R for RECYCLER

Definition

Respiratory system intended for underwater exploration which recycles the gas exhaled by the diver through a filter cartridge which fixes the carbon dioxide and which therefore becomes breathable again, without untimely losses. It is the “green” diving suit par excellence, which, if I dare write, does not lack air…

Synonymes

Closed circuit diving suit | Semi closed circuit | CCR (closed circuit rebreather) | Rebreather | “Machine” |

Starter

It's a fact, an observation: against all expectations, rebreather diving suits have now invaded diving boats, with dozens of different models, operating and maintenance modes, with their hundreds of trinkets and flashing screens and, for their users, so many training, skills and sometimes contradictory safety rules. From then on, for the instructor, composing a homogeneous team became the squaring of the circle. Very often, out of breath transporting a 15-liter steel while spitting bubbles towards a disappeared surface, too long and too deep with the key air failures and endless stops “in apnea”, we find ourselves following a ghost that skirts in the dark, without bubbles, indifferent to past time, depth and future levels… A trend that will only increase in the future as the advantages of recyclers are numerous compared to the traditional “open circuit” of yellow bottles dad's…

Indeed, since we consume less gas, the duration diving is considerably increased at the cost of an equivalent size. Out of the water, the material is therefore much lighter. Insofar as we breathe mixtures richer in oxygen, the duration of the stages are correspondingly reduced. The machine is very silent, which in principle makes it possible to approach the fauna more closely. Especially since the rejection at the option of breathing noisy and polluting bubbles (when diving “under the ceiling”) is by definition suppressed.

The very notion of recycling and the exothermic reaction of the gas passing through the lime cartridge, leaving its CO02 behind, leads to breathing a hot and humid gas, which reduces heat loss and the risk of equipment frostbite; particularly important points during dives in cold or long and deep water. Finally, depth, accessible much more easily by the changes of gas mixtures during the dive and the ascent with all the electronic instrumentation intended to facilitate and shorten it. Today, an expedition on wrecks or underground exploration is no longer considered without the use of one or more recyclers ...

Main course

On the downside, the price, of course: it's expensive. Very expensive. Yes, yes, more expensive than that, even… The maintenance, equivalent to that of a luxury car or, in another currently very controversial and “politically incorrect” register, the maintenance of a “dancer” or other cagole of good quality. Finally, the complexity of the whole, which requires real expertise and in any case specific training. And paying ... 

Indeed, we no longer dive in the same way with rebreathers as in “open circuit”, as during the training courses of yesteryear. It was simple: a bottle, a regulator, a mask and fins and, in a pinch, a swimsuit! You only have to watch the black and white mermaids evolving in tri-bottles in Mediterranean waters, next to the wonderful literature of the books of Philippe Diole to be convinced. No buoys, life jackets, weight belts: buoyancy was regulated with crystal bubbles using the basic technique: the “ballast lung”. We blow: we sink; we breathe: we go back up. Simple I tell you! At that time, we knew how to breathe ...

Ballast lungs?

However, in a recycler one is permanently balanced; when the lungs deflate, the breathing bag inflates, canceling out the effect: buoyancy remains zero. A destabilizing feeling that you have to learn to master. To sink or stop an untimely ascent ...

Of course, I have had the opportunity in the past to play with several military recyclers and even participated in Florida, in the company of Sheck Exley, to the test dives of Cis-Lunar, one of the first “civilian” closed-circuit diving suits invented by the brilliant engineer and underground diver Bill Stone. But it was the use of Oxygers, pure oxygen diving suits for combat divers in principle limited to -7m, which made me experience for the first time the disappearance of the “ballast lung”, this unpleasant feeling of suffocation by “Too much air” while the body no longer obeys…

One drunken evening we decided to take pictures in the Green Lake, a setting of fluorescent green water filled with beautifully submerged trees, an altitude lake of transparent and icy water accessible at the price of 2 hours and 30 minutes of walking in the mountains of Italian Piedmont above Turin. Considering the approach conditions, we had given up on weight belts (replaced on site by stones placed in a net), on bottles for which we had substituted two Oxygers and even on waterproof clothing despite water at 5 ° C. We planes opted for 3mm “single skin” and “close to the body” hunting suits, but above all very light. Needless to say we've been staring at each other for a long time, Eric Coutinot and me, to find out who would get into the melted ice first. History has forgotten him even though the operation, carried out in almost mortuary silence, took… some time.

Still, at a certain moment, my arms cluttered with cameras and flashes, I passed the engulfed graveyard of trees and felt myself climb up, against my will. Force of habit, I huffed just enough to regain my balance and depth. But nay, I still went up and felt my lungs swell more than reason: the air I exhaled only inflated my belly breathing bag! And vice versa. Until, at the last minute, I think about pushing the excess gas out through the nose, through the mask. Serious but saving breach of the sacred rule of “mouth breathing”…

It is not the least of the paradoxes to note that these “modern” rebreathers, in the process of making obsolete the classic cylinders and regulators “Cousteau-Gagnan in the practice of recreational diving, are of invention considerably older than these latter.

Dessert

The principle of the chemical fixation of toxic carbon dioxide in the air breathed was indeed known for a long time. Around 1620, in England, Cornelius Drebbel manufactures first rowing-propulsion submarine. To oxygenate the air inside, he heated saltpetre (potassium nitrate) in a metal saucepan. The heat then transformed the saltpeter into oxide and potassium hydroxide, which absorbed carbon dioxide from the air. This explains why the men of Drebbel were not bothered by the build-up of carbon dioxide. More than two centuries before the first patents ...

The first rebreather diving suit, based on the absorption of carbon dioxide, was patented in France in 1808 by Sieur Pierre-Marie Touboulic a native of Brest, a mechanical engineer in the imperial navy. It operated with an oxygen tank controlled by the diver and which circulated in a closed circuit through a sponge soaked in lime water. Touboulic had named his invention theIchtioander (“Man-fish”, in Greek) but it is not certain that a prototype was made. On the other hand, history has retained the name of French Pierre-Aimable De Saint-Simon Sicard, inventor, chemist and businessman who took out a patent in 1849 for a system called “chemical saving device and system” comprising in addition to the recycling device, a helmet with valve, a cloth suit and a lamp underwater. The apparatus was supplied by two copper cylinders containing 150 liters of pure oxygen. An invention followed in 1853 by that of the professor T.Schwann in Belgium. Consisting of a large oxygen tank mounted at the rear with a working pressure of approximately 13,3 bars as well as two scrubbers containing sponges soaked in caustic soda ...

But the first commercially operated closed circuit device was designed and built in 1878 by the dive engineer Henry fleuss, who was working at the time for Siebe gorman in London. His self-contained breathing apparatus consisted of a rubber mask attached to a breathing bag, a copper reservoir providing a 50-60% oxygen mixture. CO₂ excess was absorbed by a cord soaked in a solution of caustic potash (KOH); the system theoretically allowing a dive time of about three hours. Fleuss tested his device in 1879, spending an hour submerged in a water tank, and a week later, diving to a depth of 5,5 m in open water ...

It was in 1880 that the Fleuss was used for the first time “in full size” by the legendary chief diver Alexander lambert at the construction site of the river tunnel Severn in England. As the tunnel was accidentally submerged, it was absolutely necessary for a man to dive into the murky water and manage to close several lock gates at its end!

Lambert was thus able to travel more than 300 m to 10 m deep, in total darkness and in the middle of debris floating in the current to succeed in the mission; The best traditional “heavy-foot” divers had to give up because of the strong currents and the great distance to cover which damaged their air supply pipes. From there was probably born the trivial expression: to have the testicles in hardened steel ...

See you soon for a new definition of Scuba Bécédaire. The irreverent lexicon of diving, but not only. Because sometimes ...

Francis Le Guen

 

 

Café

A demonstration of the benefits of the recycler by the friend Vincent Defossez of the Center Aquadomia à Marseille. The recycler? Everyone will be there, one day or another ...