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Luis H

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Thank you. For a non US denizen, would you care to explain D.O.T ? I've never came across it before.

Unless I'm very much mistaken, those tanks were also in use in the French Navy during Cousteau's time. According to Frédéric Dumas (can't remember in which book though) they were the best tanks ever. More stable than the later iron twin sets and easier to adjust on the back as they were shorter. No idea if it's just an opinion or a fact.

The UDS system was something US Divers (now Aqua Lung) sold in the 70's to loosely imitate the "Hydro-Dynamic" dive kit that the Calypso divers used in the 60's and early 70's. The only real similarity is that they both have an outer yellow shell. That is the only thing they have in common.

Cousteau or the Calypso divers never used the UDS system. If you notice the UDS system can only be used with the built in single hose regulator. The regulator first stage was built into the valve manifold and it could not be replace or use a different regulator.

Cousteau always preferred the use the use of double hose regulator even after the single hose regulator was becoming popular. A lot of it had to do with appearance that was associated with his original equipment.


Cousteau did use a variety of triple cylinders (and some sets of 4 cylinders). His preference was multiple cylinders with a custom manifold that allowed keeping one cylinder shutoff as a reserve cylinder. They used the reserved cylinder approach instead of using a pressure gauge. Cousteau considered a pressure gauge to be unsightly on his films, and distracting.

The early multi-cylinder kits used in "Silent World" (Mondo Silente) did not use any type covering shell. They only started using the yellow shell with the "Hydro-Dynamic" suit that was used in the "Undersea World of Jacques Cousteau" series. The kit was specifically designed for this series to have a futuristic look. The double hose regulator was chest mounted and it included a helmet with a built in light. Underwater communications was also part of the design, but that didn't work so well.
 

justadyver

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DOT (Department of Transportation) cylinders are relatively light weight cylinders designed to be portable or at least intended to be transportable across state lines. And that is why they are regulated by the DOT.

The DOT agency was previously know as the ICC or Interstate Commerce Commission. Many older cylinders are stamped ICC instead of DOT. I own several ICC cylinders.

Because the cylinders are intended to be lighter (for transportation purpose) the fabrication method requires for them to be formed from uniform material and heat treated without the use of welding material.

Because these cylinders are designed and built with very minimal safety factor and basically zero corrosion allowance, they require periodic retesting and re-qualification. The typical 5 year hydro test (and VIP) for all 3AA or 3AL pressure vessels,


ASME cylinders or pressure vessels on the other hand are designed and normally intended for stationary installations. They are much heavier and they are designed with a larger safety factor in addition to the extra material consideration for corrosion allowance.

Because of the extra safety factors, ASME cylinders do not require periodic hydro testing.

I have designed and certified (with my engineering license) several ASME pressure vessels, but that was over 20 years ago. So, I really don't remember very much about the ASME codes. And no one ever tries to remember them, they are just too many details and they are relatively involved.

The codes have extensive details on welding procedures and fabrication detail. There is also testing and in process inspection procedures.

ASME cylinders are heavy and normally not intended to be moved once they are installed.
are 150 psi portable air compressors with 5 to 10 gal tanks dot or asme or no certs at all??
 

Luis H

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are 150 psi portable air compressors with 5 to 10 gal tanks dot or asme or no certs at all??

That is a good question. They are low pressure vessels and they are not covered under high pressure cylinder codes.

I am fairly certain that they are regulated by DOT under a different set of codes, but I have never dealt with them. They are similar to the propane cylinder and those are DOT.

That is about the extent of my knowledge about the.

I actually own a couple of those low pressure portable cylinder for filling tires and I read that they are supposed to be replaced after certain number of years (due to potential corrosion). I can't remember how long. I was wondering how many people ever do that.
 

Rol diy

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I can't remember how long. I was wondering how many people ever do that.
Until a pin hole rots though and leaks :wink:

Usually there is a plate that has all the specs on it, but never seen any stamping like propane tanks..
 

Rol diy

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I actually picked up a used UDS system ,
it was a bit butchered up, there was a silly checkball system to fill the tank, if I remember correctly , that was buggered up, and leaked,
But what a pain it was to assemble tanks, bands,
plumbing, nothing would line up, and had to be assembled all at once, I am a mechanic and I don't know how any dive store would work on it, I wasted so much time on it,

I finally sold it.
it seemed like a good idea, and i wanted it to work, but all that plastic is dumb,
 

JMBL

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CT-Rich

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JYC was a cinematographer, not an engineer. Most of the dive gear was probably created conceptually first. How would this look on film? How can we get this shot?
The practicality of the device came in second. The shells and helmets with antenna looked really cool. That neither the lights or the radios worked particularly well is beside the point. JYC probably had strict rules about gear configurations for every diver appearing on camera.

Their mini subs were cool AF, but mostly designed as camera platforms to film each other. I am not really knocking them, the end result was the birth of the environmental movement and the beginning of our understanding of the ocean as an ecosystem and a finite resource and the rise of sport diving.
 

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