Ted Eldred | |
|---|---|
 Ted Eldred in 2003 with an example of the world's first commercially available, single hose scuba unit, which was released early in 1952. | |
| Born | Edward Francis Eldred December 16, 1920 Melbourne, Victoria, Australia |
| Died | August 2005 (aged 84) Yarck, Victoria, Australia |
Edward Francis Eldred (16 December 1920 to August 2005) was a pioneer of scuba diving in Australia. He invented Porpoise scuba gear.
Eldred was born in Melbourne in 1920. As a young man he lived by the sea near Sorrento on the Mornington Peninsula south of Melbourne. He started snorkelling as soon as mask, fins and snorkel were available, and wished that he could make or obtain some sort of free-swimming breathing set, until World War II intervened. After World War II in the late 1940s he designed a sport diving oxygen rebreather. Eldred said he had never dived with the Cousteau-Gagnan model of the Aqua Lung, but knew of its existence and its principle. The Aqua Lung was protected by patent and difficult to obtain in Australia. Siebe Gorman had the license to manufacture for Commonwealth countries and could not meet demands. When Eldred decided that rebreathers were not suitable for general sport use, he shifted his focus to developing the world's first single-hose open-circuit scuba set, both with tradename "Porpoise". [1] [2]
Eldred's initial efforts were to make an oxygen rebreather safe for sporting use. [3] [4] Pure oxygen used in early rebreathers causes CNS poisoning below 6 msw. Eldred reasoned that the rebreather should be designed to stop flowing oxygen when the diver descended below that depth. At a demonstration by the Flinders pier, on Western Port Bay, south east of Melbourne, a diver passed out because he failed to purge the system of air. This failure to purge had resulted in a nitrogen build up. Eldred realised at this point that he needed to turn his efforts toward open circuit compressed air breathing apparatus. He was accompanied on this demonstration by Bob Wallace-Mitchell, who would become his distributor.
The French-designed open circuit scuba, called the Aqua-Lung, was protected by US and international patents, so Eldred set about designing the Porpoise CA (a prototype), the world's first single hose regulator. [5] Eldred referred to the French model as the Gagnan Aqua Lung, as designer Émile Gagnan was the Frenchman who actually designed the device for Jacques Cousteau. This new design was superior to the Aqua-Lung, and did not violate any of the existing patents. Eldred's regulator was never patented as his business was too small for the expense. The first production model was designated the CA-1. (C A for compressed air, 1 for single cylinder) He began using an oxygen welding reduction valve for his prototype. His chief design effort was developing the demand valve which people now call the second stage. It was sold as a complete single cylinder, single hose scuba early in 1952. The cylinder was inverted so the diver could reach the innovative regulator mounted reserve. Only about a dozen of these exist and are now in the hands of scuba collectors. Eldred also made the CA-2, which was a double cylinder model. Only two CA-2 Porpoises are still known to exist. About three quarters of the Porpoises made were surface supplied 'hookah' units. The 'hookah' was the device which started the demise of the standard dress helmet diving equipment. The Porpoise single hose scuba found its initial international praise in Arthur C. Clarke's 1955 book Coast of Coral. [5] Clarke brought two French Mistrals to Australia, but set them aside when he was loaned two Porpoises for his Australian adventure by Eldred. They are illustrated in Clarke's book.
Eldred's company was called Breathing Appliances Pty Ltd and located at 70 Abbotsford St., North Melbourne. [1] His marketing was done by his friend Bob Wallace-Mitchell. [6] It was difficult for Wallace-Mitchell to market in those early days, as compressed air was not readily available. His first task was to locate a compressor with a sales point in each of the Australian capital cities. Once this was done, dealers could stock his scuba and refill the cylinders. In 1954 Eldred also created the Porpoise Universal, which had a high supply rate of over 300 liters per minute. The Universal used the same demand valve and was modular in design. The reduction valve was a balanced diaphragm type, which was modified to become a piston type. It became his flagship model. Eldred also made a cheaper model, called the Sportsman. The Sportsman was a very compact regulator with innovative features now found on regulators of today. It was made of plastic and had an unbalanced first stage. Market needs made this model necessary, but Eldred did not like it.
The Royal Australian Navy (RAN) supported Eldred's efforts and adopted the Porpoise Universal for military use. [5] The RAN became the first navy to be equipped with single hose scuba. Eldred's diving school was established by RAN Commander Maurice "Batts" Batterham, GM. [4] It was the first SCUBA diving school in Australia and the first in the world to teach with the single hose regulator — it was located at the Melbourne City Baths. [4] It was a course designed to promote the new Porpoise, but later other brands of scuba were also used. The school continued for about ten years, later sending its students to the newer Associated Divers Academy which taught at the YMCA. The Australian government was still sensitive about the attempted invasion by the Japanese. They supported the course by allowing Batterham to conduct it and they kept a record of those who attended. This gave them a conscription base should hostilities ever occur again.
In 1960 the French firm L'Air Liquide, which owned U.S. Divers Corp., and the patent to the Aqua-Lung, bought Eldred out, under threat of flooding his market with their products. [2] The Porpoise continued to be marketed under the name Australian Divers Spiro Pty. Ltd. Eldred worked for them for a time, but eventually left diving behind, discouraged by this experience. Later Australian Divers Spiro ceased production of all of the Porpoise models, but had to continue to supply the RAN because of an existing contract. The last Porpoise sold was the RAN variation of the Porpoise Universal in 1976. About 12,000 Porpoise units were produced, but only a few dozen of all models are known to exist today. The more common French Aqua-Lung was produced in far larger numbers, with 12,000 being made in a single month. Today the French design is considered obsolete, while the Australian design is made and used world wide.
Ted Eldred was recognised in later life, by the Historical Divers Society (South-East Asia Pacific), as the inventor of the first successful commercially produced single hose SCUBA. [2] Eldred made his last dive with his grandson Adam, at an event in Ted Eldred's honor. The single hose SCUBA is the type in use around the world today. Eldred was presented the first "Ted Eldred Award" for significant contributions to diving by the Historical Diving Society (SEAP). [2] When Eldred died, he did not have a single complete Porpoise left. The Historical Diving Society (SEAP), presented a working Porpoise to Eldred's son Tony, so that the family would have an example of Ted Eldred's achievements.
Ted Eldred died of cardiac arrest at his Yarck, Victoria country home, in August 2005. [1] He was survived by a son and a daughter. [7]
A scuba set, originally just scuba, is any breathing apparatus that is entirely carried by an underwater diver and provides the diver with breathing gas at the ambient pressure. Scuba is an anacronym for self-contained underwater breathing apparatus. Although strictly speaking the scuba set is only the diving equipment that is required for providing breathing gas to the diver, general usage includes the harness or rigging by which it is carried and those accessories which are integral parts of the harness and breathing apparatus assembly, such as a jacket or wing style buoyancy compensator and instruments mounted in a combined housing with the pressure gauge. In the looser sense, scuba set has been used to refer to all the diving equipment used by the scuba diver, though this would more commonly and accurately be termed scuba equipment or scuba gear. Scuba is overwhelmingly the most common underwater breathing system used by recreational divers and is also used in professional diving when it provides advantages, usually of mobility and range, over surface-supplied diving systems and is allowed by the relevant legislation and code of practice.
The timeline of underwater diving technology is a chronological list of notable events in the history of the development of underwater diving equipment. With the partial exception of breath-hold diving, the development of underwater diving capacity, scope, and popularity, has been closely linked to available technology, and the physiological constraints of the underwater environment.
Aqua-Lung was the first open-circuit, self-contained underwater breathing apparatus to achieve worldwide popularity and commercial success. This class of equipment is now commonly referred to as a twin-hose diving regulator, or demand valve. The Aqua-Lung was invented in France during the winter of 1942–1943 by two Frenchmen: engineer Émile Gagnan and Jacques Cousteau, who was a Naval Lieutenant. It allowed Cousteau and Gagnan to film and explore underwater more easily.
A diving cylinder or diving gas cylinder is a gas cylinder used to store and transport high pressure gas used in diving operations. This may be breathing gas used with a scuba set, in which case the cylinder may also be referred to as a scuba cylinder, scuba tank or diving tank. When used for an emergency gas supply for surface supplied diving or scuba, it may be referred to as a bailout cylinder or bailout bottle. It may also be used for surface-supplied diving or as decompression gas. A diving cylinder may also be used to supply inflation gas for a dry suit or buoyancy compensator. Cylinders provide gas to the diver through the demand valve of a diving regulator or the breathing loop of a diving rebreather.
A diving regulator or underwater diving regulator is a pressure regulator that controls the pressure of breathing gas for underwater diving. The most commonly recognised application is to reduce pressurized breathing gas to ambient pressure and deliver it to the diver, but there are also other types of gas pressure regulator used for diving applications. The gas may be air or one of a variety of specially blended breathing gases. The gas may be supplied from a scuba cylinder carried by the diver, in which case it is called a scuba regulator, or via a hose from a compressor or high-pressure storage cylinders at the surface in surface-supplied diving. A gas pressure regulator has one or more valves in series which reduce pressure from the source, and use the downstream pressure as feedback to control the delivered pressure, or the upstream pressure as feedback to prevent excessive flow rates, lowering the pressure at each stage.
Scuba diving is a mode of underwater diving whereby divers use breathing equipment that is completely independent of a surface breathing gas supply, and therefore has a limited but variable endurance. The name scuba is an anacronym for "Self-Contained Underwater Breathing Apparatus" and was coined by Christian J. Lambertsen in a patent submitted in 1952. Scuba divers carry their own source of breathing gas, usually compressed air, affording them greater independence and movement than surface-supplied divers, and more time underwater than free divers. Although the use of compressed air is common, a gas blend with a higher oxygen content, known as enriched air or nitrox, has become popular due to the reduced nitrogen intake during long or repetitive dives. Also, breathing gas diluted with helium may be used to reduce the effects of nitrogen narcosis during deeper dives.
Submarine Products Ltd (1959−1990) was a diving gear manufacturer, with a factory in Hexham in Northumberland, England. It was founded in 1959 by Lieutenant-Commander Hugh Oswell.
Porpoise is a tradename for scuba developed by Ted Eldred in Australia and made there from the late 1940s onwards. The first Porpoise was a closed circuit oxygen rebreather, and the following models were all single hose open circuit regulators.
Vintage scuba is scuba equipment dating from 1975 and earlier, and the practice of diving using such equipment.
Aqua Lung International is a large and well-known firm which makes scuba and other self-contained breathing apparatus, and other diving equipment. It produced the Aqua-Lung line of regulators, like the CG45 (1945) and the Mistral (1955), among others. Until 2016, the company was a division of Air Liquide since its foundation in 1946. The company was sold to Montagu Private Equity in 2016.
The Lambertsen Amphibious Respiratory Unit (LARU) is an early model of closed circuit oxygen rebreather used by military frogmen. Christian J. Lambertsen designed a series of them in the US in 1940 and in 1944.
Scuba gas management is the aspect of scuba diving which includes the gas planning, blending, filling, analysing, marking, storage, and transportation of gas cylinders for a dive, the monitoring and switching of breathing gases during a dive, efficient and correct use of the gas, and the provision of emergency gas to another member of the dive team. The primary aim is to ensure that everyone has enough to breathe of a gas suitable for the current depth at all times, and is aware of the gas mixture in use and its effect on decompression obligations, nitrogen narcosis, and oxygen toxicity risk. Some of these functions may be delegated to others, such as the filling of cylinders, or transportation to the dive site, but others are the direct responsibility of the diver using the gas.
Scuba skills are skills required to dive safely using self-contained underwater breathing apparatus, known as a scuba set. Most of these skills are relevant to both open-circuit scuba and rebreather scuba, and many also apply to surface-supplied diving. Some scuba skills, which are critical to divers' safety, may require more practice than standard recreational training provides to achieve reliable competence.
The history of underwater diving starts with freediving as a widespread means of hunting and gathering, both for food and other valuable resources such as pearls and coral. By classical Greek and Roman times commercial applications such as sponge diving and marine salvage were established. Military diving also has a long history, going back at least as far as the Peloponnesian War, with recreational and sporting applications being a recent development. Technological development in ambient pressure diving started with stone weights (skandalopetra) for fast descent. In the 16th and 17th centuries diving bells became functionally useful when a renewable supply of air could be provided to the diver at depth, and progressed to surface-supplied diving helmets—in effect miniature diving bells covering the diver's head and supplied with compressed air by manually operated pumps—which were improved by attaching a waterproof suit to the helmet and in the early 19th century became the standard diving dress.
The history of scuba diving is closely linked with the history of the equipment. By the turn of the twentieth century, two basic architectures for underwater breathing apparatus had been pioneered; open-circuit surface supplied equipment where the diver's exhaled gas is vented directly into the water, and closed-circuit breathing apparatus where the diver's carbon dioxide is filtered from the exhaled breathing gas, which is then recirculated, and more gas added to replenish the oxygen content. Closed circuit equipment was more easily adapted to scuba in the absence of reliable, portable, and economical high pressure gas storage vessels. By the mid-twentieth century, high pressure cylinders were available and two systems for scuba had emerged: open-circuit scuba where the diver's exhaled breath is vented directly into the water, and closed-circuit scuba where the carbon dioxide is removed from the diver's exhaled breath which has oxygen added and is recirculated. Oxygen rebreathers are severely depth limited due to oxygen toxicity risk, which increases with depth, and the available systems for mixed gas rebreathers were fairly bulky and designed for use with diving helmets. The first commercially practical scuba rebreather was designed and built by the diving engineer Henry Fleuss in 1878, while working for Siebe Gorman in London. His self contained breathing apparatus consisted of a rubber mask connected to a breathing bag, with an estimated 50–60% oxygen supplied from a copper tank and carbon dioxide scrubbed by passing it through a bundle of rope yarn soaked in a solution of caustic potash. During the 1930s and all through World War II, the British, Italians and Germans developed and extensively used oxygen rebreathers to equip the first frogmen. In the U.S. Major Christian J. Lambertsen invented a free-swimming oxygen rebreather. In 1952 he patented a modification of his apparatus, this time named SCUBA, an acronym for "self-contained underwater breathing apparatus," which became the generic English word for autonomous breathing equipment for diving, and later for the activity using the equipment. After World War II, military frogmen continued to use rebreathers since they do not make bubbles which would give away the presence of the divers. The high percentage of oxygen used by these early rebreather systems limited the depth at which they could be used due to the risk of convulsions caused by acute oxygen toxicity.
A Diving rebreather is an underwater breathing apparatus that absorbs the carbon dioxide of a diver's exhaled breath to permit the rebreathing (recycling) of the substantially unused oxygen content, and unused inert content when present, of each breath. Oxygen is added to replenish the amount metabolised by the diver. This differs from open-circuit breathing apparatus, where the exhaled gas is discharged directly into the environment. The purpose is to extend the breathing endurance of a limited gas supply, and, for covert military use by frogmen or observation of underwater life, to eliminate the bubbles produced by an open circuit system. A diving rebreather is generally understood to be a portable unit carried by the user, and is therefore a type of self-contained underwater breathing apparatus (scuba). A semi-closed rebreather carried by the diver may also be known as a gas extender. The same technology on a submersible or surface installation is more likely to be referred to as a life-support system.
The mechanism of diving regulators is the arrangement of components and function of gas pressure regulators used in the systems which supply breathing gases for underwater diving. Both free-flow and demand regulators use mechanical feedback of the downstream pressure to control the opening of a valve which controls gas flow from the upstream, high-pressure side, to the downstream, low-pressure side of each stage. Flow capacity must be sufficient to allow the downstream pressure to be maintained at maximum demand, and sensitivity must be appropriate to deliver maximum required flow rate with a small variation in downstream pressure, and for a large variation in supply pressure, without instability of flow. Open circuit scuba regulators must also deliver against a variable ambient pressure. They must be robust and reliable, as they are life-support equipment which must function in the relatively hostile seawater environment, and the human interface must be comfortable over periods of several hours.
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