The first double hose?

[simonbeans]

The differences between the upstream Mistral, et. al., and the Voit 50 Fathom have been discussed on Vintage Scuba - Vintage Scuba Gear at Vintage Double Hose, the forum for double hose enthusiasts.

Here is the link:
Vintage Double Hose • View topic - Voit 50 Fathom

 

[captain]

US Divers and Voit had a symbiotic relationship for a while. USD made the hard parts for Voit and Voit made the rubber parts for USD. For that reason the early USD and Voit regulators are mechanically identical. That ended when AMF bought Voit and began engineering it own regulators.

 

[John C. Ratliff]

It is interesting how the third tank in the patent drawing is illustrated/plumbed for a reserve. You have to wonder how many conversations took place over modifying a pressure gauge the diver could check but rejected due to production costs. There were certainly enough options to connect one in all the hard piping, but maybe HP hose availability or reliability was the limiting factor???

If you look at the diagram, yes there is the third cylinder for reserve. The Cousteau-Gagnan patent actually directly addresses the potential for a gauge, and rejects it:

...Referring to Figs. 1, 2 and 3, A and B are two cylinders containing compressed breathing gas. On the cylinder A is mounted a cock J through which the compressed air is admitted to the two cylinders for the purpose of filling them. The air inhaled by the diver is withdrawn from the cylinders through a common pipe N. A third cylinder C serves as a reserve; the gas contained in it being available for the diver when he feels that the supply of gas contained in the two cylinders A and B is close to being exhausted. The capacity of this third cylinder is sufficiently large to supply sufficient air to the diver to enable him to rise to the surface sufficiently slowly. The diver can thus dispense with any instruments for measuring the pressure in the two cylinders A and B. The air is withdrawn from the reserve cylinder C through a pipe O. Pipes N and O are provided with cocks K and L, respectively, which are operated by the diver. While two cylinders A and B have been shown for the normal supply of air to the diver, only one could be utilized instead...

...For the operation of the unit the three cylinders A, B and C are first filled with compressed air, the cocks K and L being closed. Before sinking, the diver, who wears about him all the apparatus, opens cock K, cock L remaining shut. Under tthe inspirations of the diver, the valve member 10 of the low pressure regulator E opens by an amount just necessary for the breathing. When the diver feels that his normal supply of air is on the point of being exhausted, he opens the cock L and slowly rises to the surface. (emphasis added]

I think the gauge was rejected due to reliability problems rather than cost; this was the mid-1940s. But that is more conjecture on my part than any documentation. I do know that Cousteau continued to be gauge-less for his divers into the late 1960s. I don't think there is a photo of Cousteau using a scuba with a gauge--at least I haven't seen one.

SeaRat