High pressure hose blowing, can it happen UW?

[Warren_L]

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

In the old days, training manuals told you to turn the pressure guage around when turn on the tank so if the glass failed it wouldn't cause injury. I wonder why if it is only 30# of pressure ?

You're comparing two different things. One is a pressure measurement and the other is a measurement of force. The force over a specific surface area is pressure.

 

[wedivebc]

When I am teaching tech students about failure points, I will take a HP hose off the 1st stage and turn on the tank for 30 seconds. The pressure in the tank will drop about 100 psi. I then do the same thing with an LP hose and after 30 seconds there is about 1000 psi drop. I usually do this demo when someone tells me a second spg is a failure point.

 

[Charlie99]

Last fall, at Cayman Brac, my wife had a high pressure hose let go near the beginning of a dive at 90 feet.

What did the bubble cloud look like? I've noticed that HP leaks around the neck-to-valve seal on tanks puts out a fine mist of tiny bubbles. Does the HP hose bubble cloud have a distinctive look to it?

 

[dweeb]

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

30 lb. of FORCE. Pressure is force over area.

 

[novadiver]

30 lb. of FORCE. Pressure is force over area.

So a tank doesn't need a regulater , it just needs a small diamiter hose?Wow and I spent all that money on apex regs

 

[novadiver]

Just so you all know, I'm just haveing fun with this thread.

The correct answer is : 3000# psi, the psi part stands for pounds per square INCH, sense the hose is not a square inch in diamiter there will only be the force of the actual diamiter of area.

thanks for playing,

My next question will involve 1 pound of lead , Does it really equal 1 pound of feathers?

 

[android]

Well, as an example of something that can really cut your finger off, a water jet cutter spits out a tiny stream of water at around 35,000 psi. That's 10 times the pressure in a scuba tank and they use water with abrasive grit in it.

 

[keyshunter]

What did the bubble cloud look like? I've noticed that HP leaks around the neck-to-valve seal on tanks puts out a fine mist of tiny bubbles. Does the HP hose bubble cloud have a distinctive look to it?

The bubbles were numerous, but very small. Not at all like a low pressure burst where the bubbles are large and billowing.
Now this leak was in the side of the hose. They might be larger if the end was cut off cleanly.

 

[Walter]

My next question will involve 1 pound of lead , Does it really equal 1 pound of feathers?

Yes, but it doesn't equal 1 lb of gold.

 

[perpet1]

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

You are 100% correct if the hose broke at the tank fitting and you got close enough to the oriface. The force will disapate as the stream disperses. I have demonstrated this concept many times with the HP hose removed to prove the point. You would need to get very close to the oriface in order to produce the results you discribe (I have not got close enough to the oriface to demonstrate a finger being lost but you need to get pretty close with cardboard to cut it). I doubt that the hose would have sufficient pressure to cut cardboard but I will test it tonight.

I have an old reg that I use to demonstrate the difference between an HP hose failure and an LP hose failure. The only precaution is not to have your hands near the ports (I demo this by removing the ports on the reg to simulate a ruptured hose)

Just as you said with a squirtgun, the force is intense at the opening BUT disapates quickly.