Curt Bowen
Contributor
scubabills:
about 80-90 seconds
If you broke a low pressure hose?
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about 80-90 seconds
pete340
Contributor
TwoBitTxn:
It's about 140 psi above ambient pressure. (almost 10 atmospheres, if you don't want to do the math).
On second thought, I missed your point. Yes, there is very little difference in intermediate pressure with different regulators.
android
Contributor
Breaking at the threads could mean it was over torqued during assembly.
The hose to regulator torques are only supposed to be slightly past hand tight.
The hose to regulator torques are only supposed to be slightly past hand tight.
android:
Yup! Second most common reason for them breaking is over tightening, the most common is impact.
Tighten them by hand, then **snug** them down with a wrench. Remember, just like your first stage sealing to you tank, the O-ring does almost all of the work. You only want them snug enough so they do not loosen, thats all!
FWIW I had a low pressure hose blow twice. First time at 33m (108ft), second at 17m (56ft).
The rate of loss of air was 105 bar/minute. My 10l/72cf bottle emptied in just under two minutes.
If it happens ever again, I would be quite happy to gauge my ascent based on these figures. If I were down to reserve of 50 bar I'd have 30 secs to get to the surface.
Seadeuce
The rate of loss of air was 105 bar/minute. My 10l/72cf bottle emptied in just under two minutes.
If it happens ever again, I would be quite happy to gauge my ascent based on these figures. If I were down to reserve of 50 bar I'd have 30 secs to get to the surface.
Seadeuce
Charlie99
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Or preferably, to get to your buddySeadeuce:
.
The quickest way to lose gas is a ruptured LP hose (dpeth doesn;y play that much an issue here since there is a great pressure differance between the source (rupture) and ambient).. a Freeflow second will drain it slower depending on the regs performance.. a ruptured HP hose takes a long time..scubabills:
Curt at ADM ran some test, and his numbers showed expected results the time to drain an 80 using his zeagle regs was 82 seconds.. This isn't too far off what the manufactures says the first stage can deliever.. If you go to something like the new poseidon xtreme regs the stated max flow rate of the reg is about 2x greater than the apeks/zeagle design, so it should be considerably faster.
As indicated above, a lot depends on the flow rate the first stage is capable of maintaining.
Reg manufacturers figure max flow rate for a first stage by essentially removing one of the LP ports and letting things rip. A Scubapro balanced piston Mk 25 will produce flow rates of approx 300 SCFM while the diaphragm MK 16 will produce a flow rate of about 170 SCFM. A lower performance unbalanced piston reg like the MK2 will have a flow rate of 40-50 SCFM.
The tank valve also is a factor as some offer more restriction than others.
In any event the loss of a LP hose at the first stage is about as bad as it gets as there is much less flow restriction than with a freeflowing second stage. The only significant restriction present is the remaining threads from the fitting and the slightly smaller orifice that results.
Absolute IP will increase with depth, but the IP relevant to ambient pressure will remain the same so there no real increase in flow rate at depth with this type of failure. At extreme depths, the increased viscosity of the air under pressure should actually reduce the flow rate, but then at that extreme depth you'd be extra screwed anyway due to increased ascent time. As a practical matter, the IP the reg can effectively maintain in a high flow situation depends entirely on the flow rate of the first stage anyway.
But suffice to say that with a high performance first stage, a tank can empty much quicker than you would normally expect in that situation and far quicker than it will empty though a freeflowing second stage.
Reg manufacturers figure max flow rate for a first stage by essentially removing one of the LP ports and letting things rip. A Scubapro balanced piston Mk 25 will produce flow rates of approx 300 SCFM while the diaphragm MK 16 will produce a flow rate of about 170 SCFM. A lower performance unbalanced piston reg like the MK2 will have a flow rate of 40-50 SCFM.
The tank valve also is a factor as some offer more restriction than others.
In any event the loss of a LP hose at the first stage is about as bad as it gets as there is much less flow restriction than with a freeflowing second stage. The only significant restriction present is the remaining threads from the fitting and the slightly smaller orifice that results.
Absolute IP will increase with depth, but the IP relevant to ambient pressure will remain the same so there no real increase in flow rate at depth with this type of failure. At extreme depths, the increased viscosity of the air under pressure should actually reduce the flow rate, but then at that extreme depth you'd be extra screwed anyway due to increased ascent time. As a practical matter, the IP the reg can effectively maintain in a high flow situation depends entirely on the flow rate of the first stage anyway.
But suffice to say that with a high performance first stage, a tank can empty much quicker than you would normally expect in that situation and far quicker than it will empty though a freeflowing second stage.
NOVIZWHIZ
Contributor
I would think a blown Hp hose would be worse - guess the CFM loss would be higher on the LP? I've blown HP hoses and the gas goes quick...also the remaining hose will nearly beat you to death..
Actually no, a blown hi pressure hose will not empty faster. If you look in the reg you will see that there is a tiny orifice to restrict the flow in such an event.
If the fitting breaks you are screwed... get to your buddy and ascend normally using YOUR air until it is gone, and then finish your safety stop and such on their air.
If the hose or second stage fitting breaks, you might buy some time by folding the hose over and hold it that way. In any event, your dive is over and an ascent is in order.
If the fitting breaks you are screwed... get to your buddy and ascend normally using YOUR air until it is gone, and then finish your safety stop and such on their air.
If the hose or second stage fitting breaks, you might buy some time by folding the hose over and hold it that way. In any event, your dive is over and an ascent is in order.
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