Biopak 60 is a top-side closed circuit oxygen rebreather used by firefighters and hazmat personnel. It was developed in the mid 70's. The basic design is that of the MK-15 CCRs with back mounted counter lungs located beneath a wide flat axial scrubber.

BP60 can be easily converted to an underwater oxygen rebreather. One needs a suitable DSV, like "The Valve" , as the supplied full-face mask is not suitable for underwater use. Several other items must be exchanged for waterproof equivalents to make unit functional.
BP60 can also be converted to a mixed gas rebreather. Check out excellent teardown at PPo2 web site

Golem Rebreathers took a Franken-Rig approach to the BP60 modification. We used the oxygen injection system from RGU-FM and built electronics module based on the board from PPO2.com. The long DSV hoses are necessary, as the scrubber ports are at bottom left. The next modification will involve rotation of entire scrubber so the hoses exit at the top of the rig.

The RGU-FM dosage unit delivers O2 at 0.9 liter per minute, slightly less than diver metabolic rate. Here, a custom adapter was machined for the RGU-FM regulator to match it to the BP60 plumbing. The button protruding from the case facilitates manual O2 addition.

The sensors are placed in the lid above the scrubber bed. The three display PPO2 monitor is housed in a clear PVC tube closed by custom machined plugs. The sensors are connected with Lumberg cabling and Sealcon cable holders.

The entire unit is mounted on custom-made flat SS backplate with Hogarthian rigging to keep the counter lungs as close to the body as possible.

Diluent is added manually from a side-slung bottle.

The unit was dive-tested several times at undisclosed EDL CzN test location. Further improvements and streamlinig were incorporated into the design cycle.