Regulator pressure rating.

[OldNSalty]

Quick question, according to the stampings on the yolk of one of my regs it is rated to just 3000 PSI. Am I doing significant harm to it by using a tank filled to 3300-3500PSI?

 

[redacted]

That might depend on who did the stamping and when. I'm familiar with Scubapro regs. Modern yokes, some which say 3000 psi and others which say nothing but "S", have a 9/16th inch yoke screw and I don't give a 2nd though to using them with 3500 psi. I also have similar yokes from other manufacturers that are marked "3500 psi". But I do have an older Mk5 with a yoke that is obviously lighter but stamped "3000" and has a 7/16th inch yoke screw. Scubapro technical information says it is only good for 2475 psi. I'm still using it on 3000 psi tanks but would not go over that.

 

[OldNSalty]

The part is original and its on an AL SE3

 

[captain]

Keep in mind the force per unit area. The area that is subject to tank pressure on the regulator to tank connection is about .26 square inches, multiply that by 3000 psi and the force is 780 psi of force exerted on the yoke. At 3500 psi it is 910 psi exerted on the yoke, 130 pounds more. The issue is not so much the breaking or the screw stripping as it is stretching and deforming which could let the O ring extrude.
That said, I don't feel a 3000 psi rated yoke is a big issue at 3500 psi. I wouldn't do it with a older 2450 psi yoke. Any regulator made after the 3000 psi AL 80 came on the market should have a 3000 psi rated yoke. I have used 2450 rated yokes at 3000 without problems but you can definitely see them stretch when the pressure is applied.

 

[OldNSalty]

OK-so it is the yolk and not the reg that is the issue? That is interesting. Thanks for the info

 

[SDAnderson]

OK-so it is the yolk and not the reg that is the issue?

Not eggsactly.

 

[cerich]

you guys are forgetting the design pressure on the HP seat as well. Some are only made to handle 3000psi and can have stress problems when exposed to higher.

 

[captain]

you guys are forgetting the design pressure on the HP seat as well. Some are only made to handle 3000psi and can have stress problems when exposed to higher.

As in the yoke situation the force per unit area on the seat is much less because of the far smaller area of the seat, basically the area of the orifice the seat rests against. Assuming an orifice of .100" the force on the seat at 3000 psi is 23,5 psi, at 3500 psi it is 28 psi, 4.5 psi more. Hardly enough difference to matter .

 

[redacted]

you guys are forgetting the design pressure on the HP seat as well. Some are only made to handle 3000psi and can have stress problems when exposed to higher.

What reasonably modern regs are not available with a 300 bar DIN connection? Those should be the only ones that may have HP limitations beyond the yoke connection. I can't think of any Scubapro 1sts where the HP seat might be a limitation.

 

[Luis H]

I don't think it would be much of a problem to the seat, especially in a balanced piston it would not mater. The closing force is always basically the same.

But, the high pressure O-ring in an old Mk-5 can have a tendency of getting extruded with higher pressures. That should not be the case with newer first stages.

The old Conshelf (or RAM) should not have a problem either with the -ring back up ring.