Old Us Divers Snorkel With Continuous Drainage

An insatiable man

Emile Gagnan was not only a genius inventor he was also an insatiable man always seeking perfection. French engineer at l'Air Liquide, born in 1900, he is the inventor who found the solution for J.Y. Cousteau and transformed the "Gazogène"  into a scuba diving regulator in 1943.

When the first "Scaphandre Autonome" hit the market in 1946, it was a huge step ahead allowing the scuba pioneers to discover the underwater world, though it was far from being the last one.

Even though CG45 was providing enough quantity of air to support life at very decent depth, thanks to the two stages and a respectable air orifice diametre's section, the regulator was nevertheless hard to breathe, complex to manufacture, maintain and adjust.

Emile Gagnan was already looking for a way to ease up inhale effort, simplify maintenance and reduce costs, all at once with a whole new concept.

A tricky problem to solve

Very soon after CG45 hit the market, Emile Gagnan was already looking to invent a new regulator to quench his appetite to simplify the mechanism, lower the manufacturing costs and obtain a much easier to breathe scuba regulator.

The problem was not simple to solve.

On a two-stage regulator, (like the CG45) the force the diver has to produce to lift the seat and open the valve is only struggling against the intermediate pressure of the regulator. This is around 8 bars,  the surrounding pressure is present on both sides of the seat and does not affect.

This means the regulator combines the two following features:

• Large enough air orifice to let flow a considerable amount of air to supply the diver
• Small enough force to lift the second stage valve within a "human breathing" range.

On a simple stage regulator, things are a bit different. The air pressure is brought directly from the High Pressure in the tanks (let's say 150-200 bars) to the surrounding pressure (one bar at the surface) in only one step (so-called single-stage).

That means if the HP orifice is too big, being an upstream design valve, the force to lift the valve will be way beyond what human lungs' force can produce, even helped with a simple mechanism to amplify it.

Doing the maths, if the HP orifice is 1 square cm, the force to lift the valve would be 200Kg (…), but if it is only 1square mm, the force to lift the valve decreases to 2Kg…

The right balance between being breathable (force to lift the valve) and quantity of air provided (diametre of the orifice) would then be the crucial sweet-spot to seek.

Another invention came to Emile Gagnan's help. A two levers mechanism was the solution to amplify the force generated by the diaphragm to press on the pin and lift the HP valve in a simple and cheap way. Gagnan could now have a section large enough to support life at any depth on a breathable single-stage regulator.

The last challenge: CG45 required a constant inhaling effort from the diver to maintain the diaphragm in a lower position keeping the MP valve open to deliver air supply. In other words, you have to suck the air out of the regulator during all inhaling phase to stay alive. Emile Gagnan was looking for a mechanism that could ease up this effort.

To achieve that, he understood he needed to do two things:

• Balance the air pressure contained in the regulator's can with the one close to the diver's mouth.
• Create a depression in the can's chamber to maintain the diaphragm in a lower position during the inhalation phase of the divers.

Doing so, the effort to "take-off" the HP valve would be minimum and the air would be delivered to the diver with no additional effort.

This is how many different solutions will be tested, some of them even hit the market before the final result was reached. Let's see that

First single-stage ever: DX Over Pressure

DX OVERPRESSURE (1954 – 1956) is the very first intent from Emile Gagnan to invent a single-stage regulator. DX, produced in Broxton Ave facility, hit the US market in 1954. He will never be commercialised in Europe.

The mechanism is quite extraordinary, it separates the air pressure contained in the regulator's can (which is only used to open the HP's valve) from the one supplying air to the diver.

When inhaling, the diver creates a depression in the 1-inch admission hose that moves the diaphragm in its low position, pressing on the pin and opening the valve against the tank high pressure. The air rushes through a secondary small hose inside the 1-inch hose, directly from the body single-stage to the diver's mouthpiece at a higher pressure than into the diver's mouth.

The "Overpressure"  name comes from that.

While the diver keeps inhaling, the depression in the regulator's can persists and the regulator keeps delivering air with no additional effort. When the diver stops in-breathing, the diaphragm goes back into its initial position – thanks to two small holes in the main body underneath the levers – and closes the HP valve.

DX OVERPRESSURE mitigates the small HP orifice with a superior air pressure delivery to allow enough air quantity to support life at sport-dive depth.

What a brilliant idea! Well done M. Gagnan!

US Divers was so excited by this new regulator and its performance they didn't even wait for the patent to be registered (the patent will be registered the following year, Feb. 07th, 1955) and commercialized the regulator in 1954 based on the CG45's one!

DX was cheaper than Aqua Lung Trademark, its 1955's catalogue price was $60 vs. $80 for the two-stage regulator. Nevertheless, DX surprisingly didn't receive the warm welcome he deserved.

Thing is, instead of providing a "strong wind" of air, it was supplying an unpleasant laminar jet air through the secondary smaller green hose directly into the diver's mouth. Some shop repairmen were even saying that DX stood for "Damn Xuberent!"

Heavy metal mouthpiece, limited head movement (due to the small inside hose)  and laminar jet air were strong drawbacks. DX was quickly disregarded by divers and later on turned into a DW Mistral by replacing the nozzle and getting rid of the smaller hose.

The concept is outstanding and with a bit more engineering around the manufacturing to overcome the deficiencies (longer hose, lighter mouthpiece and better mouthpiece injector…)  this regulator would probably be an absolute scuba champion.

Read the full story here

1955 US DIVERS' Catalogue  extract

DW Stream Air: we 're almost there!

Emile Gagnan understood very quickly the limitations presented by DX OVERPRESSURE. The solution was looking good on the paper of the patent registered in Feb. 07th, 1955 but, as usual, the devil lies in the details, and the side effects were not encouraging to keep this course of action.

On the same patent, Emile Gagnan registered another invention to solve his problem in a very different way. This time the idea was to equip the regulator's body with a nozzle to reduce the quantity of air coming from the tank and pointing it toward the edge of the intake horn to divide the air into two streams.

• One part of the air stream would become turbulent inside the regulator's can. This would help to replace the diaphragm back in its original position when the diver stops inhaling.
• Meanwhile, the rest of the laminar stream would rush into the intake horn, creating suction inside the regulator's can and generating a Venturi assistance effect.

Now Emile Gagnan had 2 parameters to play with (diameter of the nozzle orifice and its orientation regarding the intake horn) in order to obtain the best compromise between air quantity and easiness to breathe.

This is actually how DW STREAM AIR hit the market in 1956, it will be manufactured until 1957. It was sold for $65, still cheaper than his double hose cousin "DA NAVY APPROVED" though presenting better performance and a light Venturi assistance effect.

Another step forward, DW STREAM AIR is equipped with a brand-new mouthpiece "Kleer E-Z" introduced this very year. Kleer E-Z presents two non-return valves on each side to clear the mouthpiece much easier.

1956 US DIVERS' Catalogue  extract

The first low-cost regulator: DY Jet Air

Even if DW STREAM AIR was cheaper than DA NAVY APPROVED, there was still some room on the manufacturing side to reduce costs in order to market a cheaper regulator and seduce Diving Schools, Store Rentals, and limited budget divers: This time the regulator's name is DY JET AIR

Based on the good performance of Stream Air mechanism, US Divers decided to market in 1956 the revolutionary DY JET AIR at a price of… 45 US Dollars! Almost half of the price of DA.

DW JET AIR is equally fitted with a small air injector that aims at the border of the intake horn to create and control the Venturi assistance. It is a cheap regulator made with Phenolic, a remarkable synthetic thermosetting resin that doesn't need any chrome treatment nor labels to attach or welded horn, this regulator is now moulded. It comes black or brown in colour and is equipped with the Kleer E-Z mouthpiece.

This low-cost regulator will be produced for 2 years only, in 1956 and 1957. It will though revive in 1961 with the 1020 JET AIR.

It is amazing to see how US Divers was advanced on their time, it is clear today that manufacturing a "plastic" regulator was the way to go, even if 1956 was probably a bit too soon for divers' mentalities.

Mistral... at last!

The issue with Stream Air is that one of the parameters to find the right mix was the angle of the nozzle regarding the edge of the intake horn, which is somehow not giving much room to tune the regulator precisely.

This time, the regulator is equipped with a specific geometry injector aiming directly into the intake horn. This nozzle is capable of generating a secondary stream perpendicular to the main flow in order to balance the suction effect. This is the third option from the Emile Gagnan's 1955 patent: the famous Mistral Nozzle.

Mistral Nozzle will be mounted in an uncountable number of regulators from US Divers and other manufacturers and will culminate the seek of Emile Gagnan.

His name "Mistral" makes reference to the strong Mediterranean wind which blows on Bandol where the very first sea dive with CG45 were performed by J.Y.Cousteau, P.Tallez and F.Dumas back in 1943.

This time, the two parameters to find the best compromise are way easier to control. It is the diameter of the holes of the main and secondary air stream which will pilot the performance of the regulator and the quantity of air supplied to the diver. This is it!

The first models manufactured probably late 1957 at W. Pico Boulevard facility came without any serial number for a short lapse of time. They already present far better performance than any of their single-stage predecessor and deliver plenty of air at any depth with minimum breathing effort thanks to the Venturi's assistance created by its nozzle. They are equipped with black hoses and a straight Kleer E-Z mouthpiece.

In 1958, Mitral is marketed with a yellow pair of hoses and a straight mouthpiece at a price of $65. The same year, DA Aquamaster catalogue's price is $90.

Amazing to notice the draw in the 1958's US Divers' catalogue represents a DX Overpressure with a "Mistral" Sticker… really!!

1958 US DIVERS' Catalogue  extract

Alongside with DA Aquamaster introduced the same year, DW MISTRAL is a major breakthrough in US Divers regulator's line. (see the full story about 1958… and then came Venturi). It will be manufactured through a great bunch of many manufacturers and names across the globe and represents one of the greater, if not the greatest, commercial success in the scuba history.

The Blue Mistral case

The story behind this Mistral regulator is truly amazing. In 1956, after dropping the commercialization of DX, US Divers signed a contract with the SEARS Company in order to allow the company from Chicago to sell DX OVERPRESSURE under their brand of sporting goods named  "J.C. HIGGINS"

This time the DX OVERPRESSURE regulator was renamedAQUA AIR LUNG, it was painted in blue and a sticker was replacing the riveted yellow label.

J.C.HIGGINS had the blue AQUA AIR LUNG during two years on its catalogue and stopped advertising it in 1958. Surprisingly at the very same time appeared on the market a BLUE MISTRAL branded by US DIVERS that was actually a DX OverPressure painted in blue with a sticker instead of a label.

This DX was updated with a Mistral nozzle and a straight mouthpiece… Even on some of them, you could see underneath the Mistral sticker, the J.C.HIGGINS AQUA AIR LUNG light green original sticker…

How come US DIVERS launched again the manufacturing of DX Overpressure when Mistral, a far better regulator, was already on the market and upgraded it with a Mistral Nozzle to eventually paint it in blue and sell it as Mistral…

In 1958, US Divers had manufactured a large stock of J.C.HIGGINS AQUA AIR LUNG to supply SEARS Company with. When the later eventually stopped ordering them, instead of throwing away these perfectly good regulators, US Divers decided to put them back on the market.

Of course, they couldn't sell them as-is, let say in their DX OverPressure condition, so US Divers upgraded the AQUA AIR LUNG with a Mistral Nozzle, equipped it with a straight mouthpiece and sold it as Mistral of course !!!

It is hard to say today how many were manufactured and sold as Mistral, though this regulator is extremely rare and for this reason is very collectable.

The revival of Overpressure and Stream Air

With the arrival of the new "Mistral" in 1958, a far more performant than all its predecessors, lots of divers decided to upgrade their "Damn Xuberent Overpressure" to seize the advantage and comfort of the Venturi assistance. They turned their DX into DX Overpressure Mistral, this was done by replacing the nozzle, getting rid of the green hose and mounting a straight Kleer-EZ mouthpiece. A "Mistral" sticker was then placed on the front of the can to identify this particular regulator was upgraded

This upgrade was performed and recommended by the shop's repairmen using a transformation kit manufactured by US Divers. Lots of DX Overpressure were transformed, their green hoses changed for a Mistral Nozzle and replaced the metal mouthpiece for a Kleer E-Z (which meant you also had to change the two 1-inch hoses)

Of course, a complete transformation would have implied replacing the body of the regulator – as DX and DW's bodies are slightly different – but even like this, the performance was very close to the original DW Mistral.

As a result, it is hard to find today an unmolested DX Overpressure in its original configuration because a great number of them were updated by their owners.

Pretty much the same happened to Stream Air Mistral, truth is it was much less needed than with DX but nevertheless, many of them were equipped with the Mistral nozzle and upgraded. They also were granted with the "Mistral" sticker.

Mistral "early Warner"

In 1960, US Divers moved in their new facility in West Delhi Ave (Santa Ana – California). At that time US divers had some labour troubles and event sent part of the DAAM's production to be manufactured overseas, this is the so-called "made in France".

The 1960 and 1961 US Divers' Catalogues show Mistral model though I have never seen any DW Mistral with West Delhi address label. What happened during those two years is a mystery,  if someone knows the story I would love to hear it.

In 1962 the street was renamed to West Warner Ave and this is the address US Divers' regulators will have until the end of the double hose regulators production in 1973.

Very little improvement about early Warner model vs. W. Pico's one. The only appreciable difference with the 58′ model is the curved mouthpiece introduced in 1961. The rest is identical.

Make new with old and call it Jet Air

In 1961, US Divers re-took the manufacturing of the 1956 DY JET AIR, called it this time 1020 JET AIR, to again supply rental shops and diving school with a cheap and robust regulator. 1020 JET AIR is this time made of Cycolac (ABS) instead of Phenolic like its predecessor and comes with a black and white label sticker.

We could think that being produced in 1961, the new 1020 Jet Air this time would have grasped the improvements of DW MISTRAL, (from 1958), and be equipped with the famous Mistral nozzle and its incredible Venturi assistance effect. Well, that would be too much thinking… Actually, except the label which is now a sticker pasted on the front can, and small variance on the diametre of the exhaust, the rest of the regulator is absolutely identical to its predecessor the DY Jet Air. The mechanism is still based on DW STREAM AIR , not produced since 1957!

1962 US DIVERS' Catalogue  extract

Looking at the inside of the regulator, you can still see the small air injector aiming at the border of the exhaust horn, exactly like its predecessors DW STREAM AIR and DY JET AIR.

Again, it is amazing to notice 1020 JET AIR is equipped with the straight mouthpiece (when the far more comfortable curved one was introduced this very year of 1961) and this until its last year of production in 1963…

All in all, it really looked like this 1020 JET AIR was produced with a unique purpose of making a low-cost regulator that even if without embracing the latest development of DW MISTRAL would be good-enough for teaching and renting.

THE ROYAL MISTRAL

The background

In 1965, after 7 years lifespan, DW MISTRAL had suffered no major improvement and few evolutions were brought to its original design. DW MISTRAL was somehow technically falling a bit behind its competitors. The previous year (1964) US Divers decided to go one step further and commercialised ROYAL MASTER. Based on DA AQUAMASTER but this time featuring a balanced first stage.

It was time to upgrade DW MISTRAL, this development would bring an innovative upgrade based on a real technical difference. It would place this new regulator on a matchless level and maintain US Divers at the edge of innovation.

The technical solution

It is remarkable to see how much of a Frankenstein ROYAL MISTRAL  is. Made with parts of Royal Master/RAM and DW Mistral, Royal Mistral has few parts of its own. It really seems to be an in-between regulator. All in all, the technical innovation has been limited to very few numbers of components.

Marketing placement is not clear

US Divers ROYAL MISTRAL has only been commercialised for a couple of years between 1965 and 1968. Based on the serial numbers,  it seems US Divers may have manufactured a figure in the neighbourhood of a thousand of RM.

The catalogue price in 1965 is $64,95 a bit higher than DW MISTRAL ($47,50) and a bit lower than DAAM ($71,50). This was probably a marketing misstep that confused many potential buyers. Either your budget was limited and you would go for DW MISTRAL or in case of mandatory need for an intermediate pressure, a DA AQUAMASTER; or, you had a higher budget, and for $90 you would definitively go for a ROYAL MASTER and get " the regulator for those who want the best "

So ROYAL MISTRAL's market positioning in US Divers' catalogue, was unclear and that probably made it difficult to sell. I guess this is another major reason divers didn't line up to order it and as a result, the regulator didn't have the commercial success it was intended to have.

Read the full story here

Mistral "late Warner"

DW MISTRAL will be produced at West Warner Ave, Santa Ana (CAL) from 1967 until 1970. US Divers will drop its production the same year and we will have to wait 35 years to see another Mistral.

DW MISTRAL hasn't changed much since its introduction on the US Market back in 1958 (see the very first model) and had a lifespan of a dozen years. Only appreciable changes compared to the first models are the curved Keer E-Z mouthpiece, the long yoke to accommodate the banjo fit and the Serial number on the label. The rest remained practically unchanged.

After trying with DX OVERPRESSURE and DW STREAM AIR,  DW MISTRAL was finally the answer from US Divers to produce a single-stage easy to manufacture and maintain to cover the low-end market of scuba regulators. Thanks to its Venturi assistance nozzle introduced by E. Gagnan (see my post "1958… and then came Venturi"), DW MISTRAL was providing a great deal of air at any depth and with a very low breathing effort compared to its competitors.

Produced in a number of tens, if not hundreds, of thousand by US Divers, and by other companies, this regulator represents one of the greatest commercial achievement.

The last of the tribe: Aqua-Lung Mistral

Aqua-Lung Mistral is the last double hose built by the scuba diving equipment. This come-back to the origins of scuba equipment has been hugely motivated by the commemoration of the 50 years of the model in 2005, being 1955 the year Spirotechnique Mistral hit the market and replaced CG45 in France. In the US, DW MISTRAL will be marketed as of 1958.

This time, the new Mistral is not a single-stage regulator anymore. The idea of Don Rockwell (president of Aqua Lung America at that time) is to combine the best features of the old double hose regulator – including having the bubbles come out from behind the diver's head and not obstructing the field of vision – and updated it with new modern regulator technology. As a result, Mistral is now a balanced two-stage unit based on the Aqua-Lung Titan for the first stage (we don't present this extremely reliable regulator) and the Calypso mechanism for the second making the spare parts extremely easy to source.

Mistral is completely sealed from the external environment and particularly reliable on cold water diving, the DIN and high/medium pressure plugs make it versatile and easy to set with modern equipment. It will be manufactured in DIN or International variant and will also have a "limited collector" version with its wood box, carbon look and authenticity certificate.

When the regulator hit the market in 2005, he received a mitigate (to say the least) review from the diving community, of course, used to dive with modern and far lighter-to-breath single-hose regulators.

Even if the name seems to be the sole link between new Mistral and the original model, it is nevertheless the last specimen of a long and unique family that was born more than 60 years ago in the mind of a genius engineer and insatiable man: Emile Gagnan.

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Source: https://vintagescubadiving.com/tag/us-divers/