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Franken-Rig Mechanical Assembly

Once we have PP02 measurement and an 02 injection system, it's then just a matter of mechanical fit. One extra slot needed to be added at the bottom for the on/off valve, and one had to be enlarged for the manual bypass button. This took 5 minutes with a step-drill and a file.

The original clamps in the lower area of the rig were not located correctly, and were too large for the cylinder. I cut one extra slot and added a hose-clamp. We're getting closer!

Once that was done, the cylinder just dropped right in. Here's the complete oxygen circuit: The bottle is at the bottom of the chassis, with the on/off valve protruding through the bottom. The manual add valve sticks out through the left side of the rig. The 02 is added to the counterlung through a length of tygon tubing, into the brass adapter described earlier. That's it! I need to machine an adapter to add a pressure gauge to this bottle and it'll be perfect.

Now I've added back the original cylinder and the scrubber. The whole system is extremely simple, and should be reliable in service.

Here's the rig, ready to go. Diluent on the right, scrubber in the center, 02 across the bottom. Next I'll add a small battery pack for a cannister light on the left and it'll be even better.

A bottom view of the closed rig shows the flat on/off knob for the 02 bottle, the manual add valve sticking out from the side, and the exit for the cable to the PP02 gauge. All controls are easy to reach, and the flat knob resists damage. The bottom latch of the rig actually hits the ground first when the rig is set down on the deck, protecting the 02 valve.

The Russians thoughtfully provided a nice slot through which the Oxyguage cable may be lead. Nice of them wasn't it?

Here's the final modification: The automatic add valve is located at the top of the rig. It's just a diaphragm second stage, and works well. I drilled a hole in the plastic cover to allow a finger to poke in to press the diaphragm so it acts as a manual diluent add valve as well. Neat, eh? The port at the left side is the exhaust valve exit. Although the actual exhaust valve is against the small of the divers back, the exit gas is ported through the counterlung and exits the top of the rig, so as to not impair the divers visibility with bubbles.

That's all it took to make this into a neat Nitrox CCR. It's simple, manually operated, and has the advantage of needing very few manual additions of 02 due to the slow trickle of 02 passing into the rig at all times. The fact is that in just a few hours I had taken two rigs, joined them at the waist, and produced a nice little recreational rig. To say I am pleased is an understatement!

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	Once we have PP02 measurement and an 02 injection system, it's then just a matter of mechanical fit. One extra slot needed to be added at the bottom for the on/off valve, and one had to be enlarged for the manual bypass button. This took 5 minutes with a step-drill and a file.
	The original clamps in the lower area of the rig were not located correctly, and were too large for the cylinder. I cut one extra slot and added a hose-clamp. We're getting closer!
	Once that was done, the cylinder just dropped right in. Here's the complete oxygen circuit: The bottle is at the bottom of the chassis, with the on/off valve protruding through the bottom. The manual add valve sticks out through the left side of the rig. The 02 is added to the counterlung through a length of tygon tubing, into the brass adapter described earlier. That's it! I need to machine an adapter to add a pressure gauge to this bottle and it'll be perfect.
	Now I've added back the original cylinder and the scrubber. The whole system is extremely simple, and should be reliable in service.
	Here's the rig, ready to go. Diluent on the right, scrubber in the center, 02 across the bottom. Next I'll add a small battery pack for a cannister light on the left and it'll be even better.
	A bottom view of the closed rig shows the flat on/off knob for the 02 bottle, the manual add valve sticking out from the side, and the exit for the cable to the PP02 gauge. All controls are easy to reach, and the flat knob resists damage. The bottom latch of the rig actually hits the ground first when the rig is set down on the deck, protecting the 02 valve.
	The Russians thoughtfully provided a nice slot through which the Oxyguage cable may be lead. Nice of them wasn't it?
	Here's the final modification: The automatic add valve is located at the top of the rig. It's just a diaphragm second stage, and works well. I drilled a hole in the plastic cover to allow a finger to poke in to press the diaphragm so it acts as a manual diluent add valve as well. Neat, eh? The port at the left side is the exhaust valve exit. Although the actual exhaust valve is against the small of the divers back, the exit gas is ported through the counterlung and exits the top of the rig, so as to not impair the divers visibility with bubbles.