Tell me about R-valves

[roakey]

As far as I can figure out from the web and the 1962 diver's manual loaned to me by my local dive shop, they were J-valve-like, but instead of any moving parts, they simply had a restriction that choked off the air at a low pressure so breathing became hard.

But then things seem to diverge...

Some places say you could reach back to the knob, turn it and get the rest of your air like a J valve, others imply that you just had to ascend, and as the air viscosity dropped with ambient pressure, you could breathe on the way up.

Anyone have any experience with this kind of valve, and if so tell me about it!

Roak

 

[dlegros]

I found this on http://www.sandiasnorkel.com/history/his-f_dk.htm

"R" valves; The positive or automatic reserve valve differs from the constant "J" reserve in that when the reserve is in effect, the diver must rise in the water to get sufficient air to be comfortable. That is unless he reaches over his shoulder and completely opens the valve to "fill position." This was a difficult maneuver, and the valve did not survive

But there is not a lot of info out there.

Dom

 

[Otter]

The Sandia site talks about a "fill" position, but the picture seems to only show a Open and Closed position. Presumably, Open is not the same as Fill as there seems to be a need for an intermediate position.....open for fill, open for use (with reserve), and completely closed.

 

[DA Aquamaster]

Scubapro used to sell a modified J valve called a DCAR (Depth Compensating Automatic Reserve) Valve.

A standard J uses a fixed amount of spring pressure acting on a seat to determine the reserve PSI. The DCAR valve used ambient pressure to augment the pressure on the seat and to in effect increase the PSI held in reserve. The deeper you were, the larger your reserve. This sounds mechanically similar to the R valve as described.

 

[pescador775]

The R Valve was Ref letter 'R' in the 1955 USD catalog. USD called it the 'positive reserve valve'. This low priced valve was produced for those who could not afford the $30 price tag for the 'J' constant reserve. The valve itself was a post design made of nickel/brass and very similar to the 'K' valve in appearance. At the orifice, there were two holes drilled to deliver or receive air, a small hole below and larger hole above. The distinct knurled round knob of the R valve sat atop the post and controlled the position of the hp seat. Turning the knob a half turn exposed the bottom, small orifice. Turning the knob full open would expose the large hole as well. Underwater, with the knob half open exposing the small orifice only, the diver would experience restricted breathing at about 300 psi and would ascend slowly whereupon, in accordance with physics, more air would be delivered as the diver rose. If a situation occurred where he needed reserve air immediately before ascending he could reach over and back and turn the knob full open exposing the large orifice.

When filling the tank USD required that the knob be in full open position.

A similar reserve feature was built into the Divair and SCUBA 2 hose regulators. However, the SCUBA could not be triggered to release air at depth. The diver HAD to ascend to receive reserve air.

 

[roakey]

Thanks for the help, folks. Turns out that the picture I posted is not an R valve, but a flavor of J valve that required you to reach over your head and twist the knob in order to release the reserve. It didn't last long (rightfully so ).

I did track down a fuzzy picture of a real R valve at:

http://www.goingunder.net/VGFS4.htm

It's similar to the one in my picture, it just has three positions instead of two.

Again, thanks for filling in a pice of diving history I didn't know about!

Roak

 

[mrducks]

all valve pics in this thread are tapered npt....not used any longer in scuba (steel industrial and medical bottles still use npt)
modern day scuba uses 3/4 and 5/8 o-ring sealed tank valves.
valves with reserves and gauges belong in nick icorn's museum.