Helmet diving device
A helmet diving device is a diving helmet made of metal or plastic with an air inlet and outlet, which is connected to a diving suit . Helmet diving devices were the first diving suits and were primarily used by professional divers .
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history
Marianus Jacobus first describes a diving suit with helmet around 1438, before Leonardo da Vinci around 1500. After the diving bell , the Englishman John Lethbridge developed a diving barrel in 1715 , which he named diving engine . It was an approx. 2 m long wooden barrel in which the diver lay down and put his arms through two openings with leather cuffs on the underside, which were tied off to make them watertight. A lid was then screwed onto the head side. There was a viewing window in front of the diver's face. On the surface of the water, air was supplied through a bellows through two openings that were closed with plugs immediately before lowering. This enabled longer work at depths of up to approx. 20 m. As working with a replica showed, the activity was very painful for the diver due to the lack of pressure compensation.
As early as 1797, Karl Heinrich Klingert from Breslau presented an early helmet diving apparatus. The diver wore a short-sleeved leather suit; a wide metal ring should protect against water pressure up to 6 m deep. Additional rings sealed the suit on the arms and legs. The helmet had a relatively large diameter and two small viewing panels in front of the diver's eyes. Klingert proved the basic functionality of the device by sawing a tree trunk in the Oder.
In July 1800, the captain Peter Kreeft from Barth (Western Pomerania) demonstrates a helmet diving apparatus ( diving machine ), the helmet of which was bent from iron rods, covered with leather and provided with a large window. The air was pumped down with a hose and escaped down through a cloak made of canvas. Approx. 200 years later, a replica showed the functionality of the device.
In 1819, the British-born Augustus Siebe built a surface- treated diving helmet. This was open on the underside, excess air escaped below. The suit could overflow from water if it was improperly positioned or if the air supply was interrupted. The practical suit found its first users, the simple form of the diving helmet can be found to this day.
In 1838 Siebe developed his diving helmet further by combining it with a suit. The essential features of the helmet diving devices that are still in use today were thus developed. The diving equipment developed by Siebe was commercially manufactured in large numbers by Siebe Gorman and was used for decades as standard diving equipment for commercial and military purposes ( Standard Diving Dress ). It was produced by various companies around the world and is still in use today.
In 1912, the Drägerwerk in Lübeck launched the first helmet diving device with an oxygen rebreather.
Open and closed helmet, light helmet
The "classic" helmet diving device developed by August Siebe , also referred to as the heavy helmet diving device (STG), was and is partly the standard device for professional divers to this day . Because of the limited possibilities (mobility, etc.) it is now being replaced more and more by lighter helmet diving equipment, which enable the diver to swim underwater and which can be put on and taken off more quickly.
- With an open helmet, the air escapes downwards through the shoulder piece or suit vest into the water. A separation of helmet and shoulder piece is not intended. Original design of the helmet diving device, to this day for simple work, as a do-it-yourself device and in use in shallow water. The helmet itself is usually cylindrical or box-shaped made of metal, and the large square lens is protected by a grille. If the diver bends over or if there is no air supply, the helmet runs full of water. You can get out after separating the belt or weights.
- The traditional, closed helmet device consists of the suit connected to the helmet in a watertight manner, a (mostly) metal spherical helmet, the shoulder piece, weights for the chest and shoulder, lead shoes and the air supply via surface connection . The front window can be opened on the surface. A distinction is made between the following models:
- 3-bolt helmet : The neck opening is stretched for entry by the diving assistants. When diving, the opening between the helmet and shoulder piece is clamped with the three screws, there are practically no problems with the tightness. The design common in Europe and elsewhere, still widespread in Russia today .
- 7-bolt helmet (5-bolt etc.): The neck opening is designed wide enough for entry and is screwed to the edges of the shoulder piece with one (or more) clamping pieces during the dive. The helmet is screwed onto the shoulder piece or attached with a bayonet lock.
- The more modern light helmet is a further development of the closed system. The synthetic helmet is provided with an inner mask, a neck ring with a neoprene membrane seals the neck and closes to the helmet with a bayonet lock. Breathing is usually done with a regulator, the head is protected by a padded hood, and a device enables pressure equalization through the nose. The field of vision is often better, the breathing gas consumption is lower, and additional lead weights on the helmet help balance the helmet. The helmet can be worn with dry suits , hot water suits or wet suits , swim fins allow greater mobility compared to the early lead shoes.
The traditional helmet diving equipment
The diving suit
The tightening of the helmet diver is a waterproof dry suit running. As a rule, it is made of sturdy fabric with a rubber coating . It has three openings, one for the head and one for both hands. Entry is via the neck opening. Since the suit keeps the diver dry but does not offer any thermal insulation, it is necessary to wear an undersuit as protection against the cold. The hands exposed to the sea water are protected with grease or, more modern, gloves.
The actual diving helmet
The diving helmet is usually made of copper or brass . It is screwed onto a neck piece (also made of copper or brass), which is placed on the diver's shoulders after entering the waterproof suit. There are 3 to 4 windows in the helmet that allow a view to the front, left, right and, if available, upwards. The front window is only screwed in immediately before diving. Later models (e.g. Dräger DM 220) have a larger folding window at the front, which makes the side windows superfluous. The helmet is also no longer made of metal, but of glass fiber reinforced plastic.
A drain valve is integrated in or on the helmet, which the diver operates at short intervals by hand, with his chin or with his skull. An automatic valve is often also available. Discharging the used or excess air enables the diver to regulate the amount of air in the suit and thus control the buoyancy .
The fresh air duct inside the diving helmet is often designed in such a way that the viewing windows are prevented from fogging up due to the moisture exhaled by the diver. A check valve prevents the suit from being sucked out through the umbilical cord in the event of supply problems.
The weights
Since the suit is intended to enable underwater work in all body positions, the weights must be evenly distributed. In addition to the helmet and neck piece, metal shoes (steel or brass, in some cases also lead), chest and back weight ensure this. In addition or as a substitute, there are seat weights (Dräger), weight belts and, above all, compensating weights on the helmet and breathing apparatus.
The belt harness used to fasten the weights also has the task of pressing the diving suit against the body of the diver and preventing uncontrolled, excessive inflation. Overall, the equipment weighs between 80 and 100 kg, which is partially compensated for underwater by the buoyancy of the air contained in the suit. The classic helmet diver can work standing, sitting or lying down thanks to the even weight distribution. The device is not designed for floating locomotion; the diver goes over the bottom.
The air supply
This is done either from the surface through a hose or through a self-sufficient breathing apparatus.
The hose-supplied device is connected to a pump on the surface, which continuously supplies the diver with air. Depending on the equipment, the telephone connection and suit heating (hot water) are also ensured by the hose connection. A safety and signal line as well as a descent rope complete the equipment.
In the event of a malfunction, depending on the equipment, the diver can breathe briefly from an additional reserve tank that is at chest weight. In some cases, a back bottle similar to the compressed air breathing apparatus is carried. The emergency supply should allow an emergency ascent or a return to the diving bell. In previous deep dives with breathing mixtures, gas consumption was further minimized by a soda lime canister mounted directly on the helmet.
In the case of the independent rebreather diving device , the diver has a supply of breathing gas, which is not released into the surrounding water with every breath, but is cleaned of the carbon dioxide in the exhaled air by a supply of soda lime . If necessary, additional oxygen or a further breathing gas mixture can be supplied from an additionally carried bottle. This enables the diver to work underwater for several hours. Such an oxygen circulation device is also used by the frogman or the combat swimmers .
An example of an autonomous rebreather for helmet diving use was the DM 40 developed by Dräger in 1912 . The DM 40 is basically a normal, semi-closed rebreather device (SCR), with the difference to the normal SCR that the breathing gases are not pushed through the device circuit by the diver's breathing effort, but by the so-called Venturi effect, which is created at the injector by the influx of the oxygen / air mixture (O 2 content 60.5% when using 50% air and 50% oxygen), and which leads to a constant air flow of 40 to 100 l per minute (depending on the depth) sucked out of the helmet, blown through the CO 2 absorber and past the injector nozzle, back into the helmet. In order to ensure that the volume flow through the helmet is still large enough even at a depth of 40 m (minimum at 40 m depth 40 l per minute), the pressure and thus also the volume flow of the oxygen / air mixture is dependent on the ambient pressure from approx 3.6 l / min increased to approx. 5.4 l / min at a depth of 40 m (volume flow always calculated based on surface pressure).
The DM 40 can theoretically be used for a diving time of four hours and a diving depth of 40 m. Although Dräger issued these diving times as a recommendation earlier (at least until 1949), in later years Dräger recommended a maximum diving time of two hours in order to have sufficient reserves in the soda lime. In addition, the limit values for O 2 pollution recognized today as valid automatically mean that these extreme times are no longer exploited during somewhat deeper dives. Even the diving depth of 40 m no longer meets today's safety requirements (too high O 2 concentration).
The compressed air breathing apparatus can also be found as an emergency device or as a use of regular diving technology in helmet diving professional divers. The relatively low breathing gas consumption at shallow depths makes it possible to dispense with the air supply from the surface; the diver's behavior approaches that of a recreational diver.
The surface connection
The diver is connected to his signalman by a safety line. The communication takes place via train signals. There is also a telephone connection and of course the air supply.
Helmet diving today
Modern helmet diving
Helmet diving is now also known as surface supplied diving . Today's helmet diving equipment is more like conventional diving suits with a collar instead of a shoulder piece and a light helmet, but they are still intended and suitable for heavy work under water. The modern helmet often has a device for pressure equalization via the nose and an inner mask, and a radio connection is also possible.
Modern diving helmets can be divided into two basic classes: First, the so-called free-flow helmets, in which the breathing air (or the corresponding gas mixture) flows constantly and evenly into the helmet (as with the old copper helmet) and the diver usually the head can also move freely in the helmet. Representatives of this class are, for example, the Dräger DM220, the Aquadyne AH3 (or its predecessor), the DESCO Air-Hat or the DESCO Lightweight-Helmet, which looks very reminiscent of the historical diving helmets, but only half as much is difficult.
The second category is the so-called demand helmets. In these, the helmet is usually firmly attached to the head, and the mouth and nose are in a separate inner mask. The air is supplied via a regulator that is firmly attached to the helmet and practically corresponds to the 2nd level for recreational divers. The functionality is therefore similar to that of full face masks or band masks. Examples of such helmets are the Kirby Morgan Superlite helmets.
A feature that all modern diving helmets have in common: They can be permanently connected to a dry suit (important for diving in contaminated water). Most of them (with the exception of Dräger DM 200 / DM 220) can, however, also be worn without being connected to the diving suit, as they are all supplied with a sealing neck seal.
When it comes to materials for modern diving helmets, carbon fiber reinforced plastic has prevailed in recent years . B. with the most famous representatives of this class, the Kirby Morgan Superlites is used. But there are also helmets made of brass, such as the Miller 400 and the DESCO diving hat.
Helmet diving in classic equipment today
In professional use, the classic helmet diving device with a copper helmet becomes less important. Associations for the preservation of historical diving technology in museums (e.g. Historical Diving Society ) collect diving equipment from different eras and keep some of it in working condition. Because of the adventurous nature of diving with a helmet diving device, interested and recreational divers are offered this opportunity in some places by commercial diving schools. The field of historical diving is born.
Dangers / problems
Blow-up
The diver must keep the amount of air in the suit under control. Too much air in the suit can cause the diver to emerge unintentionally. As the depth decreases, the air in the suit continues to expand, the diver gains additional buoyancy and his ascent accelerates further. The tightly inflated suit deprives the diver of any movement. The rapid uncontrolled ascent can lead to the occurrence of diving disease . The nitrogen dissolved in the blood under pressure rolls off and collects in the body. The result is temporary or permanent pain, e.g. B. in the joints, paralysis or, in the worst case, death. Death by drowning was also threatened with old suits if the suit burst as soon as the diver was pushed up beyond a certain depth. Blow-ups to the surface from a depth of approx. 9 to 14 meters were not dangerous for the durability of the suit.
Pressure equalization
During the descent, the rising water pressure is quickly felt by the pressure in the ear for every diver . The swimming diver with a mask can counter this by exhaling into his nose. The helmet diver cannot get to his nose. This can be remedied by swallowing or a nose clip. The latter, however, is disadvantageous in that the diver can only breathe through the mouth. This can be uncomfortable, especially during long, hard work.
Skin bruises
Creases in the suit can cause painful bruises in the skin. The so-called blue coming is also a possible type of injury while helmet diving.
Rupture of the hose
Through the hose, the diver receives air that corresponds to the pressure that surrounds him in the water. If the hose breaks, the pressure in the suit drops, so that the diver's body is pressed into the helmet as the only pressure-stable cavity (so-called squeeze ); the diver is “pureed”, so to speak. On the other hand, a non-return valve is built into the helmet , which closes immediately if the pressure drops. The diver is forced to surface immediately, but is not in immediate danger. Regarding the dangers of quickly surfacing: see blow-up .
Helmet divers in history and literature
The use of helmet diving equipment was of great importance among Aegean sponge divers and pearl divers in the Pacific since the 19th century . Inadequate technology and insufficient knowledge of diving physics or diving medicine, for example regarding decompression, often led to the most serious accidents and an alarmingly large number of victims. Another contemporary treatment method was the literal “putting the person on ice”, which was hardly feasible on remote islands. The characteristic paralysis of helicopter divers who have had an accident have even found their way into the folk dances of the inhabitants of Greek sponge fishing centers such as Symi and Kalymnos .
1805 John Braithwaite conducted a salvage operation at the wreck of the same year ago with helmet diving equipment Weymouth sunken East Indiaman by Earl of Abergavenny.
The newly invented closed helmet diving equipment found greater use in mining operations and the subsequent demolition of the British battleship Royal George , which sank in 1782, off Spithead. The work at a depth of around 20 meters, started by royal pioneers in 1839, led to the development of basic working methods underwater. The “two-man principle” (“ buddy system”) of today's diving, for example, comes from the work at that time. The rescue work, in which 32 divers led by 5 officers were involved, ended after 6 years. Among other things, an admiral's sword was recovered. The wreck was then blown up, it was in a shipping route.
In the Baltic Sea of the 19th century, since the second half to the 1960s in greater numbers Stein Fischer in action, who recovered with the help of helmet diving equipment stones for the construction of piers and harbor fortifications from the Baltic reason.
A wide audience is best known for the Science Fiction - Roman 20000 miles under the seas of Jules Verne , whose main characters wander in autonomous helmet diving equipment on the sea floor. Less utopian for its time is an episode in Verne's lesser known novel Die Jangada , in which an actor climbs into the Amazon with a conventional helmet diving device without being trained for it.
From 1885, the American archaeologist Edward Herbert Thompson used helmet diving equipment to carry out underwater archaeological excavations in the Holy Well of Chichén Itzá . It is likely to be the first mission of this kind, which was used for professional archaeological work and not just for treasure recovery.
Between 1906 and 1911, the diver William Walker carried out work on the foundations of Winchester Cathedral with a helmet diving device and thus restored the stability of the building. It threatened to sink into the subsurface of peat and near-surface groundwater. Walker replaced the soft ground under the foundation with bags of cement. A monument near the cathedral commemorates this legendary mission.
Helmet divers also occasionally appear in Siegfried Lenz's work , for example in the novel Der Mann im Strom (1957), which is set in the Hamburg harbor diver milieu and was filmed with the participation of Hans Albers , and in the radio play The Night of the Diver .
At the beginning of the film In the Rush of the Deep , helmet diving has a brief retrospective, albeit fatal, appearance.
The film Men of Honor tells the story of the first black navy diver in the US Navy , Carl Brashear , in the 1950s.
Museum reception
In Wiener Heeresgeschichtlichen Museum is a completely preserved dipping system Siebe Gorman, consisting of the diving helmet, the suit with lead weights and the hand-operated air pump, issued. The system was used from 1910 by the Austro-Hungarian Navy for work under water.
literature
- Hermann Stelzner: diving technique - manual for divers / textbook for diver aspirants . Charles Coleman Publishing House, Lübeck 1943.
- Gert Augustinski: From the air bubble to the diving helmet. the history of the development of diving technology. 2nd edition, self-published, Petersberg 1994.
- Michael Jung: The manual for diving history S. Naglschmid, Stuttgart, 1999.
Web links
Individual evidence
- ^ Jung, Michael: With a Kreeft-suit in a swimming pool. In: Historical Diver, No. 33, Fall 2003. p. 23.
- ^ Army History Museum / Military History Institute (ed.): The Army History Museum in the Vienna Arsenal . Verlag Militaria , Vienna 2016, ISBN 978-3-902551-69-6 , p. 165