Technology has enjoyed considerable advances since the Polly-Gaff’ Gas Analyser was first announced – almost thirty years ago, in the May 1997 pages of Scuba Diver Magazine
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The inherent problem with gas analysers is their frailty. While primary diving equipment is designed to withstand the rigours of harsh environments the support instrumentation is often less robust and hardy.
During ‘normal’ no-decompression recreational diving a computer or gauge failure usually means nothing more serious than a controlled ascent back to the surface. But in certain aspects of technical diving such a failure can prove catastrophic.
This is a matter of particular concern in Closed Circuit Rebreather use where the diver is dependent upon maintaining – regardless of depth – the oxygen content of the breathing gas at a safe partial pressure. An aspect of CCR use that places a heavy reliance on sophisticated instrumentation to achieve this constant; one that, in some instances, employs multiple redundancy systems in the event of a primary failure. While this obsession with safety is justified it does place enormous strains on the resources of most divers, particularly during extended field trips.
Invited to seek an inexpensive solution to the problem, Zymurgy Inc. brought their vast expertise to bear. Drawing on the lessons learned by other industry groups faced with the problem of maintaining life in potentially hostile atmospheres they came to the conclusion that a biologic monitoring device was the answer.
Faced with the ever-present risk of drilling into pockets of poisonous gas, coal miners of the last century were in the habit of carrying with them a canary in a cage. With its high metabolic rate the canary would quickly succumb to the effects of changes to the atmosphere and provide the miners with advance warning of impending danger.
Employing state-of-the-art plastics technology, Zymurgy Inc.’s design team have created a small pressure-resistant bell jar with screw-in base plate, ‘O’-ring seals and a centrally located, non-return inlet valve to which is attached a small hose that plumbs directly into the counter-lung of all currently available CC Rebreather models. With an adjustable exhaust valve located on the crown, the jar also contains a small wooden swing, and two small containers, one holding bird seed and the other filled with water.
Considerable research went into selecting the appropriate type of bird, the team ultimately deciding on a miniature Australian parrot renowned for its non-stop squawking.
Once the parrot is introduced into the jar and the base securely sealed the whole assembly is clipped to a gimbal mounting on the diver’s left shoulder in close proximity to his ear.
Exhaustive tests on the ‘Polly-Gaff’ gas analyser showed that while the parrot was exposed to the same breathing mixture as the diver he continued to chatter and squawk, a sound easily carried to the diver’s ear by virtue of water’s greater density.
When, however, the PO2 falls below 0.5 or rises above 1.4 Bars then the parrot will usually fall from its perch and cease to make any noise at all, an immediate indication that drastic changes have occurred to the oxygen content of the breathing mixture.
Although a few wrinkles still remain to be ironed out it is thought that the ‘Polly-Gaff’ will, through its novel use of biologic controls, add a new dimension to deep diving research.
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Categories: Counter-Strike
NEKTONIX 