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How a small 1984 Fency rebreather can be rebuild to a nice oxygen rebreather 29 december 2013

Dear Janwillem,

Here are some pictures of my adapted Fenzy escape rebreather. It is a 1984 NSN4240 and I acquired it without its original O2 bottle. Intrigued by the little rig I set about exploring other ways to mount a cylinder, basically to see if it could perform like a latter-day DSEA or a mini ARO.

When I got the rig there was a lot of nasty old foam insulation and thirty year-old absorbent in the scrubber which had to be removed. The original overpressure valve was stuck and the O2 inlet manifold had to be sealed, so these issues were fixed as part of the upgrade. Taking inspiration from the CEDU, I opted for a field expedient O2 bottle (1ltr / 110 bar) and regulator from a home welding kit. The bottle is mounted underneath the counterlung using diving knife straps and a rod passing above the waist belt fixture. This makes it easy to 'feather' the valve and add gas as required.

Duration is about 1 hour under minimal workload! Scrubber holds 1.25kg of sorb. I also use a DSV from a Naubos AR88 with it (pictured). The WOB is slightly worse than the original Fenzy DSV as it has a smaller bore, but the AR88 DSV makes pre-dive purges much easier.

It is a cute little pendulum rig for lazy Sundays spent at 5m.

Happy diving and best wishes for 2014!


Cornwall, UK

Fency NSN4240_01
Fency NSN4240_02
Fency NSN4240_03
  James, thanks for sharing this information! 29-12-2013
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