In The Loop
Build your own rebreather

Not everyone has $30 million to invest in a rebreather that they’re not going to use, like the US Navy reportedly did with the Mk-19. For Robert R. Iannello, getting that kind of money would be a lot more complicated than pulling teeth.

A Moreno, California dentist, Iannello was determined to build his own closed-circuit oxygen rebreather on a reasonable budget, using easily-obtained materials. The 30-year diving veteran has come up with what he describes a “hideous-looking, working prototype in research and development”. His final cost? Under $500.

Here’s how he cobbled together his first rebreather: A scrubber canister holding CO2 absorbent was sandwiched between open-cell foam to filter out dusting, and compacted slightly with a closed-cell foam “gasket” to prevent settling/channeling of the absorbent. He made a counterlung out of a UDT swim vest, and to complete the plumbing,, combined a standard double-hose mouthpiece with various fittings from the local hardware store. High-pressure systems consisted of items designed for oxygen use (pressure vessel) or oxygen cleaned and converted (regulator). The unit was pool-tested for system integrity, and after rectifying a series of design errors-including a free-floating counterlung that acted like a lift bag attached to his Adam’s apple(!)- Iannello finally got his contraption working for a 45-minute dive at a maximum depth of 25 f/7.7m, with 1.5 liters (should read cubic feet) of gas consumption.

It may not be beautiful-and it’s certainly not going to replace his open-circuit scuba--but Iannello now has a one-of-a-kind conversation piece. He says, “A CCO2 rebreather can contain [such] low-technology that I’m surprised that we have not heard of more divers making them.”

Manufacturing a mixed-gas rebreather is, of course, more complicated-and costly-than making a simple O2 one. But one can’t help but wonder: Maybe the Navy should have called him up and saved us taxpayers a bundle of cash.