With the lid unlatched and removed, the interior layout is visible. The enormous scrubber is flanked by the twin 2-liter cylinders, rated at 200 BAR. Counterlung and breathing plenum is at the top, and the valving is at the bottom.
The valving is quite complex, consisting of the following: Automatic mode change from umbilical to internal on gas-supply loss, constant mass flow system from both umbilical and internal gas system, constant-pressure regulator for the internal cylinders, and the telemetry/sonic signal system for umbilical supply loss.
With the scrubber removed, we can see the counterlung, cylinders, and valve assembly. Unlike other Russian rebreathers, the cylinders are semi-permanently installed, as they were filled in-situ and were not exchanged between dives, the rig not using them as a normal gas supply.
The umbilical supply is located on the left side of the diver, and has a very well-made locking quick-disconnect installed.
The method of securing the hose-barb on the umbilical feed-whip is typically Russian: Simple and effective. The manual devoted a full three pages to the proper method of twisting the stainless-steel safety wire that locks the hose to the barbed fitting.
Here is the "Snakes Nest". It looks complex, but is really just an assembly of individual components that will be described separately. All tubing is of very high quality, and all fittings are silver-soldered in place. No compression fittings are used in any component.
The cylinders were designed to be filled while installed, and the filler port is located on the feed-elbow of the left cylinder. The outlet pipe from this cylinder crosses to the right side of the rig, and one on/off valve positioned at the divers right hip turns on both cylinders.
Positioned at the divers left hip, shown here is the automatic switching assembly that switches the rig to internal gas in the event of an umbilical gas loss. This system also feeds the supply line to the belt-block, thus if the umbilical supply is lost the system deactivates the purge and demand modes of the breathing system. This is done, obviously, to conserve gas when internal supply is used.
In the middle of the pneumatics system we find a dual-assembly of a constant mass flow delivery system, and a constant pressure regulator that feeds this constant-mass system from the internal cylinders.
Here is the top-view of that system. The gauge reads the internal cylinder pressure and is attached to the constant pressure regulator. This regulator feeds gas to the gas-switching system on the left side of the rig, and this then feeds either umbilical gas or reduced-pressure internal gas to the constant mass flow dose system, which is buried under the tubing in the middle of this photo.
On the divers right hip we find the sonic-alarm and telemetry system, which sends signals back to the surface to alarm the life-support technicians if umbilical supply is lost.
The alarm-system is powered by an internal battery as shown here. The cap is double O-Ring sealed and the system should be quite reliable.
The battery is a stack of mercury cells with a shrink-wrapped cover holding them in series. Output is 18 volts.
On our way to the top of the rig, we see that the gas-vent for the exhaust valve is ported to the interior of the shell. This was done to keep the fairly high-volume of exhausted gas from interfering with the divers view. The exhaust valve position is superb, right at the center of the divers lungs.