Does a regulator deliver gas below its IP?

[Scubaroo]

If you have a regulator with an intermediate pressure set to 140psi, will it continue to deliver gas if the contents of the tank it is attached to falls to 140psi?

Assuming the intermediate pressure is still above ambient pressure, eg at the surface.

 

[Rick Murchison]

It will continue to deliver, at an ever increasing effort, until the tank pressure reaches ambient. If you'd like to see how hard your regulator breathes at ambient, just take off the dust cap and breathe through the reg without it being attached to a tank.
Rick

 

[padiscubapro]

Scubaroo once bubbled...
If you have a regulator with an intermediate pressure set to 140psi, will it continue to deliver gas if the contents of the tank it is attached to falls to 140psi?

Assuming the intermediate pressure is still above ambient pressure, eg at the surface.

I'll add a caveat to the previous response, for piston assisted upstream designs, a specific IP is required to shut the valve.. so in this case you hit the limit and the reg free flows til the tank is empty.

 

[-BlueHole-]

padiscubapro once bubbled...


I'll add a caveat to the previous response, for piston assisted upstream designs, a specific IP is required to shut the valve.. so in this case you hit the limit and the reg free flows til the tank is empty.

Is this also true for a Jetstrem/Odin ?
If yes what's the limit ?

 

[scubafanatic]

.......I own 3 Poseidon Odins, and my understanding is that once the pressure drops to a certain level (can't remember offhand at exactly what psi), the reg will freeflow.

Question to anyone 'in-the-know' about the Odin:

What is this pressure? Can any adjustment be done to the regulator to prevent this free-flow.......or at least get the psi where this happens as low as possible?

It has crossed my mind that in an emergency, I'd rather not free-flow this last bit of gas, but would rather be able to breathe it down to ambient pressure before it simply stops giving gas.

Karl

 

[scubatech]

scubafanatic once bubbled...
.......I own 3 Poseidon Odins, and my understanding is that once the pressure drops to a certain level (can't remember offhand at exactly what psi), the reg will freeflow.

Question to anyone 'in-the-know' about the Odin:

What is this pressure? Can any adjustment be done to the regulator to prevent this free-flow.......or at least get the psi where this happens as low as possible?

It has crossed my mind that in an emergency, I'd rather not free-flow this last bit of gas, but would rather be able to breathe it down to ambient pressure before it simply stops giving gas.

Karl

When the IP raises ie... tank turned on the air inflates the balloon (the blue thing inside the barrel) When it fills with air it stops the flow of air around it(the breathing flow) when you take a drag off the reg the diaphram presses aganist the servo valve on the end of the shaft wich allows the air to escape from the ballon, allowing air to flow around it. out the mouthpeice.
The hiss you hear when you first turn on the reg is the air bypassing the ballon untill it inflates and fills up, thus stoping the flow of air.
Thats why with an odin (or jetstream) as the IP goes up the reg gets harder to breath from. Just the oposite of almost every other reg made.
Oh ya your suposed to have an IP of 145 psi, when attached to a 300 psi source. The IP will be less when hooked up to a full tank.
:doctor:

 

[neil]

padiscubapro once bubbled...


I'll add a caveat to the previous response, for piston assisted upstream designs, a specific IP is required to shut the valve.. so in this case you hit the limit and the reg free flows til the tank is empty.

For diaphragm regs also, IP is the ONLY closing force.

 

[scubafanatic]

....thanks for the Odin 'insight'......I appreciate your details on the Odin's operation......wondered how that little 'condom' thing worked!

That's interesting about how, if the IP is increased, it becomes harder to breathe, and that being the opposite of other regs on the market.

I understand the IP on the Odin is a bit higher than average for regulators on the market today.

I have a question about getting the Odin to breathe the way I want. I like a fairly low cracking effort, but it seems when it's set that way it's prone to a little free flow on the inhale. At the end of an inhalation, but before the exhalation, the 2nd stage wants to 'burp' a bit (it vents a little air during the pause between inhale and exhale).....which is annoying. I've noticed when I put the 2nd stage switch into the " - " position it stops doing this.....but of course increases the breathing effort.

What would happen if the IP were increased? Could the Odin be set up so that, if one increased the IP, it would be less likely to vent that 'extra' air? Also, would increasing the IP lower the PSI at which the Odin will ultimately free flow, allowing one to get to use that last bit of air in a tank instead of it free flowing and going to waste.....in an emergency I'd rather get to use that last bit of air, and have it last as long as possible.

Also, if the IP were increased, the 'ballon' would fill up faster, shutting off the air , which would seem to be a good way to prevent any free flow, which I'd appreciate, as my 2nd stage, even out of the water, is prone to leak air ever so slightly (slight hiss)...which is annoying.

I assume adjusting the cracking effort is independent of the IP too? I'd like the cracking effort low, but the IP set 'high' , so that the air turns on and shuts off completely and as quickly as possible. Is this a set-up you'd recommend, or am I missing something? How high can the IP be set without damaging something in the Odin?

Karl

 

[tinman]

Rick Murchison once bubbled...
It will continue to deliver, at an ever increasing effort, until the tank pressure reaches ambient. If you'd like to see how hard your regulator breathes at ambient, just take off the dust cap and breathe through the reg without it being attached to a tank.
Rick

Ok, my dumb question of the week. Does this mean then that actual tank pressure on an "empty" tank would be:

14.7 PSI @ surface
29.4 PSI @ 33 fsw/34ffw
58.8 PSI @ 66 fsw/68ffw
107.6 PSI @ 99 fsw/102 ffw


So tell me if I understand this correctly: downstream regs don't add any additional resistance to the process which would provide in the ideal CF world an additional 92.9 PSI for an OOA diver to get to the surface (107.6 - 14.7 = 92.9 PSI) from a typical wreck dive to 99 fsw/112 ffw. This presumes temperature stays constant (no thermocline) and that there is a determined sucker at the business end of a second stage....

P.S. I'm not anxious to test the validity of this and noone should construe from the above that this an endorsement of such a practice - your results may vary as may your life expectancy!

 

[Big-t-2538]

tinman once bubbled...


Ok, my dumb question of the week. Does this mean then that actual tank pressure on an "empty" tank would be:

14.7 PSI @ surface
29.4 PSI @ 33 fsw/34ffw
58.8 PSI @ 66 fsw/68ffw
107.6 PSI @ 99 fsw/102 ffw

yes, those would be absolute pressures....not gauge pressures which would be -0- in all cases.