HP Hose Failure

[iain/hsm]

Be real. It was calculated to insult.

I'm still waiting for some figures and studies to back up your contentions.

Try calling me (quote) "you just can't let go of being a jackarss". post 27
or this (quote) "Aside from your usual incomprehensible ravings", post 13
Again and see what happens. But for now I repeat.

My replay was calculated balanced and sufficient in response.

Besides the level of technical information given alone so far should offer a clue as to the
level of information required to make an informed comment. Despite attempts to skewer the
thread.

 

[davehicks]

I love the clash of philosophies, but didn't expect to ignite a holy war over high pressure hose construction and value. Let's put away the spec sheets and move on to the next thing!

 

[The Chairman]

Besides the level of technical information given alone so far

No figures to back up your assertions so far. None. Nada. Squat. It's not rocket science: it's a hose. You even assumed it was made in Asia because it failed. All hoses will fail.

 

[The Chairman]

I love the clash of philosophies, but didn't expect to ignite a holy war over high pressure hose construction and value. Let's put away the spec sheets and move on to the next thing!

It's the split-fin effect. Posters claim expertise sans figures and studies. If you don't agree with them, you will surely die. Meh.

 

[iain/hsm]

It's the split-fin effect. Posters claim expertise sans figures and studies. If you don't agree with them, you will surely die. Meh.

With that comment above your frankly fudging it mate and have got yourself into a position you may find difficult to recover from.

Look I don't want a fight or some big showdown and I certainly don't want to start listing my experience in diving equipment but suffice to say stick around I like nothing more than to explain things fully and in detail in the hope fellow divers will understand in an attempt to educate and pass on valuable pieces of detailed information by which younger divers can make an informed choice.

I can pass on knowledge freely and easily, experience however you will have to glean for yourself .

 

[davehicks]

What might actually be useful to others would be a recommended shopping list of hose vendors. What to buy and where to buy it. Just telling everyone that there is a lot of substandard gear on the market is not actionable.

 

[iain/hsm]

I love the clash of philosophies, but didn't expect to ignite a holy war over high pressure hose construction and value. Let's put away the spec sheets and move on to the next thing!

Me too by the sound of things. LOL. But we are way past Kansas now on this yellow brick road.

Incidentally that excellent photo you published in post 1 needs some explanation.

Look carefully at the metal end fitting note the domed metal riser just in front of the crimped part that crimps down onto the rubber hose. This dome is to allow the compressed end of the rubber and fibre reinforcement cover of the inner hose to squeeze out and up into the dome. While sealing the inner hose end against the internal barbed quill. This is to avoid the compression forces of the hydraulic crimping dies cracking of the metal outer sheath against the non compressible metal inner Quill.

Now note its not the same type of connection as you see on a high pressure hydraulic hose (crimped) or a high pressure gas hose (pallet swaged) and is more typical as the type used on low or medium pressure hose. The failure here is that gas escapes past the inner hose into the void space dome then down the fibre or textile braiding and out under the inner sheath. This gas then expands and leaks past what is called a pricked outer sheath and causes the bubbles.

From the photo bubbles are escaping down pretty much the entire length of the hose and would suggest it's a crimp end attachment failure rather than a burst inner tube. Hence my earlier comment on professional diver hose requirement for a designed pull test requirement of professional divers hose as opposed to this recreational EN 250 scuba junk.

Occasionally on old bell umbilicals using similar type hose a leak can cause as a blister on the outer sheath normally caused by helium leaking across the the fibre this by contrast is always a single blister and is commonly pricked while the bell umbilical is being recovered with the bell into its basket.

Technically the definition for a burst hose you end up with two separated parts or a a loss of the hose out of the metal end fitting or a partial separation of the hose mid point. In your case it's really classed as a rapid event leak the cause of which would be pretty interesting to evaluate together with the other stuff we need to address. I enclose your photo again for ease of reference.

 

[The Chairman]

I can pass on knowledge freely and easily, experience however you will have to glean for yourself .

I'm new to this sport. I only started in 1969 using a healthways regulator. I've been an instructor since just after the turn of the century. I've worked in shops, rebuilt more regulators than I could care to count, and have replaced more than my share of hoses. I'm sure that pales in comparison to your experience.

Just telling everyone that there is a lot of substandard gear on the market is not actionable.

It's not meant to be. It's almost entirely ego driven and relies on fear mongering. They think they know better, but somehow can't be bothered to clue you in their "secret sauce". Some feel that dissing products elevates their standing in the eyes of others. Maybe some are gullible enough to think they are on to something, but there just any substance to their cries of alarm. In the end, the gear produced today is far superior than when I first started diving... even the hoses. Plan on replacing your hoses from time to time. Look for checking in the outer cover, and chuck those that show signs of deterioration. Most diving destinations have hoses available should one decide to fail on a dive. If a hose does start to fizz, check your air and call the dive. If it's a really big leak, like an o-ring failure, kink the hose if possible and call the dive. It can be quite an exciting experience, but in over 50 years of diving, I can't think of a single injury, much less death attributed to a failed hose.

And please, many leaky hoses look just like good hoses. Make a habit of cutting leakers into two pieces. Snip, snip. That will stop anyone from accidentally reusing it.

 

[Eric Sedletzky]

I'm new to this sport. I only started in 1969 using a healthways regulator. I've been an instructor since just after the turn of the century. I've worked in shops, rebuilt more regulators than I could care to count, and have replaced more than my share of hoses. I'm sure that pales in comparison to your experience.


It's not meant to be. It's almost entirely ego driven and relies on fear mongering. They think they know better, but somehow can't be bothered to clue you in their "secret sauce". Some feel that dissing products elevates their standing in the eyes of others. Maybe some are gullible enough to think they are on to something, but there just any substance to their cries of alarm. In the end, the gear produced today is far superior than when I first started diving... even the hoses. Plan on replacing your hoses from time to time. Look for checking in the outer cover, and chuck those that show signs of deterioration. Most diving destinations have hoses available should one decide to fail on a dive. If a hose does start to fizz, check your air and call the dive. If it's a really big leak, like an o-ring failure, kink the hose if possible and call the dive. It can be quite an exciting experience, but in over 50 years of diving, I can't think of a single injury, much less death attributed to a failed hose.

And please, many leaky hoses look just like good hoses. Make a habit of cutting leakers into two pieces. Snip, snip. That will stop anyone from accidentally reusing it.

I've only seen one HP hose blow out when pressurized and it was a short one on a stage bottle. It sounded like a shotgun went off. Enough so that the Sheriff showed up to the boat launch parking lot where it happened. BTW, it wasn't mine, it was actually a tech instructors who had a habit of reusing very old hoses and couldn't throw anything out.
On another note, my dive shop frequently gives me old hoses both LP and HP that I cut up and use for rail edge/tank protectors on my plates. I cut a slit
lengthwise down the sides to the center then slip the hose over the rail edges. I noticed on several occasions that the inner liner material on some hoses were crusty, almost like the inner liner material crumbed into chunks as I opened it. The material was tan in color. This was on LP hoses.
I have no idea what could cause this other than high concentrations of O2 perhaps, IDK? We don't have a tech community here, and vacationers using 32 or 36 at some resort might responsible but IDK. There is no nitrox available where I live unless you make your own.
HP hoses are much tougher and the hole is small. There's a kevlar weave in the outer layers. Gardening clippers get through it pretty easy.
I have never seen the inner most material on an HP hose deteriorate like what I've seen on LP hoses.

 

[iain/hsm]

What might actually be useful to others would be a recommended shopping list of hose vendors. What to buy and where to buy it. Just telling everyone that there is a lot of substandard gear on the market is not actionable.

I thought I did.
No matter to kick things off enclosed the SAE basic detail of the various hose specifications

1. Note the Gates SAE 100 R3 for intermediate regulators 1st stage to second stage has working pressure (over ambient ) of around 150 psi and the hose internal diameter is typically 0.250" 1/4 inch.

Note also the two textile braids and the maximum approved working pressure of 1250 psi with a burst pressure being a minimum four (4) times that at 5000 psi. This is known as a 4`:1 safety ratio from working pressure to burst and is to the military and professional diving a recognised standard within a required 3 inch bend radius.

The other gates hose is the high pressure hose for compressors etc the spec is SAE100 R8 note again for a 0.250 internal 1/4 inch bore the working pressure 5000psi with a minimum burst pressure of 4 times that at 20,000 psi albeit in practice on larger flow requirements a 3/8 bore may be adopted or for divers submersible gauges a smaller 3/16 or smaller bore hose is used

For reference the 3/8" umbilical hose

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