E as sealing

No diving possible without a good seal!

Definition

A fundamental concept that makes the difference between a successful dive (with our precious audiovisual equipment and our dry testicles) and the banal messed up, shivering and on the verge of drowning dive ...

Synonymes

Dry | Waterproof | 

Starter

By definition, diving is practiced underwater so that as a land biped you are at least wet and in any case not waterproof. This is not necessarily serious for a naked human body, unlike the equipment necessary to penetrate and evolve underwater… All the skill of the first divers consisted precisely in having waterproof equipment manufactured. These include diving bells and other barrels of Leathbridge, the first heavy-footed spacesuits and their successors, other more or less rigid envelopes. 

Because, in diving, everything must be waterproof or almost: watches and their digital successors, lamps, batteries, cameras and cameras, gas cylinders (in both directions), underwater thrusters and up to to (dry) clothes

Nothing is more difficult than to make a closed enclosure watertight and over time, the most diverse and even eccentric solutions have been used: oiled leather sleeves, various greased yarns and fibers, tow (hence the “stuffing box”), felt, bitumen, flat gaskets tight to death, more or less elaborate then natural rubber turned synthetic, synthetic polymers and elastomers, silicones… And the worst thing is that it worked! Yves omer of which we recounted some of the adventures here would have a lot to say about the tricks used to seal the bubble of life Precontinent 3 back in the days when O-rings did not exist ...

The fight against water ingress in diving equipment is a real saga. The first cameras for example (built by Dimitri Rebikoff to name but one), once loaded and closed, were inflated with a bicycle pump which maintained a positive pressure in the sealed chamber. Thus, in the event of a leak, it was the air which came out in bubbles before the water entered, thus warning the diver and allowing him to ascend before the disaster ...

Main course

Friend Heuzey who filmed the first episodes of the show with me Dive logs used a massive cylindrical box containing the first Betacam's, professional digital cameras which were a major advance over old “film” technologies but remained heavy, bulky, not to mention the price (we were still very far from “GoPro”). This is how, in the hope of protecting his investment, I often surprised him, stuffing his box with dish sponges!

It would take a book to tell the most beautiful adventures of water withdrawal by a material in principle intended for the opposite. All divers had to suffer. But if I had to remember just one, it would probably be this dive to Turks & Caicos or Virgin Islands unless it is at four days in Antigua, in any case in one of these islands with coconut palms, dream beaches and easy girls ...

My box!

I have already touched on the subject briefly in the article C as box but after all, when you love you don't count. We were coming out of a recreational and boring dive, too short, too hot, too blue, full of those disgusting sponges and corals of the Caribbean and those stupid pairs of angel fish. There was in the group a saddle with white teeth, equipped like an airplane carrier: it did not lack a trinket and at first glance it looked like a Christmas tree. A photographer ! In other words, the wound ...

It was equipped with a precious metal housing, with a latest generation Reflex, motorization, optical return, ultra-wide angle lens without distortion, compensated dome, pilot lights, huge flashes at the end of articulated arms, in the shape of a giant crustacean. The set must have cost an eye and probably both arms (underwater, the guy was a broken arm…) and if it wasn't gold plated, it was the spirit. We were all back up waiting for the photographer who had this detestable habit of attaching the box to a hanger to then reassemble “the precious” in complete safety…

- Everybody aboard ?

The skipper, wanting to impress his people, suddenly pushed the throttle down for a dazzling start worthy of the “rear wheel” exhibitions of the unbridled motorcycles of our suburbs. Alas, the boat fell in a spray of foam and a large “tacatac” of crumpled sheet metal.

- My box!

The still ballasted end had described an arc of a circle and the famous forgotten box had gone up in the propeller ... The guy turned all green was twisting his arms like a madman on the end to finally hoist his dripping crab with golden claws onto the deck. . He was also slowly resuming colors having noticed and happily announcing to the crowd that there was only a drop of water in the porthole! I would be remiss all my life to have undeceived the unfortunate by explaining to him that obviously it was not a drop of water but a bubble of air ...

Dessert

It is thomas edison the first to use a flat round rubber gasket to seal his “filament light bulb” between the metal base and the glass bulb of the bulb. The inventor thus preserved the vacuum inside the bulb. It should be noted that this innovation rich in developments, considered as a simple accessory part, will not even be filed by this brilliant industrialist with a thousand patents for inventions ...  

Thus, for the practice of diving, it was necessary using a bronze hexagonal wrench to tighten as a deaf these flat gaskets, small black rubber washers, between the valve and the regulator to hope to dive without leaking. air. Although the divers of the time were often spotted thanks to the column of bubbles that escaped from their bottles ...

It remained to invent the O-ring, as its name suggests in the shape of a torus where the pressure was distributed evenly over the entire surface and even reinforced the seal. An idea that seems obvious today, it still had to be invented. What was done in 1937 by an industrial designer named Nils Anton Christensen.

In 1933, it was in the basement of his house that he tested the prototypes of these gaskets which deformed under pressure to conform to the shapes of the gasket surfaces. 4 years of trials - errors while cutting the joints himself by hand, in the midst of the dry clicks of the joints which burst, sometimes being slapped on the fingers until they bleed… October 2, 1937, aged 72 , he finally files the patent application which will be granted to him on November 21, 1939! Waterproof.

The Second World War ensued where these new kinds of seals were widely used for armaments and aeronautics, without even asking the authorization of the inventor, moreover. I have these maniacal details from the psychopath collector and nevertheless friend Philippe Rousseau which we will consult with profit this excellent article.

But it wasn't just the regulators to seal. The valves on the bottles were then with conical thread, which implied that “the relative metal-to-metal tightness (chrome-plated brass on steel or on aluminum) could only be achieved over 1 or 2 turns only”. We obtained the seal with cable wound between the male and female threads, before tightening again beyond reason… It was time to switch to cylindrical threads made watertight with… An O-ring! We know of all sizes, all profiles (some in four leaf clover or daisy to increase the contact tangents) and all materials (rubber, Teflon ...) to adapt to all conditions of use, the temperature, in particular. 

Because these filthy O-rings are not just for diving waterproofing. the January 28, 1986, during the STS-51-l mission, one of the large O-rings of the right booster booster of the space shuttle Challenger did not inflate fast enough because of the ambient cold that day, causing a leak of ignited fuel which reached the support of the booster until it broke, within a few seconds. The nose of the booster hit the center tank and detonated it. The shuttle disintegrated in flight 73 seconds after launch. No member of the crew survived ...

See you soon for a new definition of Scuba Bécédaire. The irreverent lexicon of diving, but not only. Because sometimes ...

Francis Le Guen

 

 

Café

And for collectors and other psychopaths of diving watches, these few jovial considerations on the waterproofness of your wrist jewelry ...