Welcome to the IDA71 (UK) Website

The IDA71 Rebreather is a Russian Navy unit that was first produced in 1971, hence the 71 designation. It is still in use today.

It is a fully closed system (CCR) & has no electronic parts as standard. Instead it was designed as a pure O2 unit down to 15m, or down to 40m with Nitrox 40.
Now before anyone says that this is way over the accepted PPO2 limits, well in 1971, the currently accepted limits were unknown!.

When used with Nitrox, there is an external cylinder to supply Nitrox to the system, this incorporates an automatic loop blow through device that purges the loop of pure O2 (1L bottle)when you descend below 12-18m depending on temperature!, & during the ascent it purges the loop of Nitrox at the same depth!. It is connected via a self sealing connector on the base of the unit & the external 1L bottle is mounted on your belt. The connector coupling contains a pressure balanced valve that auto disconnects the O2 feed to the demand valve when the Nitrox is connected.

The system is able to use Nitrox as a dilutant during deep dives because the Russains fill one of the scrubber packs with what they call O3, this is a scrubber chemical that gives off equal amounts of O2 for amounts of CO2 removed. This is a very dangerous substance, which when exposed to salt water will go exothermic!. You don't have to breath the caustic cocktail it will come down the hose looking for you!.It was this substance that caused the fire on the MIR space station.

I have modified my unit in the following ways.
1. Removed auto purge system.
2. Added two Dreager Oxygauges to monitor PPO2.
3. Added manual O2 addition via an adj metered valve.
4. Added Scubapro Full Face Mask.
5. Added Scubapro S-Tek Harness & Buddy Redwing bladder.

1. Internal View 2. The Back Cover 

3. Another View

4. Diagram of gas flow 5. Close up of O2 take off

These modifications give a theoretical maximum duration of 3hours at any depth (1L/min O2 consumption rate) to a 40m maximum & the scrubbers hold 1.75Kg each (3.5Kg total) & give an average 8 hour's duration.

6. O2 Control Valve 7. Dreager Oxygauge

I can maintain the PPO2 within a ><2% range of the Nitrox supply gas, this allows me to use a normal Nitrox computer for deco info. I can also go onto high or pure O2 at decompression depths, this is achieved by simply turning off the nitrox cylinder, then increase the O2 flow valve setting & slowly vent the loop. This compensates for the small discrepancies in FO2 during the dive.

The O2 flow control valve in these pictures is rigged for testing, now that I know it works OK it has been mounted on the casing just above the O2 valve.