One of the few Achilles heels of the original double hose regulators built by US Divers was its fixed first stage volcano orifice. If damaged or allowed to corrode the chances of repairing it to workable condition are slim to none. Damage to the volcano orifice prevents proper intermediate pressure adjustment and stability. While the regulators were in production this was not really an issue because spare parts were available.
Today, regulators that are good candidates for rebuild or restoration are put aside if the orifice is damaged until a suitable donor regulator with a good first stage can be found.
On US Divers two stage regulators the only significant difference between a DA Aqua Master and a Royal Aqua Master are their first stages. The DA's being a non balanced vs the balanced first stage of the Royal. In recent times many Royal Aqua Masters have been sold with DA first stages in them to the great disappointment of the buyer. DA's were far more plentiful and first stages are interchangeable between them. In the past I have had dozens of DA first stages for every one Royal first stage as available spare parts to repair customers regulators with.
A couple of years ago I was setting around beating my head on the table about the challenges I was having with sourcing new parts for the Argonaut Kraken. My mind was kind of wandering around and at one point I thought to myself.....We are already manufacturing the removable volcano orifice for the Phoenix first stage and are going to use it in the Argonaut so why not see if it's feasible to make an improved balanced first stage for the original regulators and use the same parts?
Luis and I talked it over for a bit and he put some preliminary drawings together incorporating some of the flow improvements learned from the Phoenix and Argonauts and I had 6 sample parts made.
The biggest challenge was the removable orifice. It comes from Aqua Lung flat on the bottom and the pin support would have hit the bottom of the orifice as the action cycled if we used it in the new first stage. One of the goals was to keep it looking as close to the originals from outward appearance. We could have simply increased the height of the first stage which would allow for the pin support to clear but that would cause the first stage to be much taller than the original.
Unfortunately I had already manufactured though my own sources the large quantity of volcano orifices needed for production of the Phoenix and Argonaut but they all had flat bottoms like the ones from Aqua Lung. At this point the new first stage was almost put on the shelf because I didn't want to source a secondary orifice that would only be needed for the limited number of Cyclone first stages I figured I would sell....
Ring Ring.......Ring Ring......Hey Herman, Is there any chance you can take a really small already finished part and put it on your lathe and machine out a nice cone shape on the backside? Oh and you have to be extremely careful of the other side because if it's scratched or damaged in any way we can't use it and have to toss it......... Herman says.......Well I don't think that will be a problem, send it on over and I'll see what I can do......Me, did I mention I have several hundred of them that need doin!
Always up for a challenge and being the perfectionist that he is they were all done with a minimal amount of casualties. I guess I should have called the new first stage The Herman because without his help it would still be on the launch pad of good ideas.
The photo above shows a production orifice made by a vendor but I think you get the point.
The Cyclone first stage comes as a complete unit ready to install in your DA, Royal or Voit Navy regulator. There are no permanent modifications necessary and other than adjusting your intermediate pressure very little else is necessary to get you going.
Adding the Cyclone first stage in conjunction with the HPR 2nd stage and new main diaphragm will give you regulator performance superior to any original and from the outside no one would really be the wiser. The balanced first stage uses all new production parts with great reliability and ease of maintenance.
My idea behind making it was for the diver who liked to experiment mixing old with new or for those who had a regulator with a damaged first stage who wanted to get it back in the water again.