Here is the unit laid on the bench, with a ruler laid next to the shell for scale. The chassis and shell are made from aluminum, of good gauge for durability, but still very lightweight. You can see the vents for water passage into the shell, and the harness laying under the unit. The top of the unit is to the left. Chock-Full-Of-Nuts coffee can is the result of many late-night sessions working on rebreathers in the shop!
Looking at the top of the unit, we see the automatic/manual add valve and the two hose inlets. Also seen is the substantial pin that latches the shell together. This is a simple and robust way to accomplish latching. Pay attention to the details of the rivets in the aluminum: These are aircraft type rivets, and provide a very strong assembly.
The addition valve acts as a fairly good demand regulator, feeding in 02 as needed to a bottomed out counterlung with little effort at all. For manually purging the system pre-dive, or manual addition, the central purge-valve can be depressed to manually add oxygen. You can use my finger for scale to see how compact this rig really is. It is a very small and light unit, and is a real pleasure to dive.
The high-pressure gauge is easily visible, with very good phosphorescence. Bottom line: it GLOWS in the dark. This view was taken after the harness was unsnapped, and you can see the exhaust valve in the background. The exhaust, like all other components, is made of matte-chrome plated brass. No plastic is used anywhere on the rig. To cater to those who might still desire to sire children after using these rebreathers, we have machined adapters to allow the use of Western (Read: non-radioactive) high pressure gauges. I'm not really sure if the originals are radioactive, but the DO glow pretty well in the dark.
RECENT NEWS: One guy got all bent out of shape thinking I was importing radioactive material without a NRC license. So he took a Geiger Counter and ran a scan on these. Guess what? They are NOT radioactive. They just glow like mad. Sorry to disappoint you!
The harness is furnished with a 'D' ring to allow attachment of the high-pressure gauge by this snap, which I thought was a typically military detail.
Here is a detail of the exhaust valve, which as noted before is of solid brass construction with a good quality chrome plating. Above the valve is the serial number tag. Details of the harness are also visible, with the snaps that attach the harness to the rig. I found that I could simply use machine screws and washers to mount wings to the chassis, and then just looped 2-inch webbing through the existing brackets on the shell to make up a more normal harness that's the same as what I use on my other sport-diving equipment. No modification to the rig was needed at all, other than to drill a few holes to attach the wings.
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The 02 on/off valve is special: You flip a guard and lift the lever to open, push to close. This is very easy to use, and is extremely well engineered. Left photo shows open, the right photo is the valve closed. I was extremely impressed with this device.
The DSV deserves special mention. It is constructed of brass, and features an "Apparatus" setting (Dive) and "Atmosphere" setting (surface). Since it was to be used with a full-face mask, the "Atmosphere" setting allows the diver to breath from the outside Atmosphere while retaining the mouthpiece in his mouth. Since the body is brass, it would be easy to modify this to add a normal SCUBA second stage to allow the DSV to become an open/closed circuit DSV with bailout capability. The DSV is designed to screw on to a full-face mask, although a standard mouthpiece may be stretched to fit. We are working on production of a Delrin adapter that will thread onto the existing DSV to allow a neater attachment of the mouthpiece. This should be available for sale shortly.
The flapper valves of the DSV are not the more usual rubber kind, rather they are rigid plates made of Mica, sprung against their seats by a very finely made stainless steel spring. This is by FAR the best non-return valve system I have ever seen. The work of breathing of the valve is extremely low, and the cost to manufacture this system must have been astronomical.
Here is a good shot of the attachment of the crotch-strap, and you can see the slots for the waist-harness in the background. Again, the unit lends itself to easy addition of a more normal harness. The sliding latch is pushed aside to open the shell, the top pin is removed to remove the shell once hinged open. Very neat indeed.
Once the shell is hinged open, the internal parts are exposed for service. On the right is the oxygen cylinder. Next to that are two scrubber cans. Above that is the counterlung. The high-pressure gauge has been laid on top of the counterlung in this picture. On the scrubbers, you can see the filler ports on the bottom.
Loosening the wing-nuts holding the oxygen cylinder in place, we can lift the bottle from the chassis for inspection and filling. The high-pressure gauge is attached, and the cylinder valve also incorporates the first stage regulator.
A detail of the valve/regulator assembly shows the latching on/off switch on the left, and the outlet ports on the right. The assembly made from chrome plated brass.
One of the components on the regulator assembly is this overpressure valve, which would prevent a blown line should the seat in the first stage regulator fail. This is a common item on technical diving argon inflation cylinders, and is a very nice item to find here as well.
The valve must be opened to fill the cylinder, but the gas is prevented from escaping from the regulator outlet by this push-valve which opens when the supply hose to the rebreather is connected. The small protruding 'tube' visible on the face of this fitting moves in about 1/8 of an inch when the hose is connected, thus opening the gas-flow to the rebreather. This is a fine engineering solution for this need.
Each of the two scrubbers is identical, and they are in turn identical to those used on the more common IDA-71. The color code of a grey scrubber indicates that it is to be used with a normal C02 absorbent. In the IDA-71 one of the pair is color coded blue, to indicate that it is to contain the binary agent known to the Russians as 'HP-1', this being a chemical that produces 02 as it removes C02. In the case of the IDA-64, any normal scrubber material is adequate.
With both scrubbers removed, one can see the inlet and outlet ports of the counterlung. Internal hoses direct the gas flow: Exhaust gas is fed directly into the scrubbers. Gas is then replaced into the counterlung from the scrubbers. Since the two scrubbers run in parallel, the system may be used with only one scrubber if the ports for the removed scrubber are blanked off.
Here you can see that I have installed a pair of brass blanking plugs, custom machined just for this purpose. I have found that with the far better Western scrubber agents, the pair of scrubbers is gross overkill. By removing one scrubber, internal volume is gained in which one may mount a small cylinder to inflate wings or a drysuit, or for some small quantity of open circuit gas. This makes a very clean and neat rig with good capability. If you added an oxygen sensor system, there -are- ways of using this second bottle as a diluent source for conversion of this rig to a nitrox CCR, but if you don't already know how to do this, don't ask me for advice. It's YOUR ass! Like Chuck Yeager said, "I can't recommend it, but it -can- be done...."
Here is the stripped chassis, down to the counterlung and pneumatics supply hose. Not a lot left, is there? This is a very simple system, functionally interchangeable with the LAR-V. I've had a lot of fun with mine, and use it exclusively now when I want to dive an 02 rebreather.
Last but not least, here's the original harness. It slips over your head, and is surprisingly comfortable and very secure. It could be used with conventional wings as well, if you cut slots in the fabric between the wings to run the straps through. You can see the area of holes remaining from where I removed the plated brass bracket that was used for carrying explosives. I kid you not: The bracket that I removed had a slot to engage a stud for carrying anti-ship mines on combat missions. This just brings us back to the idea that although we use these devices for sport and education, they were in fact designed for reasons far more sinister than fish-watching (OK, fish -spearing- for dinner, in my case).