HP Hose Failure

[Tanks A Lot]

[...]
Now compare the same 150 psi hose maximum working pressure with that of the older SAE standard that although working at the same 150psi pressure the old specification had a maximum allowable working pressure of 1250 psi together with a burst pressure of 5000 psi. This gives a safety margin of 4:1 Four time the maximum allowable working pressure before burst. More than the full working pressure of the cylinder.
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EN250 by contrast is nothing like up to the same standard. You print the working pressure on your toilet water pipe hose and the words EN250 and you're done.
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I just want to point out that this is factually wrong. EN250 includes the same 4:1 safety margin as comparable SAE standards.

Under EN250 for HP-hoses:

• Unpressurized tensile force of 1000N
• Flexibility test around a 65mm (±2.5mm) cylinder
• Withstand four times working pressure (Burst test)

Under EN250 for LP-hoses:

• Unpressurized tensile force of 1000N
• Flexibility test around a 65mm (±2.5mm) cylinder
• Endure at least twice the rated pressure or 30bar, whichever is higher
• Withstand four times working pressure or 100bar, whichever is higher (Burst test)
• Resist kinking
• Axial tensile load of 250N on the connections for breathing hoses

I omitted a few other requirements for brevity.

Ian is right to point out that SAE J517, which includes the earlier-mentioned SAE 100R3 and SAE 100R8, is a bit more specific. It goes into more detail about what materials to use, but that is often done to ensure that the chosen material is compatible with hydraulic fluids. The SAE tests are a little more rigorous, but again, I’d argue that this is due to the environments they are expected to operate in. I see little reason to make a SCUBA hose endure an impulse test, for example. In a hydraulic system, on the other hand, this is most beneficial. The other tests are virtually the same or irrelevant.

Making a hose pass a test, be it EN250 or SAE J517, and last for a couple of years is simple. Making them last decades is hard. It doesn't matter if it's a hose or another item; bad quality is bad quality. But this has nothing to do with the standard itself.

I also find it disingenuous to pound on the fact that EN250 hoses should be replaced at certain intervals. EN250 itself doesn't specify anything like that. It’s mostly the manufacturers doing so. If I recall correctly, SAE J1273 specifically outlines a 10-year lifespan for hydraulic hoses from the date of manufacture, provided they pass regular visual inspections.

Comparing SAE J517 with EN250 is like comparing apples to oranges. One is expected to withstand hydraulic oils and fluids, while the other must contain gas. SAE 100R8, for example, specifically aims at producing non-conductive hydraulic hoses. This is irrelevant to SCUBA.

That there is a certain lack of oversight and enforcement of the rules and requirements is no doubt true. No one stops a dubious character from making substandard hoses, stamping EN250 onto them, and selling them in the EU. But that doesn't mean the standard itself is flawed. Equally, the same people can sell substandard SAE 100R8 hoses.

I don't agree that EN250 hoses are all rubbish. Sure, there are bad hoses under the EN250 umbrella, but so are there under SAE J517. In my opinion, EN250-compliant hoses from a reputable manufacturer are well suited for the SCUBA market and I see little reason to suggest otherwise.

 

[iain/hsm]

I just want to point out that this is factually wrong. EN250 includes the same 4:1 safety margin as comparable SAE standards. Under EN250 for LP-hoses: Endure at least twice the rated pressure or 30bar, whichever is higher
Withstand four times working pressure or 100bar, whichever is higher (Burst test)

Heck busted LOL....No.... But now I have to point out in reply that your statement quoted above is factually misleading and convert Bar to Psi by the look of it. But your statement is still misleading and EN centric if you dont mind me saying. But they are two vastly contrasting standards.

1. Under EN 250 the LP hose is tested to 30 Bar (435 psig) and withstands 100 Bar (1450 psig)

Now contrast that to the original American Diving Hose LP standard SAE100R3 DIVERS HOSE
and please note this is not the same as SAE100R3 Hydraulic hose as you implied.

2. Under SAE100R3 Divers Hose The minimum working pressure is 86 Bar (1250 psig) and the minimum test burst pressure is 345 Barg (5000 psig)

We Agree so far? Yes.

Therefore by our agreed calculation the American SAE100R3 Divers Hose is four times that of the EU250 standard for there junk toilet water hose that was introduced into the EU market by the vested interest parties of the various committee members in order to introduce the cheap junk from China et al and the multiple recalled toilet water hose from Italy. This is when the first misleading fudge of 4:1 is introduced to the unsuspecting scuba diving market together with pretty colours matching options.

We still agree?

While the Americans scuba divers were simply sold down the river with the plethora of junk made for profit trinkets and the original American standard dumped in favour of this inferior EU junk.
Others may disagree. Feel Free. But one of them is tested to 30 bar while the other is happily working at 86 bar. And to put it another way one withstands 1450 psi while the other 5000 psi and were only starting by talking low pressure 10 bar (150psi) intermediate hose.

 

[Divin'Papaw]

Heck busted LOL....No.... But now I have to point out in reply that your statement quoted above is factually misleading and convert Bar to Psi by the look of it. But your statement is still misleading and EN centric if you dont mind me saying. But they are two vastly contrasting standards.

1. Under EN 250 the LP hose is tested to 30 Bar (435 psig) and withstands 100 Bar (1450 psig)

Now contrast that to the original American Diving Hose LP standard SAE100R3 DIVERS HOSE
and please note this is not the same as SAE100R3 Hydraulic hose as you implied.

2. Under SAE100R3 Divers Hose The minimum working pressure is 86 Bar (1250 psig) and the minimum test burst pressure is 345 Barg (5000 psig)

We Agree so far? Yes.

Therefore by our agreed calculation the American SAE100R3 Divers Hose is four times that of the EU250 standard for there junk toilet water hose that was introduced into the EU market by the vested interest parties of the various committee members in order to introduce the cheap junk from China et al and the multiple recalled toilet water hose from Italy. This is when the first misleading fudge of 4:1 is introduced to the unsuspecting scuba diving market together with pretty colours matching options.

We still agree?

While the Americans scuba divers were simply sold down the river with the plethora of junk made for profit trinkets and the original American standard dumped in favour of this inferior EU junk.
Others may disagree. Feel Free. But one of them is tested to 30 bar while the other is happily working at 86 bar. And to put it another way one withstands 1450 psi while the other 5000 psi and were only starting by talking low pressure 10 bar (150psi) intermediate hose.

So this explains why all of my junk hoses keep exploding on me after a year or two of use. Oh wait ....

 

[BoltSnap]

So this explains why all of my junk hoses keep exploding on me after a year or two of use. Oh wait ....

And the world is ending, and all hoses were hosed with the sky falling and raining hosed hoses on us.

 

[iain/hsm]

I omitted a few other requirements for brevity.

Ian is right to point out that SAE J517, which includes the earlier-mentioned SAE 100R3 and SAE 100R8, is a bit more specific. It goes into more detail about what materials to use, but that is often done to ensure that the chosen material is compatible with hydraulic fluids. The SAE tests are a little more rigorous, but again, I’d argue that this is due to the environments they are expected to operate in. I see little reason to make a SCUBA hose endure an impulse test, for example. In a hydraulic system, on the other hand, this is most beneficial. The other tests are virtually the same or irrelevant.

Point 2. Taking an international recognised worldwide standard and adapting it for our specific underwater breathing application was easier than starting another new one from scratch.

Taking your specific point about "environmental conditions they are expected to operate in."
Again please note carefully that not all Divers hose is for recreational diving applications
other considerations such as diving in an oil slick, jet fuel, bunker oil and the like as well as industrial offshore diving and other black water and contaminated water considerations were in play at the time.

It is not fair for example for you to suggest that a hydraulic fluid medium was a consideration.
Adopting the standard is the point hence you see SAE100R3 Divers Hose. added and printed on the tubes. A valid traceable recognised and easily validated specification was pushed under the bus for junk.

 

[iain/hsm]

I also find it disingenuous to pound on the fact that EN250 hoses should be replaced at certain intervals. EN250 itself doesn't specify anything like that. It’s mostly the manufacturers doing so. If I recall correctly, SAE J1273 specifically outlines a 10-year lifespan for hydraulic hoses from the date of manufacture, provided they pass regular visual inspections.

I fully agree we are now in the hands of Brand sales and marketing and the dive shop
Frankly I don't think the majority of average PADI scuba diver today lasts 10 years
And judging by some of the recent one liner replies the rest are far to ignorant for anyone to care

Although we still don't know the resolution made to resolve the LP recall fiasco or the HP hose
or the claimed 30 odd tests Miflex were apparently required to undertake.

I agree 10 year life is about right with a regular visual. On a side note the Royal Navy has a long term storage trial on the military Clearance Divers Breathing Apparatus I think its at 30 years now and still counting as no one is bothered to stop it or can remember it by now. All carefully wrapped and packed and fully SPIS packed for WW3

 

[Tanks A Lot]

Maybe I should have been clearer with the distinction between burst pressure and leak pressure. I see that putting burst test in brackets wasn't clear enough, apologies. I also do not see how you can think I made an error from bar to psi, EN250 is fairly straightforward.
From EN250:

5.8.6 Burst pressure of medium pressure hose assembly
Any medium pressure hose assembly shall withstand four times the rated working pressure or at least 100 bar, whichever is the higher.
There shall be no burst.
Test in accordance with 6.5.7.

5.8.4 Leakage of medium pressure hose assembly
Any medium pressure hose assembly shall withstand twice the operating pressure of a safety valve or at least 30 bar, whichever is the higher.
There shall be no leakage.
Test in accordance with 6.5.5.

This is the first time I have heard of a SAE100R3 divers hose. SAE-J517 lays out hydraulic hoses, one of which is the SAE100R3 standard. I can't find any mention of a 100R3 hose specifically aimed at divers or any other breathing scenario, not in the current standard nor in historical context. Would you mind elaborating where it is specified? I'm not being smug here, but genuinely would like to read the standard for it.

Otherwise I assume you reference a 100R3 SAE dash-size 4. This hose has a nominal inside diameter of around 6mm to 7mm which would closely put it to a standard SCUBA hose. This hose is indeed rated to 87bar and has four times the burst pressure.

You further mention that not all diving is done in clear water, which is fair enough. Yet, most people that are buying hoses for recreational purposes will care little about the chemical resistance of their hose.

There is no disagreement that a SAE 100R3 dash-size 4 hose is sturdier than a EN250 hose. But I take issue with the statement that the EN250 is wholly inadequate for the SCUBA sector, especially when thinking about the recreational sector.
The dash-size 4 is sturdier, but why stop there? Why not take a SAE 100R11 dash-size 4? It has the same diameter as the puny 100R3 and is able to withstand 780bar with a burst pressure of 3120bar. Surely the 100R3 #4 is a toilet-hose compared to the mighty 100R11 #4.

There is always a cost-benefit analysis to be done. In my view, the EN250 hose is good enough for the job intended, just like my 1988 Ford Fiesta is good enough to drive me from A to B. No doubt, a new Mercedes Benz will do it faster, safer and in more comfort, but outright saying that the Fiesta isn't capable of the job I ask it to do is disingenuous.

 

[Eric Sedletzky]

And the world is ending, and all hoses were hosed with the sky falling and raining hosed hoses on us.

Yeah, I think we got hosed!

 

[iain/hsm]

SAE 100R8, for example, specifically aims at producing non-conductive hydraulic hoses. This is irrelevant to SCUBA.

I would urge you to reconsider this position.

For any diving with any breathing gas the introduction of a non conductive
core offered a huge advantage and a solution for as you put it earlier using an industrial hydraulic oil standard and the reason to alter the original R3 hydraulic oil standard for Diving use.

A non conductive core for a high pressure oxygen is agreed by all for oxygen use. But it is more than that

1. The lack of particulate contamination.
2. The requirement to "Pig" the hose" Fire a white clean fibre wad down the length
to check and to "particle count" any contamination.
3. The requirement for the use of special oxygen compliant lubricating oils and grease allowed in the assembly of the end fittings.

As well as the packing and wrapping end caps etc
The standard of SAE100R3 Divers Hose was also to precluded any cheap hydraulic supplier or importer.
without valid assurance that the required standards for Diving Hose were met.

 

[rmorgan]

Not to be mundane . . . I had one of the standard 6” AI transmitter standoff HP hoses develop a large (~1/2”) bubble and smaller bubbles after maybe 18 months of use. We’ve stopped using them—I liked having the seeming protection against the transmitter being used as a handle, but not the idea of a short HP hose I couldn’t reach exploding next to my ear and draining my gas—much less adding two possible failure points to the kit. I don’t know whether it would have progressed to catastrophic failure, but it seemed likely.