Mixed Gas and Rebreathers

SAFETY WARNING

NEVER, EVER DIVE A HELMET OR ANY EQUIPMENT UNLESS YOU ARE ABSOLUTELY SURE IT IS GENUINE AND IN PROPER WORKING CONDITION. Replica helmets are not designed or built for actual use. Attempting to dive a replica helmet could result in serious injury or death. Only dive after you have received the proper training.

Mixed Gas and DESCO

In 1935 Max Nohl had his sights set on salvaging the cargo of the Prohibition rum runner John Dwight. At this time Max made his connection to John D. Craig. John Craig owned the film rights to the sunken Liner RMS Lusitania. Nohl had already been working on diving equipment to work at the Lusitania’s depth. Additional support equipment would need to be designed and built for the project. Nohl using the suit design from his MIT thesis as a starting point began experimentation on building the necessary gear. Another Milwaukee native, Jack Browne came on the scene at this time. Browne’s name first appears on the 50 foot test dive in the fall of 1937.

The third man in the story was Dr. Edgar End. Dr. End was a graduate of the Marquette University Medical School and was a practicing physician. He served as Assistant Clinical Professor of Environmental Medicine at Marquette. In this capacity he was studying the effects of Caisson Disease on Milwaukee tunnel workers. In April 1937 Max Nohl contacted Dr. End about his development of Helium/ Oxygen decompression tables. Dr. End suggested using the recompression chamber in the basement of the Milwaukee County Hospital to test their theories. Their collaboration moved the development of the new equipment and the necessary background knowledge forward.

Browne and Nohl worked together on the design of a new type of lightweight, self-contained diving suit. At the same time they worked with Dr. End to explore the promising possibility of preventing nitrogen narcosis by having the diver breathe a mixture of helium and oxygen rather than air.

On December 1, 1937 in Lake Michigan, Max Nohl succeeded in diving to a depth of 420 feet, thereby breaking a depth record which had been held by a U.S. Navy diver Frank Crilley, since 1915. Nohl accomplished this feat using DESCO's new diving equipment and breathing a heliox mixture prescribed by Dr. End. Ironically as war neared in Europe the British Admiralty began placing more and more restrictions on John Craig’s expedition so it was finally called off. The experiences of designing, constructing, and testing the equipment for the Lusitania expedition would pay large dividends in the near future.

Concurrently the U.S. Navy, under Dr. Albert Behnke and Cmdr Swede Momsen, was developing the equipment and techniques the that would be needed by military divers. The opportunity to test the techniques and equipment came when USS Squalus sank in 1939. The successful recovery of the Squalus proved the feasibility of deep mixed gas diving to the military and civilian ranks.

The outbreak of war shifted DESCO's focus from experimental diving to standard diving equipment production. World War II brought large Navy contracts for diving equipment to DESCO. The company’s research and development roots were not overlooked by the government. DESCO was contracted by the Office of Strategic Services (forerunner of the CIA) to design and build a compact oxygen rebreather. The result was the DESCO B-Lung. This unit, for the first time, permitted divers to swim freely under the surface, in the manner of SCUBA divers today, but without producing bubbles, which might disclose their position. Other projects included the Browne Utility Mixed Gas Helmet which morphed into the Buie Mixed Gas Helmet.

DESCO Helium Recirculating Helmets

U. S. Navy Helium Helmet

The U.S. Navy Helium Helmet is a offshoot of the USN Mark V Diving Helmet. The air inlet and communication elbows are moved up to allow for a canister attachment to the back of the bonnet. The Spitcock is deleted and the helmet lock is relocated to that position. On war years Helium helmets the exhaust tube running over the top of the bonnet terminated in a perforated bulb like the banana exhaust on the Mark V.

In the early 1950's a secondary double exhaust was installed to prevent leak back of water into the helmet. The scrubbing medium being used during the war was shell natron. It reacted with salt water and produced Chlorine gas. A accident of this kind would lead to severe injury and often death to the diver. Later on the shell natron was replaced with Baralyme which was safer. Water intrusion could still create problems with the Baralyme as it would reduce the effectiveness.

Early HEO2 with bulbous tube end. Late HEO2 with secondary double exhaust valve.

Model 100:

We don't have any blueprints or patterns from the Model 100 Helmet. It did appear in the 1946 catalog. the text read;

Browne Self-Contained Suit

Model 100

Cat. No. 29132

This model is similar in design and operation to the Model 106, with the exception of the breathing apparatus.

In this suit the diver carries both the oxygen cylinder and canister on his back. In place of a mouthpiece, the diver holds his face into a mask which directs the circulation of air through the canister. Diving depths and time limits with this model are comparable to the Model 106.

Weight 135lbs.

Standard size only.

Model 106:

We don't have any blueprints or patterns from the Model 106 Helmet. It did appear in the 1946 catalog. the text read;

Browne Self-Contained Suit

Model 106

Cat. No. 29133

This portable suit was especially designed for light salvage and inspection work. It is particularly adaptable to commercial divers who wish to make inspections or short salvage jobs where it would not pay to haul heavy equipment to the location. The Browne two piece dress which joins at the waist is used to facilitate handling and dressing. No breastplate is used. The diver carries oxygen cylinders compressed to 2000 pounds on his back, while the combined canister and chest weight hang on the diver's chest. The control valve hangs conveniently at the diver's waist.

The mouthpiece which the diver grasps lightly in his mouth is for breathing. many divers prefer this breathing system. this suit has been used for three hours in 20 feet of water and to 60 feet for 1 hour when pure oxygen is used. Short dives may be made to over 120 feet if the diver uses compressed air.

The helmet is constructed of spun Copper heavily coated with Tin and all fittings, including those on the suit, are of polished cast Brass. Windows are of clear, durable plastic. The case holding the oxygen cylinders is metal. Photos show the diver with combination telephone and lifeline cable. Dresses are supplied in light or heavy weight and in sizes A, B, and C.

Weight 135lbs. complete

Buie Diving Helmet

Lieutenant E. D. Buie was assigned to the US Navy Mine Disposal Unit during WW II. He approached DESCO about developing a non-magnetic helmet for the MDU. Working with Jack Browne they designed a lightweight low volume helmet with mixed gas capability.

Early Buie Helium Helmet

We refer to this helmet as a "Early" Buie helmet because the production Buie helmets had the faceted window as opposed to the curved one. The curved window tended to distort the diver's vision underwater. It does have the Buie canister assembly and exhaust valve as on the later helmets.

Late Buie Helium Helmet

Browne Utility Helium Helmet

Although we have no blueprints or documentation for this helmet we believe it was a follow on development of the Browne Utility Helmet. It may have been developed concurrently with the Buie or as a precursor. It differs from the Buie in that the canister is integrated into the helmet, not removable. The basic exhaust design is similar but the Buie utilizes standard Mark V parts instead of the parts specific to this helmet. The lock mechanism is also different.

DESCO Rebreathers

DESCO began producing equipment for the U.S. Navy in 1942 to support the war effort. The Office of Strategic Services (forerunner to the CIA) needed rebreathers for covert operations. DESCO was contracted to design and produce the needed units. After that contract was completed subsequent units were sold to the Navy. With the end of WW II DESCO applied the technology to commercial and sport diving. SCUBA was still a few years away from wide acceptance. To supplement the commercial equipment business DESCO also marketed a line of sporting goods. The A-lung was targeted to this market segment. It was small and simple to use. The B-lung was the unit that DESCO developed during the war and was aimed at the commercial diver. The C-lung was a DESCO lightweight suit fitted with a heavy duty rebreather. In the late 40's and early 50's a fatal flaw in rebreathers surfaced. The breathing of pure oxygen under pressure caused a buildup of oxygen in the body actually poisoning the user. Several accidents caused manufacturers to reconsider the use of rebreathers by amateurs. This and the emergence of SCUBA compressed air tank diving spelled the end of production of rebreathers for sport use at that time. Today new technology has allowed rebreathers to make a comeback by onboard computers monitor the system thus reducing the risks.

Here is a look at the DESCO rebreathers.

The DESCO A-Lung

Also known as the Adventurer, and the Sportster Lung. This unit was designed in the early 1950's. It was a simpler, more compact design than the B-Lung. The unit evolved during its short run. Early units had a canvas breather bag, while later units had a vinyl bag. The A-Lungs were only produced for a few years in the mid-50's.

Diagrams of the A Lung models

To download a copy of the A Lung Instruction Sheet click here .

Notice: These instructions are provided for informational purposes only. Due to the age of this equipment, and the inherent danger in the use of the old rebreathers, DESCO strongly recommends that these units are never used for diving.

The DESCO B-Lung

Also known as the Buccaneer Lung. This is the unit first developed for the OSS and U.S. Navy during WWII. The first units used a oval mask with a nose bump out. Later units were fitted with a modified Jack Browne mask. B-Lungs were produced until the early 1960's. On the 1960 DESCO pricelist the B-Lung cost $205.00.

Above photos show a early B-Lung with the oval mask and a nose bump out.

Below photos show a later unit equipped with the Jack Browne triangular mask.

To download a copy of the Browne Lung Instruction Sheet click here .

To download a copy of the Buccaneer Lung Instruction Sheet click here .

The DESCO C-Lung

The C-Lung is a DESCO Lightweight Suit mated to a rebreather unit on the diver's back. This configuration allowed the diver to remain completely dry.

Literature pertaining to the DESCO Rebreathers.

Lindbergh - Hammar Associates

PURA 787 CO2 Removal System

In 1969 DESCO partnered with Lindbergh - Hammar Associates to produce and market a lightweight Helium helmet using the DESCO Air Hat and LHA PURA CO2 Scrubber system. Jon Lindbergh was the second child of Charles and Anne Morrow Lindbergh.

The PURA system was a electrically powered, turbine pressurized unit which circulated mixed gas through the helmet and back to a CO2 absorption canister. The larger LHA PURA system used for recompression chambers, underwater habitats, personnel transfer capsules, and medical hyperbaric chambers. The helmet unit was mounted to a backpack. It was based on the larger unit's technology.

Unlike the U.S. Navy's standard Helium helmet, based on the Mark V, which used a venturi system to move the gas mix, the LHA system used a electrically powered turbine to force the gas mix through the system. A venturi system requires new gas to be pumped into the system for recirculation and this results in gas loss through the exhaust valve.

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Thomas B Fifield and Jon Lindbergh display the Air Hat/PURA unit.

A brochure for the PURA 787/ DESCO Air Hat.

The PURA unit for chamber and habitat use. It was available in a Aluminum or Bronze housing.

The DC power supply 787-MPXA.

The DESCO ad sheet for the PURA 787-M9

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