Low pressure hose failure

[I Dive]

In this particular case however 20 minutes into the dive at 70 FSW, with about 800 lbs of air remaining turning my head to the right to see if my buddy was follwoing to the the ascent line, they decided to part company, something less than 10 seconds later I had NO AIR. Peter

I think you should have already been on way your up the ascent line before you reached 800 psi. To be at 70 feet and on your way to the line with 800 psi is cutting it close in my book. Glad everything ended up OK!

 

[texdiveguy]

OP.... I have never seen this occur with a lp hose as you described.....glad it all worked out ok for you on the dive.

 

[deepstops]

I think you should have already been on way your up the ascent line before you reached 800 psi. To be at 70 feet and on your way to the line with 800 psi is cutting it close in my book. Glad everything ended up OK!

A blanket statement based on what? We don't know what kind of tank the OP was using.
~700 psi in my single steel 130 is the same amount of gas as 1000 psi in a single AL 80.

 

[I Dive]

A blanket statement based on what? We don't know what kind of tank the OP was using.
~700 psi in my single steel 130 is the same amount of gas as 1000 psi in a single AL 80.

A blanket statement just based on my opinion and how I dive. You are absolutely right, I have no idea what size tank the person was using. But, no matter what size the tank is, I think 800 psi is low to be on your way to the line at 70 feet. I prefer to be on my SS at that psi. I'm well aware that many divers will consider that wasted gas or sacrificed bottom time or whatever, but I consider it peace of mind...

 

[InTheDrink]

From Deepstops...

I completed the test on the surface (0 feet) with 4 aluminum 80ÃÔ and a Zeagle D50 regulator. Here are the results

1. Failed Burst Disk = 72 seconds
2. Failed HP Hose = 22 minutes
3. Failed LP Hose = 83 seconds
4. Free Flow High Performance Regulator = 255 seconds

....

This is kind of alarming. And counter-intuitive. I would always have thought a HP failure much worse. How frequent does this happen and what are the received measures if it does happen (assuming buddy and Pony not available).
CESA?
Can you breathe off a failed HP hose?
Stick your pinky in it?

I've just never heard of this in this mode (I've only ever considered it where the HP is jammed on so you disconnect it from your BC).

Be interested to hear:
a: frequency and typical causes
b: remedial actions if it does occur

Thanks OP and DeepStops for bringing yet another potential calamity to my conciousness

John

 

[deepstops]

From Deepstops...

I completed the test on the surface (0 feet) with 4 aluminum 80ÃÔ and a Zeagle D50 regulator. Here are the results

1. Failed Burst Disk = 72 seconds
2. Failed HP Hose = 22 minutes
3. Failed LP Hose = 83 seconds
4. Free Flow High Performance Regulator = 255 seconds

....

This is kind of alarming. And counter-intuitive. I would always have thought a HP failure much worse. How frequent does this happen and what are the received measures if it does happen (assuming buddy and Pony not available).
CESA?
Can you breathe off a failed HP hose?
Stick your pinky in it?

I've just never heard of this in this mode (I've only ever considered it where the HP is jammed on so you disconnect it from your BC).

Be interested to hear:
a: frequency and typical causes
b: remedial actions if it does occur

Thanks OP and DeepStops for bringing yet another potential calamity to my conciousness

John

Your HP hose is connected to your SPG. A LP hose is what's connected to your BC inflator.

If you look at a HP hose, the inside diameter at the regulator side of the hose is a tiny pinhole and it's a same size opening on many HP ports on the first stage. That's why that failure mode takes so long to empty the tank.

In the case of a LP hose failure, there's a no replacement for a good dive buddy. If you want to try and solve yourself (or if your solo), it depends on whether or not you can reach the failure point. If you can, folding over the hose is a viable option. Otherwise, feathering the valve off/on to get gas as you need it may work as well. The caveat to that is that most recreational divers I see can't reach their valves.

 

[InTheDrink]

Your HP hose is connected to your SPG. A LP hose is what's connected to your BC inflator.

If you look at a HP hose, the inside diameter at the regulator side of the hose is a tiny pinhole and it's a same size opening on many HP ports on the first stage. That's why that failure mode takes so long to empty the tank.

In the case of a LP hose failure, there's a no replacement for a good dive buddy. If you want to try and solve yourself (or if your solo), it depends on whether or not you can reach the failure point. If you can, folding over the hose is a viable option. Otherwise, feathering the valve off/on to get gas as you need it may work as well. The caveat to that is that most recreational divers I see can't reach their valves.

Turning my valve on/off is one of my weekly drills and I don't find it arduous at all. But that was with a free flow in mind. With 83 seconds or whatever it takes for the tank to empty on an LP failure, I wasn't sure whether this kind of action would make much difference.

Any 'inconveniences' to expect with folding over the hose? Like the hose exploding etc.?

And excuse my ignorance, but on a technical level, what is the difference with a HP hose jamming on and a 'failure' of this kind that will empty a tank so quickly? Is jamming on more likely sand etc. where this kind of failure is structural. Sorry if I'm asking dumb questions, but it's the only way I learn.

J

 

[dumpsterDiver]

A blanket statement just based on my opinion and how I dive. You are absolutely right, I have no idea what size tank the person was using. But, no matter what size the tank is, I think 800 psi is low to be on your way to the line at 70 feet. I prefer to be on my SS at that psi. I'm well aware that many divers will consider that wasted gas or sacrificed bottom time or whatever, but I consider it peace of mind...

800 psi at 70 feet on an ascent line is plenty of air to ascend, however leaving the bottom with 1100 psi does not bring me peace of mind.. I need pony bottle for that.

 

[I Dive]

800 psi at 70 feet on an ascent line is plenty of air to ascend, however leaving the bottom with 1100 psi does not bring me peace of mind.. I need pony bottle for that.

I think we are a mix of agreeing and disagreeing!

 

[DA Aquamaster]

800 psi in an AL 80 is 20.5 cu ft of gas.

Losing it all in 10 seconds is a flow rate of 123 cu ft per minute. That is a pretty impressive flow rate but is within the realm of possibility if the flow is just basically straight out a low pressure port.

It is enough to make you give pause. You either want a redundant air supply, a very reliable buddy or the ability to do a free ascent to the surface. The latter is not usually an option if you are anywhere near the NDL's as a 3 minute safety stop is more or less mandatory.