200 vs 300 bar manifold

[ArmoredDiver]

I have a 200 bar OMS manifold that I would llike to use on a set of HP100s. Is this OK to do? I also have a set of LP95 that are already assembled with a 300 bar OMS manifold that I could switch so the 200 bar is on the LP tanks and the 300 bar is on the HP tanks. Thanks!

 

[ae3753]

200 BAR and 300 BAR rating is about the number of threads, there is no relationship to LP or HP.

200 BAR on your HP100s are fine. However, if the OMS manifold is the captured O-ring one, I prefer the rotating isolator.

 

[Cave Bum]

The only real issue is where you live, or more specifically where you get your fills. The 200 Bar Manifold is not (technically) supposed to see HP (3442 or 3500 psi) fills. They work just fine for HP fills, however.

The 200 Bar manifolds have less threads to screw your DIN fittings into so they are quicker to assemble your regs to. If your LDS has no problem with HP fills on a 200 Bar Manifold, you'll find it easier to use.

200 BAR and 300 BAR rating is about the number of threads, there is no relationship to LP or HP.

Sorry, but you're wrong. 200 Bar and 300 Bar are measures of pressure 200 times atmosphere (2940 psi) and 300 times atmosphere (4410 psi).

Be safe and have fun in the water! Bruce

 

[Gombessa]

Sorry, but you're wrong. 200 Bar and 300 Bar are measures of pressure 200 times atmosphere (2940 psi) and 300 times atmosphere (4410 psi).

I think the point ae3757 is making is that a 200bar manifold is not less strong, nor less-pressure-rated than a 300bar manifold; the naming convention really applies only to physical compatibility with certain types of regs (and I don't see 200bar DIN regs around), so the difference is really not an issue for most people.

This is a good article explaining the differences here (PDF)

"Is a 300 BAR SCUBA valve outlet stronger than 200 BAR?

No, they are the same. Only the first few threads in both the 200 BAR and 300 BAR outlet designs are doing the work, the remaining threads on the 300 BAR outlet are there simply to create a deliberate incompatibility with a 200 BAR connector. In fact, in practice, the 300 BAR valve outlet has proven itself to be more fragile than the 200 BAR valve outlet. The 300 BAR valve outlet is so long that the smallest 'ding' on the edge of the opening can slightly warp the cylindrical opening, causing the regulator to become difficult or impossible to completely seat. This problem does not seem nearly as pronounced with the 200 BAR valve outlets; although it remains an issue and all DIN outlets should be protected from dings."

One thing to be aware of: 200bar manifolds come with lower-pressure burst discs than do 300bar manifolds, so if you put a 200bar manifold on HP tanks (or plan on overfilling on a 200bar setup), make sure you have the high-pressure burst disks installed.

 

[Cave Bum]

I think the point ae3757 is making is that a 200bar manifold is not less strong, nor less-pressure-rated than a 300bar manifold; the naming convention really applies only to physical compatibility with certain types of regs (and I don't see 200bar DIN regs around), so the difference is really not an issue for most people.

200 Bar manifolds are most definitely 'less strong'. Strength is calculated by shear through the thickness of the thread at mid point of contact. Thickness times number of threads tells you how much material you have in shear. More threads equal more material in shear equals higher rated strength.

When engineers design items like this we add a ‘safety factor’ which is standard to the industry so it’s not designed to fail exactly at the rated pressure, hence the 200 Bar manifold will work for higher fill pressures but saying it is ‘not less strong’ or even that it was designed for ‘high pressure’ is incorrect.

 

[ae3753]

I was too quick and incomplete in my response, and additional detail is appreciated.

For scuba purposes, it is acceptable to use 200 bar for HP or LP tanks.

Industry example of this is the convertible valves that use 200 bar valves with yoke inserts for all new HP tanks.

As the result, 200 bar vs 300 bar ends up a discussion of thread length, compatibility of regulators (in the off chance that you have 200 bar DIN regulator), and how many turns you want to do before you seat the regulator in the valve.

Gombessa makes a good point about the burst disc.

However, with cave fills getting more aggressive maybe things will change in our usage of 200 bar and 300 bar valves?

 

[Cave Bum]

However, with cave fills getting more aggressive maybe things will change in our usage of 200 bar and 300 bar valves?

Don,

When I was working in a fill station just down the road from Ginnie several years ago, we were filling to the same level everyone is now. I haven't seen fills going over about 4100 psi (which usually cool to 3800 psi). The 200 Bar manifolds saw those fills day in and day out and had no problem with them. There is one brand (I forget which one) that had only one O-Ring on each side of the barrel (the center connector) and we would tend to steer folks away from using that brand but in all honesty the second O-Ring is just a safety and never sees pressure unless the first fails.

Bruce

 

[Scared Silly]

CB is correct, the extra two threads do provide more a greater shear strength but the question remains is a 200 bar manifold designed to be used at working pressures higher than 200 bar. To my knowledge yes they are. As such, as noted the extra two threads become a physical compatibility issue.

 

[WD8CDH]

Because of elasticity of materials, most of the stress is on less than 5 threads so for all practical purposes, they are both the same strength. When this DIN connection first came out, it was 5 threads and commonly used at 4500 psi. In fact, I have an old Poseidon DIN regulator, rated at 4500psi, that only has 5 threads. (I have personally used that regulator at 7,500psi on 5 thread DIN valves on titanium tanks for hundreds of dives) The 7 thread version came out for intentional incompatibility of filling.

If you look at most "200 bar" valves, you will usually see that they are stamped 232 bar or 240 bar. OMS rates both their "300 bar" and "200 bar" DIN or DIK/K valves and manifolds to 4500psi.
http://www.omsdive.com/downloads/cyl_bands_valves.pdf

From a technical standpoint, the single o-ring face seal manifold is superior as far as sealing against pressure because the o-ring is fully captured and retained by a metal to metal connection, just like the DIN regulator fitting. The double and triple o-ring barrel style manifolds are more prone to o-ring extrusion but in the real world, if the o-rings are replaced every few years, it's not a problem.

The biggest advantage of the single captured o-ring face seal manifolds is they are stronger against bending from lifting the tanks by the manifold. I have seen dozens of barrel style manifolds that have been bent but I have never seen a bent captured o-ring face seal manifold that was bent.

The biggest disadvantage of the single captured o-ring face seal manifolds is they are not adjustable for center-to-center spacing so they require better built, tighter tolerance, bands to match the fixed spacing.

I use both styles but slightly prefer the single o-ring face seal.

As far as "200 bar" vs. "300 bar" DIN, I far prefer the "200 bar" version because of adaptability to yoke regulators and still safely handling any current SCUBA pressure and beyond.

 

[alyafi]

Hello all,

I will not argue about weather 300 BAR valves are stronger than 200 BAR valves, but you should know that 300 BAR valves with the longer thread can sometimes be more sensitive to warping than the 200 BAR threads.

I have both read this online and experienced it with rental cylinders. In all fairness these were very old rental cylinders (18 years old), but the 200 BAR thread rental cylinders do not exhibit the same problem.

It only takes a small part of the valve threading to be warped to make it impossible to screw in the first stage. On the 300 BAR valves there is more thread to worry about.

As is probably common knowledge, a good visual inspection program for DIN valves will include the use of a couple of special tools for testing the threads where the valve connects with the tank and the first stage. For the first stage mating tests, the valve tools are the negative to the DIN opening as follows 1. a "pass" thread where it is able to screw all the way in and 2. a "fail" thread where the distance between the thread grooves is slightly larger than the correct distance.

A couple of different certified cylinder technicians that I had the chance to speak with pointed out this problem associated with the 300 BAR valves.

Best of luck to all with their tank purchase decisions!