on on the other forum where there was a discussion of a recall because the HP seat could become disloged and cause it to fail shut.

OMG! I have two of those! I hope you are mistaken. Actually, I was diving with a Calypso at the time that I heard about the failures so I'm pretty sure it was not the model that I have. But they may have stuck that same name on newer regs. I do remember there was a lot of hype and such when they came out with the new regulator. I guess it's time to look for the archives of Skin Diver Magazine.

 

[duckbill]

Even a broken spring wouldn't likely shut it off completely, the IP would be lower and inhalation more difficult but probably not impossible.

I kind of figured that would be the case. I should have worded my post differently. I wonder how many of those springs have broken while in use anyway. They're awfully stout. I'd be surprised if it has ever even happened.