Porpoise is a

tradename A trade name, trading name, or business name, is a pseudonym used by companies that do not operate under their registered company name. The term for this type of alternative name is a "fictitious" business name. Registering the fictitious name w ...

for

scuba Scuba may refer to: * Scuba diving ** Scuba set, the equipment used for scuba (Self-Contained Underwater Breathing Apparatus) diving * Scuba, an in-memory database developed by Facebook * Submillimetre Common-User Bolometer Array, either of two in ...

developed by

Ted Eldred Edward Francis Eldred (16 December 1920 to August 2005) was a pioneer of scuba diving in Australia. He invented Porpoise scuba gear. Early years Eldred was born in Melbourne in 1920. As a young man he lived by the sea near Sorrento on the Mor ...

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.

Rebreather

The Porpoise oxygen

rebreather A rebreather is a breathing apparatus that absorbs the carbon dioxide of a user's breathing, exhaled breath to permit the rebreathing (recycling) of the substantially unused oxygen content, and unused inert content when present, of each breath. ...

was developed by

in the late 1940s and early 1950s. Some were made and used for sport diving, but they did not go into full production. It was worn on the back without a casing. The bag was between the canister and valve assembly and the diver's back. It had two wide breathing tubes running to a mouthpiece, which had a shutoff valve to keep water out when it was not in the mouth. It appeared in three versions: MK1, MK2, MK3. It had a special valve that both breathing tubes ran through that was activated by surrounding pressure; when the diver went deeper than was safe for pure oxygen it restricted (not stopped) the supply of breathing gas, to warn the diver to go to shallower depth. (Before open-circuit scuba was readily available in Australia, many Australian sport divers used war-surplus

Siebe Gorman Salvus The Siebe Gorman Salvus is a light oxygen rebreather for industrial use (including by firemen and in coalmine rescue) or in shallow diving. Its duration on a filling is 30 to 40 minutes. It was very common in Britain during World War II and for ...

rebteathers.)

Single-hose open-circuit scuba regulator

This was the first single-hose open-circuit

made in the world.

Melbourne Melbourne ( ; Boonwurrung/Woiwurrung: ''Narrm'' or ''Naarm'') is the capital and most populous city of the Australian state of Victoria, and the second-most populous city in both Australia and Oceania. Its name generally refers to a met ...

in Australia started designing it in 1948 to "design around" the Cousteau-Gagnan aqua-lung patent, and to get rid of air supply restrictions that affected early Cousteau-Gagnan-type aqua-lungs. He started making it commercially in 1952. The

Royal Australian Navy The Royal Australian Navy (RAN) is the principal naval force of the Australian Defence Force (ADF). The professional head of the RAN is Chief of Navy (CN) Vice Admiral Mark Hammond AM, RAN. CN is also jointly responsible to the Minister of ...

adopted it. It was the origin of single-hose scuba regulators. It was much used by Australian scuba divers. The picture shows the CA-1, a set with one

cylinder A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base. A cylinder may also be defined as an infin ...

with its valve at the bottom, strapped directly to the back with rucksack-type straps without backpack plate or buoyancy aid, with a single-hose regulator-mouthpiece which could be strapped in. The tank was inverted so that the diver could reach the regulator mounted reserve handle. The head strap was intended to keep the demand valve from falling well below the diver, if dropped from the mouth. The high-pressure regulator screwed into the side of the

valve like welding equipment of today; there was no

A-clamp 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 scu ...

. Versions of it were made for the Australian Navy until 1976, and the last one known to be sold to the public was sold in that year. About 12,000 Porpoise units of all models were produced. About 50 Porpoises still exist. Only a few of these early models are known today, the rarest being the CA-2, made for use with two tanks.

References

*Historical Diving Times No.36 Summer 2005 *Historical Diving Times No.38 Winter 2006

External links

Link to page with images
about Ted Eldred's oxygen rebreather {{DEFAULTSORT:Porpoise (Make Of Scuba Gear) Underwater breathing apparatus Rebreathers Diving equipment manufacturers

Rebreather

Single-hose open-circuit scuba regulator

See also

References

External links