AquaMaster Hookah to LP port adapter

[ew1usnr]

The old AquaLungs do not have LP (or HP) ports. So, you can't add an octopus or an inflator. The AquaMasters (DA and Royal) do have a hookah port, however. The hookah fitting allowed the regulator to be hooked up to a surface-supply air hose. The threads on this port are the same as for an oxygen regulator. I visited an industrial hose shop and explained that I wanted to reduce the hookah fitting to a LP port. The attached picture shows the result. The chrome nut is the original hookah port cover. The adapter has DIN style captured o-rings on both ends. I was going to screw a three-port swivel adapter into this (for separate inflator and octopus hoses), but the assemble was so long that it looked like it would break if it were hit against somthing. So, I instead screwed in a single hose inflator integrated octopus (like a Sherwood Shadow) and routed the hose under the regulator to the left. I replace the original short hose with a longer octopus hose to make up for the hose length lost in the curved routing. The rig looks good and works. I hear no air leaks and can now dive my old double hose with an inflator and octopus. A Dacor valve with HP port will allow me to add a pressure gauge and my AquaLung will then be provided with all the modern conveniences.

[ew1usnr]

Here is a shot showing what it looks like with the adapter in place and rigged with an octo/inflator:

Another advantage of this arrangement is that you can snap an intermediate pressure (IP) gauge into the inflator hose. It makes it easy to fine tune the regulator. The manual says 110 psi IP for the DA AquaMaster and 100 psi IP for the Royal. This is on a 2200 psi tank pressure.

[ScoobieDooo]

Very nice ew1usnr...

[ew1usnr]

ew1usnr once bubbled...
... you can snap an intermediate pressure (IP) gauge into the inflator hose. It makes it easy to fine tune the regulator. The manual says 110 psi IP for the DA AquaMaster and 100 psi IP for the Royal. This is on a 2200 psi tank pressure.

Let me add some detail on this.
A Royal AquaMaster has a balanced first stage. The IP should remain constant regardless of tank pressure. The DA has a non-balanced diaphragm first stage and the IP will vary considerably between high and low tank pressures. The IP will DROP as tank pressure goes up. That is another reason why not to use these old regulators on 3000 psi tanks. The high tank pressure causes the IP to drop so low that they breathe hard. These old regulators work best at the tank pressure they were designed for (1800-2200 psi) and they perform at their peak when coupled with a steel 72 tank. You can use an aluminum 80 filled to 2200 psi, but the buoyancy characteristics of a 72 are a lot better.

This is quoting from a book "The Physics and Engineering of Diving, 1981".

Referring to a double hose unbalanced diaphragm: "The unbalanced diaphragm type regulator will experience an increase in intermediate pressure as the cylinder pressure drops. The unbalanced diaphram should be adjusted at a low cylinder pressure where the output pressure from from the first stage is the greatest. An unbalanced diaphragm type regulator will cause greatest breathing resistance at the beginning of a dive whereas an unbalanced piston type regulator will cause the greater breathing resistance to occur at the end of the dive. The diaphragm regulators usually provide a much wider range of IP than do the piston types".

The US Divers service manual I have for a DA AquaMaster says to tune it to a 110 IP, but it doesn't say at what tank pressure. I set my regulator at 2200 psi. I saw the IP drop to 90 at 2800 psi and rise to 135 at 500 psi. It didn't leak at the low tank pressure so I left the settings where they were. A post from an old Navy diver said that they adjusted the DA AQuaMaster at 500 psi tank pressure. They simply boosted the IP untill the regulator leaked and then backed off until it stopped. That sounds simple enough.

A nicely tuned DA AquaMaster will breathe easy and silky smooth, while delivering big volumes of air. The DA was produced from 1958 to 1972 and was the most popular double hose regulator ever made.

There is a description of equipping an AquaMaster with an inflator/octopus in the thread: http://www.scubaboard.com/showthread.php?s=&threadid=39132

[seahunter]

The thread on the USD Aquamaster regulators (and the Voits) is an absolutely stock air fitting. Any decent supply store that handles welding equipment or services air brakes or hydraulics can sell you the female fitting that screws right on and seals. There is no 'o' ring or sealer. The female fitting has a bull nose that seals tightly in the smooth curve on the inside on the opening on the reg.

Get the fitting with a 1/2" ferrule (looks like a tapered ice cream cone) and you can slide any length of standard air hose over it and clamp it. Now you have an LP hose of any length you want attached to your 2 hose. Use it for filling tires, lift bags, air tools, etc or you can attach a cut-off reg hose for an octopus or an LP hose. In fact, you can easily splice an LP hose and a reg hose so you have both an octopus and a BC.

While it may seem Mickey Mouse to use regular gear (plumber type) clamps and regular air tubing on scuba gear, realize that the pressure is 110 to 150 psi which is the same as the pressure at a service station. The hoses are rated for 250 psi.

[ew1usnr]

seahunter once bubbled...
The thread on the USD Aquamaster regulators (and the Voits) is an absolutely stock air fitting. Any decent supply store that handles welding equipment or services air brakes or hydraulics can sell you the female fitting that screws right on and seals. There is no 'o' ring or sealer. The female fitting has a bull nose that seals tightly in the smooth curve on the inside on the opening on the reg.

True. However the threads are cut into the brass regulator case and THEN chrome plated, making the threads a little thicker and making the cap a little harder to screw on. I stuck an o-ring in there so that I wouldn't have to screw the cap as far down or as tightly as would have been required use the metal to metal fitting. While not absolutely necessary, the o-ring works and everything seals.