Technical Information

Warnings and Cautionary Notes

Non safety related issues which may affect the operation or longevity of your DESCO product. ALL SAFETY related warnings are listed on the Safety Page

Powder Coating soldered diving helmets.

Over the years we have had to repair more than one DESCO Air Hat that somebody attempted to powder coat. Helmets made by DESCO Corporation be it Air Hat or Classic Style are made of Copper and Brass components which are soft soldered with a 50/50 Lead Tin solder alloy. The melting temperature of 50/50 solder is in a range from 365–419 °F - 185–215 °C.

The thermoset or thermoplastic coating when sprayed onto the part adheres to it by electrostatic charge. Once the part is sprayed it must be heated to melt and cure the coating. The typical coating requires heating to 390°F - 200°C for 10 minutes in order to cure. This temperature falls right in the middle of the range to melt soft solder. Ten minutes is ample time to soften and/or melt out the largest solder joints on a helmet.

Once a helmet is desoldered in this manner it must be totally disassembled, the old solder cleaned up, and the helmet completely resoldered. No solder joint can be left "as is" since it is not possible to visually verify the integrity of an affected joint.

Powder coating miscellaneous parts of the helmet doesn't work either. The coating is by necessity fairly thick. The additional thickness of the coating will put parts outside their dimensional requirements and they will not fit or will not function as designed.

The snout, tail, and speaker ring came off the helmet. 90% of the solder was gone from the shell to neckring joint on this Air Hat.

The powder coating gets into areas where it can't be left. The clamps and bolts were both coated so now they won't fit together. Having either coated would have made assembly impossible. The valve handle will not fit onto the valve stem. The hole could be re-broached but it is likely the coating would crack and chip, defeating the purpose.

DESCO Air Hat Tech Specs & Notes:

The complete DESCO Air Hat Manual is available for download on the Downloads Page.

Threading Specifications;

Air Inlet (double elbow) 1/4" NPT

Non-Return Valve (inlet, umbilical) 9/16"-18 Oxygen (CGA 022 B size)

Non-Return Valve (outlet, helmet) 1/4" NPT

Window Screw #10-32 NF

Video Block 3/8"- 16 NC

Double Exhaust Valve Retaining Screw #6-32 NC

Clamp Bolt Threading 1/4"-20 NC

Lock Bolt Threading 1/4"-20 NC

Clamp & Lock Nut 1/4"-20 NC, Self Locking

Communications Pigtail Port 1/8" NPT

Minimum air flow rate for DESCO Air Hat = 6cfm @ 100psi over bottom pressure.

Microphone/Speaker is held in place with 3M® VHB Double Sided Foam tape.

Inside Air Elbow and pigtail bulkhead fitting is epoxied in place with 10 minute two part epoxy.

Neck Ring Gasket Adhesive:

The neck ring gasket in the DESCO Air Hat is cemented in place using "disk adhesive". This adhesive is used to attach paper sanding disks to the foam pads on DA sanders. This adhesive allows for easy removal and replacement of the neck ring gasket. More aggressive adhesives will make removal of the neck ring gasket difficult and almost impossible to achieve without destroying the gasket. The most common brands are 3M™ Feathering Disc Adhesive, Norton No. 10 Disc Adhesive, and Carborundum Disc Cement. One or more of these brands are available at auto body supply stores.

Air Distributor and Lambswool:

Lambswool is a coarse fiber material that does not compress to the point where it would choke airflow. THERE IS NO SUBSTITUTE FOR LAMBSWOOL. Cotton and other similar materials will compress to a point where it can impede airflow. Never substitute another material in the air distributor. Lambs wool is available in Drug Stores, and the health products aisle in most department and grocery stores. The Lambs wool will also act as a filter in the incoming air.

WARNING: Teflon® Tape

Teflon® tape should never be used on any part of the Air Hat. The possibility exists for pieces of Teflon® tape to enter the air delivery system and cause a blockage. Use plumbers putty to seal Non-return Valves to the Air Inlet Elbows.

Air Control Valve Stem Adapters

When the valve handle on the Air Hat was changed a few years ago it was decided to do away with the extender on the adapter. The skirt on the new valve handle offers protection to the valve stem. Air hats using the old style handle will still benefit from the adapter with the extender. The parts list has been amended to list the adapter in two versions. Part number 61132 is the stock adapter, while 61132E is the adapter with the extender.

Air Hat with old valve handle. Air Hat with new valve handle. Air Control Valve with adapter. Air Control Valve with extender adapter.

61132 Adapter 61132E Adapter ACV adapters

Chemical Compatibility with materials used on the DESCO Air Hat

If the DESCO Air Hat is to be used in any fluid other than water the user must determine the suitability of the Air hats seals in relation the fluid. Compatibility charts are available online from several sources. Type "material compatibility" into your search engine.

Exhaust Valve Flapper Disk is Natural Rubber

Neck Seal O-Ring is Polyisoprene (Natural Rubber )

Window Gasket is Neoprene.

Double Exhaust Valve O-Ring is Buna 70

Clamp & Lock Washers are Nylon 101

Video Block Washer is SBR Rubber

Question about alignment of the Air Control Valve in the Air Hat snout

Several people over the last few years have called or e-mailed with concerns about the angle of the Air Control Valve in relation to the face of the snout. The angle is caused by the draft in the casting which is necessary to remove the pattern from the mold. (see http://en.wikipedia.org/wiki/Draft_(engineering)). When they are received from the foundry the raw casting is sanded inside and out. The front face is milled to provide a clean level surface for the window gasket. The snout is machined so its axis are all parallel and perpendicular with the rest of the helmet components. There is a small degree of draft on the inner and outer surfaces of the casting and the result is an accumulation of the draft from both sides which is visible under the valve handle. The draft angle has to be accounted for when the exhaust port hole is drilled as the exhaust base must rest flat on the face for soldering. This is done during the threading of the exhaust hole.

Angle of the Air Control Valve on the Air Hat.

Draft in the snout casting.

Aligning the snout in the fixture.

Drilling the mounting hole and relief.

The fixture holds the snout front and side perpendicular to the drill.

To date this angle has not been a safety or functionality issue. It is a aesthetic issue only. It would be possible to make the snout straight but at significant additional cost.

1. The casting could be machined to be straight but that would entail changing the pattern to add material which would later be machined off.

2. The casting process could be changed to investment casting but the per part price would jump significantly.

DESCO's philosophy has always been safety first, function second, cost/value third, then aesthetics a distant fourth. The ACV angle has always been there but it became noticeable with the introduction of the skirted valve handle. The skirt is there to reduce the snagging hazard posed by the valve handle sticking out. A safety consideration accentuated a aesthetic consideration, safety won.

U.S. Navy Mark V Helmet:

The DESCO U.S. Navy Mark V Diving Helmet has been in continuous production since 1942. It conforms to the Bureau of Ships drawings which we still have in our files. Three minor changes have been made in the 61 year production run but the basic helmet design has remained constant.

The helmet shell is heavy spun copper fitted with bronze castings. All unplated bronze parts are high polished. Standard finish is tin plated (per US Navy Specifications) but the helmet can be ordered polished if desired. Breastplate fits dresses with a U.S. Navy style collar only.

The only material change has been to replace glass windows with Acrylic. This change was approved by the U.S. Navy as the Acrylic windows offered more safety and economy.

Pre 1945 DESCO Mark V Helmets had a football shaped nametag marked "Diving Equipment and Salvage Co. Inc." which was a different shape than called for in BuShips drawings. When the company name changed to Diving Equipment and Supply Co. in late 1945 the tag was changed to an oval shape to conform to the BuShips drawings.

During the war subcontractors supplied parts and sub assemblies to speed war production. Mark V manufacturers (DESCO, Morse, Schrader, and Miller Dunn) used exhaust valve assemblies made by Batteryless Telephone Equipment Company. After the war these parts were made in house at DESCO for our helmets.

There is one additional difference between a DESCO Mark V Helmet you can purchase today and one from 1942. In 1962 the design of the Non-Return valve was changed by the USN to utilize a cartridge check valve instead of the plunger and seat style of the original design.

Threading Specifications;

The U.S. Navy Mark V Helmet Air Inlet Elbow threading is 1 1/16" - 17 (Submarine Thread).

The U.S. Navy Mark V Helmet communications elbow threading is 1.715 - 11.

The U.S. Navy Mark V Helmet Front Door Toggle Bolt threading is 1/2" - 13 NC.

The U.S. Navy Mark V Helmet Window Guard Screws are #8 - 32 NC.

The U.S. Navy Mark V Helmet Breastplate Stud threading is 1/2" - 12 NS.

The U.S. Navy Mark V Helmet Neck Ring Threads (interrupted) 9 13/64" - 6 NS

The U.S. Navy Mark V Helmet head opening in Neck Ring 8 9/16"

U.S. Navy Mark V Helium Helmet:

This is the standard U.S. Navy Helium/Oxygen Mixed Gas Helmet based on the standard Mark V Helmet. The main feature of this helmet is the canister mounted on the rear of the helmet and a venturi system allowing for recirculation of breathing gas to conserve Helium. The canister was filled with a scrubbing agent to remove Carbon Dioxide from the breathing mix.

The breastplate is the same as a normal Mark V except the lock assembly is located in front in place of the spitcock. All other parts are the same as a standard Mark V except for the omission of the spitcock valve, and the addition of a extra communications elbow which the Navy used to connect electrically heated underwear to a power source.

The canister can be removed and with the canister elbows capped the helmet can function as a normal Mark V. Standard finish is Tin plate but the helmet is also available polished. Shipping weight with canister approximately 93 lbs.

Helium Helmet Exhaust Valve Configurations.

The U.S. Navy Mark V Helium Helmet has two versions. The early version (pre 1950's) has a exhaust tube extending to the upper back terminating in a bulb with holes like the standard Navy exhaust (banana). It was found that water could seep back through the exhaust valve and mix with the CO2 scrubbing agent and create Chlorine gas. This gas would be inhaled by the diver and result in serious injury or death. The design was changed in the early 1950's. Helium helmets from this point on incorporated a double exhaust valve in place of the bulbous end.

Threading Specifications;

The common parts between the Mark V Helmet and the Helium Helmet are identical (see Mark V specs).

High Pressure Nozzle threading : 3/4"-16

Discharge Nozzle threading: 3/4"-16

Canister Elbow threading: 2 3/4"-8

DESCO Commercial Helmet

These heavy Commercial helmets use the standard commercial pattern breastplate and top shell. The DESCO Commercial Helmet is available in three or four light configuration.

This helmet is similar in material and construction to the U.S. Navy Mark V but makes use of a simpler, although equally rugged design. Breastplate will fit dresses with a commercial collar only. The front faceplate is a screw in type with a guard and turn knobs. Side windows are oval increasing field of vision. The side windows may be mounted vertically to increase vision on that axis.

Standard fittings included with Four Light Commercial Helmet:

Double spring, adjustable tension, automatic exhaust valve with exterior star-wheel, interior chin button, and banana tube to exhaust air to the rear of the helmet.
Non-return valve with standard submarine threads.
Breastplate eyelets for hose and lifeline attachments.
Breastplate and faceplate gaskets.
Spitcock
Telephone cup
Transceiver
Telephone Gooseneck
Spring Lock
Front window is circular and uses a screw in type faceplate.
Side windows are oval and are mounted horizontally (can be mounted vertically by request).
Oval top window.

Approximate shipping weight 58 lbs.

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Standard fittings included with Three Light Commercial helmet:

Double spring, adjustable tension, automatic exhaust valve with exterior star-wheel, interior chin button, and banana tube to exhaust air to the rear of the helmet.
Non-return valve with standard submarine threads.
Breastplate eyelets for hose and lifeline attachments.
Breastplate and faceplate gaskets.
Spring Lock
Front window is circular and uses a screw in type faceplate.
Side windows are oval and are mounted horizontally (can be mounted vertically by request).

Options:

Spitcock
Telephone cup
Transceiver
Telephone Gooseneck

Approximate shipping weight 54 lbs.

Threading Specifications;

Air Inlet Elbow threading is 1 1/16" - 17 (Submarine Thread).

Front faceplate threading is 5 13/16" - 20 NF

Communications elbow threading is 1.715 - 11.

Window Guard Screws are #8 - 32 NC.

Breastplate Stud threading is 1/2" - 12 NS.

Neck Ring Threads (interrupted) 9 13/64" - 6 NS

Head opening in Neck Ring 8 9/16"

DESCO Lightweight Helmets Sponge, Abalone, Agar, and Browne Commercial

The DESCO "Lightweight" series of helmets are of the same materials and constructions as their heavier brothers. They have considerably less weight and volume than the "heavies". All share the Lightweight (Sponge) pattern breastplate and top shell, with modifications to suit varying customer and market demands.

Options for lightweight helmets:

Communications system Cat. No. 21300
Spitcock P/N 29035
Breastplate loops P/N 21149 (standard on Abalone)
Available in Tin plated or polished finish (except Browne Commercial is plated only).

Sponge Divers Helmet

The Sponge Divers Helmet features a screw in faceplate. The side and top windows are secured with rings threaded into the bases and are without guards. The exhaust is a non-adjustable head butt type. The non-return valve is integrated into the air inlet elbow. Breastplate loops and communications is optional. Shipping weight is approximately 39 lbs.

Threading Specifications;

Air Inlet Elbow threading is 1 1/16" - 17 (Submarine Thread).

Front faceplate threading is 5 13/16" - 20

Side window frame threading is 4 5/8" - 20

Top window frame threading is 4 5/16' - 20

Exhaust valve cover threading is 1 3/4" - 16

Exhaust valve cover lock screw threading is #8 - 32 NC

Neck Ring Threads (interrupted) is 8 15/16" - 6

Head opening in Neck Ring is 8 3/8"

Breastplate stud & wing nut threading is 7/16" - 14

Abalone Divers Helmet

The Abalone Divers Helmet features a Mark V style double spring adjustable tension exhaust valve. All windows have guards secured by screws. Breastplate loops are standard. The non-return valve is integrated into the air inlet elbow. Communications is optional. Shipping weight approximately 39 lbs.

Threading Specifications;

Air Inlet Elbow threading is 1 1/16" - 17 (Submarine Thread).

Front faceplate threading is 5 13/16" - 20

Window Guard Screws are #8 - 32 NC.

Neck Ring Threads (interrupted) is 8 15/16" - 6

Head opening in Neck Ring is 8 3/8"

Breastplate stud & wing nut threading is 7/16" - 14

Agar Divers Helmet

The Agar Divers Helmet features a single spring adjustable tension head butt exhaust valve with a downward extending vent tube. Windows are secured by Abalone type rings (without bars) and screws. The non-return valve is integrated into the air inlet elbow. Breastplate loops and communications are optional. Helmet is available in Tin plated or polished finish. Shipping weight approximately 39 lbs.

Threading Specifications;

Air Inlet Elbow threading is 1 1/16" - 17 (Submarine Thread).

Front faceplate threading is 5 13/16" - 20

Window Guard Screws are #8 - 32 NC.

Neck Ring Threads (interrupted) is 8 15/16" - 6

Head opening in Neck Ring is 8 3/8"

Breastplate stud & wing nut threading is 7/16" - 14

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Browne Commercial Diving Helmet

The Browne Commercial Diving Helmet is similar in design to the Japanese and Bob Kirby helmets favored by many commercial divers. Its standard features include oversized screw in windows sealed with O-rings, an integrated air control valve, a large air diffuser/muffler, a low profile air/communications block, and a double exhaust valve. The air inlet can be adapted to a variety of hose fittings including 1 1/16"-17, 9/16"-18 Oxygen, and JIC. The helmet is fitted with a four wire Marsh Marine type plug set up for two wire operation, but can be adapted in the field for four wire operation with the addition of significantly reduces the chance of water leaking back through the exhaust valve. The breastplate is a standard lightweight type used on the Sponge, Abalone, and Agar Helmets. The bolt pattern and shape is similar to the Japanese, Chinese, and the fiberglass breastplates in use today. A pair of combination lashing post/eyelets are standard, but Mark V loops or no fittings are an option. Helmet comes standard in heavy tin plating. Shipping weight approximately 45 lbs.

Optional for Browne Commercial Helmet:

Breastplate loops P/N 21149 (can be substituted for pad eye and post)

Threading Specifications;

Air inlet port in block (for Non-return valve) 1/2" NPT

Communications cable port in block (for bulkhead fitting) 9/16" - 20

Front window threading is 5 13/16" - 14

Side and top window threading is 5 1/8" - 14

Neck Ring Threads (interrupted) is 8 15/16" - 6

Head opening in Neck Ring is 8 3/8"

Breastplate stud & wing nut threading is 7/16" - 14

Composite Beat Engel

DeepSea DSL B-2 Helmet Wiring Diagram

When DESCO receives a B-2 Helmet from CBE it is wired according to common usage in Europe. DESCO rewires the helmet to suit our customer base. Below is a diagram of the wiring configuration of DSL B-2 helmets delivered by DESCO to customers in the Americas since March 2007. If your umbilical does not match this configuration simply move the helmet pigtail connections (Red, White, Green, Black) to the correct terminals on the block. The binding posts should always have a direct route to the earphones. The microphone should be routed to two of the pigtail wires by themselves.

A printable copy of this diagram is available on our Downloads Page .

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