Al Krasberg

For diving deeper then 60 meters the breathing gas for the diver must be blended because oxygen and nitrogen which are part of ‘normal’ air become toxic when respired under a certain pressure. Pure oxygen can be respired at a very limited depth only, respiring oxygen in a blended gas under pressure becomes toxic too depending on the level of oxygen in the mixture and the pressure ( depth ) The lower the oxygen level, the deeper you can go with it.

So to be able to dive deep the oxygen level must be decreased to a level where it is not toxic and that is done by blending it with Helium which is a neutral gas which can be aspired at any depth.

After the first world war there was a large stock of ‘surplus’ helium available for tests, but after this gas was used up it turned out to be very expensive to have gas manufactured for deep diving. In order to ‘save on the gas’ helmets were equipped with ‘recirculating systems’. The recirculating system lets the diver respire the same gas over and over but the oxygen level is controlled and the carbon dioxide is filtered out. This way the volume of helium needed for deep diving was decreased to less then a third compared to a ‘free flow’ diving system.

Alan Krasberg designed a ‘Return line Diving System’ which was a rebreather system, divided between the diver under water and the ship where he dived from: the main rebreather was at the surface on board of the ship. His assistant in the project Jim Bathgate Sr. initially rebuilt an Aquadine DMC7, later a Kirby Morgan 17 diving helmet for use with his system, and several versions followed. The helmet is known as the ‘Krasberg’ helmet. It can be identified by the large regulators which are built to the sides of the helmet.

Jim Bathgate

On september 6 2012 this website received an interesting email:


I've been looking at your website it's very informative, thank you.

I used to work with my father , building Krasberg Reclaim systems, (my father was working for Al Krasberg in 70s and 80's)

I have some helmets, but I had to promise not to part with them before my dad gave them to me (in bits).

I've attached a photograph of one I have almost finished re-assembling. The original was based on a DSI 17a, with a remoulded shell to incorporate the exhaust regulators.

Best Regards

Jim Bathgate

September 9 2012:

Scan 1.jpeg

Yesterday I went to my father's house and looked out this black and white photograph, taken by Aberdeen Journals. We are looking for the newspaper in my father's house, hopefully, soon I will find it and get copies for you. The photograph is my father, working for KD Marine in the 1970s, (you can see the badge on his coveralls!) This was his very first working prototype based on a DSI 17a (Kirby Morgan)  but the original is long gone, along with the previous one which was simply valves bolted to a General Aquadyne helmet. I think it was called a DM7 or DMC7 ? I will have to look it up.I recall him taking a 17a to bits on the kitchen table, took a hack-saw and kept the neck ring and front section, then totally remoulded the shape for a new shell.

The building where the photograph was taken is still there, oddly enough, I was inside it a few weeks ago, a different company is there now, they powder coat equipment, and I got them to shot blast the Tin from  my Chinese TF12 helmet and corselette

Three helmets:-  black one is 17a style,this photo shows a Desco "pot" open circuit valve on chin,like early ones.

white one is a complete hat, "as used". It has a spring load pin on face port, (supposed to be an inward relief valve in case of blowback when oxy-arc broco cutting, but more often used by a diver to let a small amount of water into hat to demist)

Blue one has no exhaust valves, no more parts in my box, a guy in a car repair garage painted it metallic for me. It will look almost complete after I fit a dummy exhaust elbow on outside. I also need to solder a piece of 10mm copper to the end fittings to make a proper size hard pipe assay, which connects the 2nd stage to the supply block, as they are longer than a normal 17b. Internal exhaust regulators far too complicated to copy.

This photograph shows a prototype helmet my Dad was building just before Al Krasberg sold out GDS to Divex/pressure products. The canister on the right side is full of soda-sorb, a bailout system, but it never progressed past prototype.

September 10 2012:

Hi David,


It's Ok to use these pictures. The MD of pressure products/divex called my Dad and said he was calling all ex-employees of GDS, because people had stolen things and one guy tried to sell jewel regulator valves to Stena Offshore. He said he did not mind my dad having any helmets etc, that was not a problem, but not to sell them to diving companies. Actually, my Dad was polite but replied that anything he had,he owned and mostly because he made them himself, at home.

I don't know how big an article you would write, but out of my respect for my Dad, it would be very nice to see something like that,a little bit of recognition so to speak. This isn't relevant to reclaim helmets, but somewhere in my parent's house there is a black and white photograph of my Dad in Benghazi harbour, and another taken off the

coast of Libya in 1950's, he is wearing twin hose scuba. The British army was mapping a sunken city. I have no details,but will ask my Dad if he remembers more.I will also look for those pictures. He learned to dive with the REME (royal electrical and mechanical engineers) where he did 2 years "national service".

Last thing to say, the guy who is selling the Krasberg helmet on ebay should not sell it too cheap, they will be scarce already,no-one would really make a copy. Nice to see it though.



September 10 2012:

Good morning Jim,

Thanks for your long emails, much appreciated.

Would you be OK with it when I use your comments and photographs for my website? I have near to nothing right now so it will make a good base for a complete story on the 'Krasberg' helmet. Is Krasberg still alive? 

Please let me know if you are OK with me showing your photographs and the story about the reclaim helmets on my website, thanks.

Best regards,


September 10 2012:


Forgot to attach these pictures of a prototype helmet my Dad was working on before GDS closed. scrubber canister for soda sorb visible on right side. Never really completed.pity!

I can take better pictures later for you.




 Jim Bathgate

September 11 2012:


I just went to Aberdeen, picked up the sheet from the Newspaper, 14 Feb 1978. My Dad had an Aquadyne helmet with hand made exhaust regulators in 1977, tested in the simulator (basically a chamber plumbed like a bell, with a flood able lower portion, so the diver actually entered the water to simulate being "locked out". The idea was Al Krasberg's one, he handed my dad A BELLOWS FOOT PUMP FOR AN INFLATABLE BOAT and said "this could work on a helmet for an exhaust valve that closes when the diver has breathed out". I have tried to scan the paper, but it is dull, I will get a copy if possible, from the newspaper HQ.




 Jim Bathgate

Evening Express, February 14 1978, by Alan Krasberg.

In the constant quest to improve safety and comfort for divers in North Sea operations - plus financial savings - diving firms are pressing ahead with developments and innovations as fat as they can.

One such development of a helium recycling system designed to save on operational costs, reduce the amount of shipboard area devoted to gas bottle storage, and contribute to the divers’ operational comfort.

Helium is used in large quantities for divers at great depths.

Instead of gas being used and allowed to bubble to the surface afterwards the exhaled gases are returned to the surface reprocessing unit via the diver’s umbilical cord, where they are scrubbed, re-pressurized and returned to him.

The resultant is considerable, as the only gas loss is by equipment leakage.

Present-day helium prices are around 20 cents per cubic foot so it costs in the region of 60 american dollars to keep a diver supplied while working at 300 feet for 20 minutes or 600 feet for 10 minutes.

Using the new development, this cost - the cost of one bottle plus topping-up quantities - would be the total amount required for an on-going dive.

At the moment there is a world shortage of helium, which makes this development even more important.

The differences in equipment between the normal system and the new one are basically the helmet and umbilical cord.

With the conventional helmet the exhaled gas bubbles out of the outlet valve and neck dam (seal) which crates noise above the divers head and can interfere interfere with communications and reduce vision.

The new helmet has five valves through which the exhaled gasses pass back into the lower pressure of the umbilical cord on their way to the surface.

These independent valves ensure safety for the diver, as all five must fail before he is in trouble. Failure of any one will generate a warning signal for the diver.

On developing the new system I found that the almost constant through passage of gasses makes the interior of the helmet almost as comfortable as the old-fashioned ‘heavy dress’ helmet.

I and another man originally pioneered the idea in 1973, when such a system was used on the United Stated Underwater Habitat, Sealab 1.

Used sporadically since then, the development was seriously looked at again in 1975, when commercial saturation diving requirements on the North European Continental Shelf took a dramatic upturn.

Production of the units is expected to begin shortly, with some parts being made in Britain.

. Mr Krasberg is research and development manager with international diving company K.D. Marine, who have a base in Aberdeen, at Dyce.


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