200 vs. 300 bar DINs

[Josh Levinson]

Hey guys,

I'm wondering what the practical differences are between 200 and 300 bar DIN connectors (both on regs and on tanks, but especially on regs). Are 200 bar DIN valves considered acceptable for technical diving, and in particular for overhead diving? I'd appreciate any info. Thanks.


Josh

 

[roakey]

A 300 BAR DIN valve has a deeper recess than a 200 BAR DIN valve. A 300 BAR DIN regulator has a longer connector than a 200 BAR regulator. So a 200 BAR regulator will only fit a 200 BAR valve, but a 300 BAR regulator will fit either a 200 or 300 BAR valve.

In addition, all 200 BAR valves that I know of come with a “doughnut” that screws into the DIN recess and changes the valve to a standard yoke valve. 300 BAR DIN valves are too deep for this to work, and some do not have the “dimple” on the reverse side that the yoke valve screw is supposed to sit in.

Personally I like having more threads in the valve (300 BAR), but I’ve used both 200 and 300 BAR DIN valves with my 300 BAR regulators without any problem. So though a 200 BAR valve with doughnuts is not optimal, it is a popular compromise since ANY regulator will be able to be mounted on it.

I do strongly recommend you stick with the 300 BAR regulator conection, since that can be used on either 200 or 300 BAR DIN valves.

Roak

 

[Josh Levinson]

Thanks for the info Roak. I have a set of OMS valves that I was told are 300 bar, but that have the "doughnut" to convert to yoke... so I don't know anymore if they are in fact 300 bar. I'll have to give the guy I got it from some !@#$ if they turn out to be 200 bar.

So are you saying that compatibility aspects aside, and just taking into account safety aspects, 300 bar valves and connectors are preferable, but 200 bar valves and connectors are acceptable? Does that apply to overhead diving as well?

Thanks again.


Josh

 

[Uncle Pug]

Originally posted by Josh Levinson
Does that apply to overhead diving as well?

Nope.... not acceptable.

And the valves you have are most likely 200 bar... sorry.

 

[Iguana Don]

A 300 bar valve has 7 threads and a 200 bar valve has 5 threads.

This should make identification easy for you.

ID

 

[The Chairman]

It is commonly accepted rule of thumb that if designed properly, MOST bolts only need three full threads to acheive full strength. However, a DIN does not have the proper thread pitch and subsequent thread depth to qualify as "properly designed" The finer the pitch, the shallower the thread, and there is a trade off here.

That being said, the only tightening done on most DINs is by the flange that is part of the threaded plug. We are not torquing these puppies down to what the threads would actually hold. Also when pressure is applied it creates a WHOLE LOT more friction on the threads, rendering removal of either the 5 or 7 threaded DIN impossible. The number of threads are not the limiting factor for the pressure either. The threads of a "sport DIN" will indeed hole 300 bar with ease... however, the valves were designed to limit the use of some regulators to tanks that do not exceed 200 bar.

The use of the different number of threads on the regular DIN and the "sport" DIN is merely to keep people from putting a reg that is only rated for 200 bar on a 300 bar valve. In spite of what some agencies may teach, it is my humble opinion, that they are making mountains out of molehills. A tank that is rated for less than 200 bar will be best served by a valve that is 200 bar. The increased versatility that is given the tank is another plus. This is yet another way to remind the tank fillers that this is NOT a high pressure tank. Unfortunately, overfilling steel tanks is "OK" with some agencies. I do not understand why they take the chance on the one and not the other!

As with any sport, there are a lot of opinions about what is best and what is "garbage". All of these opinions can be supported with varying amounts of success. However, just as I would not choose to dive beyond my limits, I also do not want to dive my gear beyond it's limits. The limits have been set by the DOT and the manufacturers, and we exceed them at our own risk. 200 bar valves are just as safe when operated within their limits (and the limits of the tank they are affixed to) as a 300 bar valve is when operated within it's limits. One should never dive beyond their training, their limits, nor their equipment's limits.

 

[Josh Levinson]

Holy crap NetDoc! I've never gotten such a comprehensive answer to a question I've asked in my entire life! I don't know if what said is true or not, but it certainly is logical. Opinions are fun, ain't they.

Thanks for the feedback guys.


Josh

 

[The Chairman]

When I attended the Universtiy of Florida, I had the chance to work as a lab assistant for about 18 months. Since the lab I worked in was a cryogenic/spectroscopy lab I got to make good friends with the Chemistry machine shop. Consequently, my last 18 months (full time during the two summers) at the U of F, actually found me as a student apprentice in the Chemistry Machine shop. I learned more about the various metals and their limits than I could ever have hoped to learn elsewhere. After that I managed a student machine, welding, and structural sciences lab for the College of Architecture. I was rated as a basic welder during this time, and I kept at learning the machinist's trade. I was also introduced to the science of statics and how things actually stood up. Although, I went back to work as an automotive mechanic (the University did not pay very well) I have always cherished the REAL education that I received at the hands of Art and Chester, who ran the Chemistry machine shop. I really have not used my major (Russian) at all, but I keep going back to the basics that I was taught as a student assistant/apprentice.

Having said all of that, although I can operate a lathe, milling machine and various other metal working machines, I do NOT consider myself a machinist. AND while I passed my first set of tests and am rated a basic welder, I did not keep up with that at all, and do not consider myself as a welder either. I do consider myself a life-long learner, and enjoy piecing together the intricacies of the puzzle of the world we live in.

 

[Uncle Pug]

Pete I know you don't do overheads....
But since the question was asked....
Which would you prefer in an overhead situation....
5 threads or 7 threads?


btw... it personally think that the DIN fitting would break at the interface with the regulator body rather than at the tank valve but I'm not going to take a hammer to mine to find out....

Anyone know?

 

[Josh Levinson]

Unlce Pug... if you're saying you think the DIN fitting would likely break at the DIN-reg interface rather than the DIN-tank interface, wouldn't that suggest that, with respect to stability, it doesn't matter whether you have a 200 or 300 bar fitting or valve (which, as I understand, only affects the DIN-tank interface)?

And who's Pete?


Josh