200 BAR DIN vs 300 BAR DIN

[rx7diver]

I've got a silly question. If regulator has 300 bar DIN fitting does it means that it can handle true 300 bar working pressure?

No. When I purchased my first PST 3,500 psig HP 80's ca. 1988, I purchased Scubapro 300 Br DIN connectors to replace the yokes on my Scubapro Mk 10 1st stages. (The HP 80 shipped with a 300 Br DIN valve.) The reality is, Scubapro's claims to the contrary, my Mk 10's were only marginally happy with the 3,500 psig service pressure of the HP 80. And they weren't happy whatsoever with the 4,000 psig cave fills my HP 80's received at some dive shops near the Great Lakes. (4,000 psig < 300 Br.)

Safe Diving,

rx7diver

 

[redacted]

No. When I purchased my first PST 3,500 psig HP 80's ca. 1988, I purchased Scubapro 300 Br DIN connectors to replace the yokes on my Scubapro Mk 10 1st stages. (The HP 80 shipped with a 300 Br DIN valve.) The reality is, Scubapro's claims to the contrary, my Mk 10's were only marginally happy with the 3,500 psig service pressure of the HP 80. And they weren't happy whatsoever with the 4,000 psig cave fills my HP 80's received at some dive shops near the Great Lakes. (4,000 psig < 300 Br.)

Safe Diving,

rx7diver

But was that because of the din fitting limitations of because of other Mk10 design limitations. I suspect that 300 bar din fitting is good for 4500 psi. I would not be surprised if the 200 bar din fitting also handled that pressure with no problem. Any limitations are probably elsewhere in the 1st stage design.

I suspect the Mk10 HP piston o-ring was the source of your problems.

If you put 160 MPH speed rated tires on a VW bug do you think it will then do more than 90 MPH?

 

[rx7diver]

I've got a silly question. If regulator has 300 bar DIN fitting does it means that it can handle true 300 bar working pressure?

But was that because of the din fitting limitations of because of other Mk10 design limitations. I suspect that 300 bar din fitting is good for 4500 psi. I would not be surprised if the 200 bar din fitting also handled that pressure with no problem. Any limitations are probably elsewhere in the 1st stage design.

I suspect the Mk10 HP piston o-ring was the source of your problems.

If you put 160 MPH speed rated tires on a VW bug do you think it will then do more than 90 MPH?

awap,

I answered bogdan.zivano's question by supplying him one real example of a regulator, though fitted with a manufacturer-supplied 300 Br DIN connector, was almost certainly not able to handle 300 Br tank service pressure (since it couldn't handle 4,000 psig, and only marginally handled 3,500 psig).

As to your question, I suspect the problem was due to the regulator's design. Not too much later, Scubapro began offering the "Mk 10 Plus" as a replacement to the "Mk 10." The Plus has a different piston and seat and spring and has other design differences, as well. Scubapro offered a kit to upgrade a "Mk 10" to a "[psuedo] Mk 10 Plus." I upgraded two of my three 10's to pseudo Plus's, to use, briefly, with my HP cylinders, and subsequently have experienced no more problems&#8212;at 3,500 psig. (I actually purchased Poseidon's to use with cave-filled HP cylinders shortly after I upgraded my 10's to Plus's. I use/used the Plus's for rec diving, and the Poseidon's for tech diving in cold Great Lakes water.)

I am not a certified Scubapro tech, though I service and rebuild most of my Scubapro regulators. I was told by a certified tech that the problem with the 10 is it doesn't control its intermediate pressure well at high tank service pressures. It is unstable at high tank service pressures. This tech told me that the Plus was a quick fix for this before the Mk 20 [sic] began being offered. (And then the 20 had its own issues, as you're probably aware, which is why the 25 was introduced very shortly after that!)

Safe Diving,

rx7diver

 

[redacted]

awap,

I answered bogdan.zivano's question by supplying him one real example of a regulator, though fitted with a manufacturer-supplied 300 Br DIN connector, was almost certainly not able to handle 300 Br tank service pressure (since it couldn't handle 4,000 psig, and only marginally handled 3,500 psig).

As to your question, I suspect the problem was due to the regulator's design. Not too much later, Scubapro began offering the "Mk 10 Plus" as a replacement to the "Mk 10." The Plus has a different piston and seat and spring and has other design differences, as well. Scubapro offered a kit to upgrade a "Mk 10" to a "[psuedo] Mk 10 Plus." I upgraded two of my three 10's to pseudo Plus's, to use, briefly, with my HP cylinders, and subsequently have experienced no more problems&#8212;at 3,500 psig. (I actually purchased Poseidon's to use with cave-filled HP cylinders shortly after I upgraded my 10's to Plus's. I use/used the Plus's for rec diving, and the Poseidon's for tech diving in cold Great Lakes water.)

I am not a certified Scubapro tech, though I service and rebuild most of my Scubapro regulators. I was told by a certified tech that the problem with the 10 is it doesn't control its intermediate pressure well at high tank service pressures. It is unstable at high tank service pressures. This tech told me that the Plus was a quick fix for this before the Mk 20 [sic] began being offered. (And then the 20 had its own issues, as you're probably aware, which is why the 25 was introduced very shortly after that!)

Safe Diving,

rx7diver

I take it from your response that the problem was the HP seat performance. That seat design was used in the Mk5 and its variants as well as the Mk10. I have run into some early versions of those seat where the seat itself (different material than currently used) seemed to break up resulting in uncontrolled flow exceeding designed intermediate pressure. Once that seat starts to fail, losing control of IP, the rising IP can drive the piston knife edge well into the seat as it just breaks apart. With earlier Mk5 pistons, there was little to no shoulder restricting the travel of the piston and it would just drive itself through the seat until the slightly thicker shaft near the piston head lodges in the body. Mk10 pistons and newer Mk5 pistons have a fairly large shoulder that limit the travel of the piston should such a failure occur. I guess that is the failure mode you are talking about. The current seat design (cave cone seat) seems to do OK with pressures in the 3500 psi range. I have used my Mk5s (most with the earlier design piston) with HP100 with no problems. Although, 300 bar or 4500 psi might be a whole new ballgame.

I believe newer designs (MK10+, MK15/20/25) did away with the sharp "knife edge" piston in favor of a somewhat duller, or downright rounded edge that would not cut into the seat as much should an IP problem develop. But I suspect the biggest contributor to the fix was in the seat materials which they still seem to play with from time to time. With the balanced piston design, theoretically, the effect of changing high pressures should be tertiary - until it is not.

 

[kensuf]

Holy zombie threads.

quick answer - 200 bar has a shorter thread depth. A 300 bar first stage can fit into a 200 bar valve, but the converse is not true.

have a nice day.