Diving helmet
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Diving helmets are worn mainly by professional divers engaged in surface supplied diving, though many models can be adapted for use with scuba equipment.
The helmet seals the whole of the diver's face from the water, allows the diver to see, provides the diver with breathing gas, protects the diver's head when doing heavy or dangerous work, and usually provides voice communications with the surface (and possibly other divers). If a helmeted diver becomes unconscious but is still breathing, the helmet will remain in place and continue to deliver breathing gas until the diver can be rescued. In contrast, the scuba regulators typically used by recreational divers must be held in the mouth, and will usually fall out of an unconscious diver's mouth resulting in drowning.
Before the invention of the demand regulator, all diving helmets used a free-flow design. Breathing gas was delivered at a constant rate, and whatever gas the diver did not inhale was exhausted through a valve. Most modern helmets incorporate a demand valve, which is essentially a scuba regulator. This means that the helmet only delivers breathing gas when the diver inhales. Free-flow helmets use much larger quantities of gas than demand helmets, which can cause logistical difficulties and is very expensive when special breathing mixtures, such as heliox, are used. They also produce a constant noise inside the helmet, which makes communication with the surface more difficult. Free-flow helmets are still preferred for hazardous materials diving, because their positive-pressure nature can prevent the ingress of hazardous material in case the integrity of the suit or helmet is compromised.
Most helmet designs can be sealed to the diver's suit via a "neck dam." When worn with a drysuit, this keeps the entire head and body isolated from the surrounding liquid, giving an additional degree of warmth. In hazardous environments such as sewage or dangerous chemicals, a helmet (usually of the free-flow type) is sealed to a special drysuit (usually made of thick rubber) to completely cover and protect the diver. This equipment is the modern equivalent of the historic Mark V "Standard Diving Dress", and is commonly referred to as "heavy gear."
Types
Historically, deep sea diving helmets ranged from the two bolt to four bolt helmets; helmets with six, eight, or 12 bolts; and Two-Three, Twelve-Four, and Twelve-Six bolt helmets.
Notable modern commercial helmets include the Kirby Morgan Superlite-17B from 1975 and developments from that model. These helmets are of the demand type, built on a fiberglass shell with chrome-plated brass fittings, and are considered the standard in modern commercial diving for most operations. [2]
There are also Dinosphere diving helmet, designed and manufactured by Croatian diver Mr. Dino Matkovic. These helmets are something brand new in the world of diving; created both for professional and recreation divers, this helmet weight only 10 kilos. One of the best features of the Dinosphere diving helmet is that you can attach any regulator/octopus/hose on it... So its perfect bot for self-supplied divers and surface-supplied divers. Dinosphere pass trough all the tests ;it was also tested in Tucepi, Croatia at 19th of August 2009. by Dino Matkovic and Andrej Gajic (diver).[citation needed]
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Dinosphere diving helmet on assaying -
Andrej Gajic, just before the dive -
Dino and Andrej preparing for the diving and assaying, by: Benjamin Dzaferovic -
Yeah, here we go!
The Desco "air hat" is a metal free-flow helmet, designed in 1968 and currently produced. Its robust and simple design (all maintenance can be performed in the field with only a screwdriver) makes it popular for shallow-water operations, and especially hazardous material dives.
Light-weight transparent dome type helmets have also been used. For example the Sea Trek surface supplied system, developed in 1998 by Sub Sea Systems, is used for recreational diving.[3]. Also the Lama, developed by Yves Le Masson in the 1970s, has been used in television to let viewers see the face and hear the voice of the presenter speaking underwater. [4]
History
See Diving helmets appear for the history of the diving helmet.
Augustus Siebe is known as the father of Diving. In the year 1837 German-born inventor Augustus Siebe, then living in England, developed a Diving Helmet which was sealed to a watertight, air-containing rubber suit. The closed diving suit, connected to an air pump on the surface, becomes the first effective standard diving dress, and the prototype of hard-hat rigs still in use today. In his obituary Siebe is described as the father of diving.
Siebe Gorman & Co was notable for developing the “closed” diving helmet of the standard diving dress and associated equipment. As the helmet was sealed to the diving suit, it was watertight, unlike the previous “open” helmet systems. The new equipment was safer and more efficient and revolutionised underwater work from the 1830s.
However, Alexander McKee proposed that brothers John and Charles Deane were the true inventors, and that Siebe was the leading manufacturer of their designs.[5]
Nowadays
An alternative to the diving helmet that allows communication with the surface is the full face diving mask. These cover the diver's face and are held onto his head by adjustable straps.
"Diving helmet" sometimes means a hard safety helmet like a workman's helmet that covers the top and back of the head, but is not sealed. These may be worn with a full-face mask to provide impact protection.
During the First World War the British Army used a few diving helmets out of water as emergency protection from mustard gas.
See also
References
- ^ Curley, MD (1986). "Human Factors Evaluation of the Superlite 37B Helmet in the Surface- Supplied, Open-Circuit Mode". US Navy Experimental Diving Unit Technical Report. NEDU-11-85. Retrieved 2008-09-09.
- ^ Kirby Morgan DSI dive helmets
- ^ Sea Trek dive helmet
- ^ Lama dive helment
- ^ The Infernal Diver by John Bevan, Hardcover - 314 pages (27 May, 1996), Submex Ltd; ISBN 0-9508242-1-6