Strange IP behavior on a freshly serviced regulator - what's going on?

[rhwestfall]

and then there is Poseidon....

 

[Kharon]

Limits. Everything has it's limit. I bet if you put an IP gauge on that, you'll see a higher IP when you first pressurize it.

I check my IP pressure everytime I service any of my regs. It always pops right to 135 or 140 (depending on where I set the 1st stage) My Cressi 2nd stage likes 135, the Hollis 140.

 

[The Chairman]

I check my IP pressure everytime I service any of my regs. It always pops right to 135 or 140 (depending on where I set the 1st stage) My Cressi 2nd stage likes 135, the Hollis 140.

Then you have the cracking pressure set just right. Without the thhhhhhpt, I bet the IP would be higher.

 

[Kharon]

Then you have the cracking pressure set just right. Without the thhhhhhpt, I bet the IP would be higher.

Yeah. That's what I wonderd. If maybe Hollis designed that little purge on pressurization to go easy on the gear.

 

[The Chairman]

If maybe Hollis designed that little purge on pressurization to go easy on the gear.

Probably not, but who knows? More likely a happy little accident. I'm still going to hold down that purge until I hear a hiss and then I'll gently let go.

 

[Rusty Shackleford]

It could be internal sticking or the HP seat not being broken in.

However, if you're not holding in your purge as you pressurize your tank, you're doing it poorly. No, not wrong, but you're slamming that knife edge into the seal at 3,000 psi. Holding the purge softens this initial blow considerably. Try that and tell us what the initial IP sits at when you do. I bet it will be normal.

^Exactly right. Always hold the purge or the inflator button if you need to add a bit of air to the BC before you put it on. I am convinced a hard pressurization does more damage to the seat than many hours of normal use. I learned to purge while pressurizing two decades ago.


Therefore, my initial IP is always where it wants to be.

 

[Rusty Shackleford]

What happens if you slowly crack open the tank?

No reason not to do both.

 

[halocline]

It could be internal sticking or the HP seat not being broken in.

However, if you're not holding in your purge as you pressurize your tank, you're doing it poorly. No, not wrong, but you're slamming that knife edge into the seal at 3,000 psi.

No you are not; IP closes the 1st stage valve, not supply pressure. You're only applying 150 PSI times the area of the piston head (or diaphragm) force on the knife edge. As an example, if the piston head is 1 sq" in area, and the IP is 150 PSI, you're exerting 150 lbs of pressure on the knife edge.

 

[The Chairman]

No you are not;

Sure you are. Don't forget the initial momentum of the first closure. There is 3,500 on one side and 145 on the other.

But hey. You don't have to lessen the impact by holding down the purge valve. I'm still gonna!

 

[MichaelMc]

and then there is Poseidon....

Off topic, from a series I enjoy:

"There are precisely fifty High Houses. And then there is Korval."

(There are at least two opposite types of interpretations of such a statement.)