High pressure hose blowing, can it happen UW?

[Diver0001]

I saw an article somewhere on how long it takes to drain a tank with a high or low pressure hose failure at various depths. The low pressure hose was much quicker at all depths. The high pressure hose took a very long time to drain the tank. I will try and remember where I saw that info and post it.

Joe

I saw a post on the deco stop like that. I think Curt Bowen wrote it.

R..

 

[Groundhog246]

He should have said 30# of "force" not pressure. Using hydraulic principals, 3000PSI applied to a .01 square inch piston will only lift 30#. 30PSI applied to a 100 square inch piston will lift 3000# (that's how they lift your car in a garage). Doesn't quite apply to an HP hose, there's still 3000PSI at the end and if you tried to plug with your finger or other body part, it would be very bad. If you applied a 3000PSI jet of water to a .01 sq in area of wood, it'd punch a hole through it very quickly.

 

[Spectre]

I saw an article somewhere on how long it takes to drain a tank with a high or low pressure hose failure at various depths.

I know it was discussed a while on TDS and Curt Bowen did a bunch of tests. He wrote it up in the last issue of Advanced Diver mag.

 

[Walter]

I've seen one HP hose, actually the gauge blew, go on a dive in the Bahamas once. I believe we were at about 60 ft. It was loud, very loud, and bubbles were everywhere. The guy made a normal ascent. The LP hose will absolutely drain a tank much faster than the HP hose.

May 23, 1990. Fifth dive of the day, it was a night dive on Fishtail Reef. I believe you were diving with Donna, Bob, Peggy & Jim, but it's been a long time, so I could be mistaken. I can check my log when I get home. I was solo taking photos with John's Nikonos III, none of which came out. Max depth was 40 feet, seas were flat calm. Bob made a normal ascent.

 

[Charlie99]

Now, if your hp hose was to unscrew from your first stage, it would be very cool. And empty your tank in short order.

You should unscrew your hp hose from your 1st stage and look inside. Most modern regulators have a very tiny pinhole orifice --- unless you look very closely, it looks like the hp port is blanked off. This is why an hp hose rupture will drain the tank more slowly than an lp hose rupture.

 

[Keysdrifter454]

Maybe I'm just slow but if it only transfers 30# of pressure, why does the pressure guage read 3000#. ?

Maybe it's slow, too...

Pressure isn't necessarily volume.

The numbers aren't right, but the practical example is.

Think 100psi coming out of a garden hoes,

And 100psi coming out of a firehose.

 

[novadiver]

Maybe it's slow, too...

Pressure isn't necessarily volume.

The numbers aren't right, but the practical example is.

Think 100psi coming out of a garden hoes,

And 100psi coming out of a firehose.

I'm not so slow that I don't know the differance between pressure and volume. Thanks anyway

 

[android]

Not to go into a lot of math, but there is flow and pressure involved. If you have a single lane of traffic going 100mph, it can move as many cars as 4 lanes of traffic going 25mph. The flow of both is the same. It's the same with gases and fluids moving through pipes. 3000psi (HP) through a tiny pinhole can only pass a certain amout of air while 140psi (LP) through a much bigger orifice will move a lot more air. To be specific the LP orifice would have to be 21x the HP orifice to move the same amout of air.

I don't know the exact measurements, but this is probably close:

The HP orifice is tiny, let's say the size of a #80 drill bit which is .013" in diameter. This means the hole is about 0.00013 sq in. Let's say an LP orifice is .25" across which gives an area of .049 sq in. The LP port at 140psi would move about 17 times the air as the HP port at 3000psi.

 

[novadiver]

Not to go into a lot of math, but there is flow and pressure involved. If you have a single lane of traffic going 100mph, it can move as many cars as 4 lanes of traffic going 25mph. The flow of both is the same. It's the same with gases and fluids moving through pipes. 3000psi (HP) through a tiny pinhole can only pass a certain amout of air while 140psi (LP) through a much bigger orifice will move a lot more air. To be specific the LP orifice would have to be 21x the HP orifice to move the same amout of air.

I don't know the exact measurements, but this is probably close:

The HP orifice is tiny, let's say the size of a #80 drill bit which is .013" in diameter. This means the hole is about 0.00013 sq in. Let's say an LP orifice is .25" across which gives an area of .049 sq in. The LP port at 140psi would move about 17 times the air as the HP port at 3000psi.

Lets try it this way. a skwert gun has a large piston that causes water to go through a small hole.Now that large piston causes pressure that causes the water to shoot from the gun at an increased valocity.

IN short, if you put your hand on a punctured high pressure hose, you will lose fingers.If you think that there is only 30# of presure than have at it. It's not the volume that will cut your fingers off, it is the pressure

 

[keyshunter]

Last fall, at Cayman Brac, my wife had a high pressure hose let go near the beginning of a dive at 90 feet. We made a normal ascent--which for me is about 30 feet per minute--to the boat. I checked her gauge before we began her ascent and again when we reached the boat. She had used about 500 psi including the gas she breathed. She is a light breather and probably didn't breath more than 200 psi, so that translates to a leak of approximately 100 psi per minute.

That was my first personal experience with an underwater high pressure leak (although I have had freeflows, and low pressure leaks empty a tank in a hurry) and I was surprised at the relatively small air loss.