Low Pressure vs High Pressure Air Loss Test
After receiving an email from one of our subscribers, telling us of an incident that occurred to him while diving at one of our local quarries, we invited him to join us at the pool to simulate his catastrophic failure. We then compared our results to his incident and looked at the equipment itself to determined why a diver loses so much air at depth during a catastrophic failure. We want to give a big shout out to Steve Nash, for sharing his story with us, and for coming out to help us do this experiment.
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Rating: 4.86
another excellent video, keep 'em coming. also it pays to consider the failure may come 1/2 way or greater thru the dive giving you seconds of usable air.
Brilliant exercise and demonstration. Glad im setting up a pony bottle . Dont care if others laugh at me.
The valve leak time seems misleading. As far as breathability from your lines. If you are having that much volume loss at the source of intake to your first stage. How much is actually making it to your second stage would be my question. Furthermore would it be sufficient enough to actually get a breath off it. Granted some is better than none but depending on the answer buddy breathing seems to be the safer option. Love your videos man! very educational and presented in an approachable supportive manner
Great video thanks for this info.
I have always wondered why manufacturers don't put a smaller orifice on the low pressure ports. Large enough to supply the heaviest breathing at depth, and good bcd inflation rate, but smaller to limit extreme free flow like that.
Tx for this demonstration!
This guy's an expert. Thanks for sharing your knowledge. You guys will save lives.
LP results will be much worse at depth, the first stage is letting more air through, so at depth LP failures could be instantly catastrophic, should do this LP test at 100 ft, the HP test will not be much different
Should repeat the HP test using DIN, then you might think differently about your yoke preference (PADI DM for 15 years 🙂 ) Been there done that
I think there is an error to your calculations.
Namely – airtime.
Shouldn't you take into account divers air consumption?
I believe that would cut the hp hose failure air time by half
And this is why I don't dive in pools anymore! Hoses be gett'en cuts all the time……
I'm surprised the valve leaked slower than the LP hose. I would think gas could escape faster out of the valve (from 200 bar down to 1.3 bar) than out of the LP hose (from ~10 bar down to 1.3 bar). But it looks like you had the first stage attached with all the ports open, so maybe it's the same intermediate pressure? I'm still missing something here…
Why everyone is obese? Fat absorbs lot of nitrogen….
I had a diver jump in right on top of me from the dive boat in Bonaire in 2014. The bottom of his/her tank just missed my head and smacked the top of my regulator (Scubapro Mk 5). The high pressure hose snapped off flush with the first stage reg body (the threaded part of the fitting was retained). Once I gathered my senses, it took me a minute or so to realize I had a big freeflow coming from the first stage. The second stage never freeflowed. I never got deeper than 15-20 feet. I made a slow ascent back to the boat, never had a breathing restriction. As I was climbing up the ladder, the last of my gas was hissing out. Looking on my computer, the entire episode took about 3 minutes from getting hit to climbing up the ladder. The reg has a small HP orifice, and the HP hose fitting has a small orifice as well (and it remained in the reg). It should have taken a longer time to lose that gas. The best I can figure is that the blow broke the o-ring seal between the reg and the tank, so I sort of had two high pressure failures at once. My wife actually got a couple of pictures of the freeflow. Its pretty impressive. The reg was never the same–wouldn't hold stable IP even once everything was replaced and overhauled. I figured the body of the reg was damaged, so I retired it. It's now a paperweight with a good story attached to it. I never got a visual ID on the diver who smacked me (more concerned with the state of my head). Whoever it was swam away, never fessed up and never even mentioned it.
Very informative
I'm rewatching this video, and noticed something I missed the first time around: the SPG is leaking before the HP line is cut. Is that why you sacrificed this one?
Thanks for posting, surprised at the results in this experiment….. good job done….
Loving your content. Going to learn scuba. Love it.
thanks
I don't understand the final line of your calculations, surely a leaking hose will take the same time to empty (or less, because of slightly lower pressure differential) at depth as it does near the surface?
And do the calculations take into account the air used by the diver as he ascends? Or just the air lost by the leak?
He mentioned he went to his "bailout"… can you tell me what he had? And do you recommend any backup air supplies? (Spare Air"?)
Thanks for including the data also in Metric
If you get a free flow , would it be good to try to turn off and on valve as you need to breathe? Or maybe get your buddy to?