Getting my First Reg - Need Advice

[DevonDiver]

This is not a braided vs rubber hose issue, but rather a thermoplastic inner hose vs rubber inner issue.

Where both hoses (rubber and nylon-braided) have a PU inner, degradation of the rubber hose would be immediately apparent on casual inspection. The nylon braided hose wouldn't show the damage... and could be kept in use long after the inner layer had degraded catastrophically.

That's the big difference between nylon-braided versus rubber hoses.

The issue with nylon-braided is that the inner can degrade so extensively that gas flow down the hose becomes impossible at depth. However, that wouldn't be apparent at lower, or surface, pressure.

That's exactly what happened in the incident I experienced. Both long and short hoses had degraded catastrophically. A technical diving student couldn't access any gas beyond 18m depth. I had to share air to save life. The regs had been well inspected the day prior... we'd done surface and descent checks.... no issue was observed or evident until both hoses suddenly couldn't deliver gas at depth.

 

[george_austin]

My OE with Miflex is so bad I will never use them again. For me, most of my hp and lp Miflex hoses last 50 dives or less - then champagne bubbles followed immediately by larger and larger ones. I threw all of them away as unsafe at any speed

Lots and lots of money down the crapper

 

[Bierstadt]

Where both hoses (rubber and nylon-braided) have a PU inner, degradation of the rubber hose would be immediately apparent on casual inspection. The nylon braided hose wouldn't show the damage... and could be kept in use long after the inner layer had degraded catastrophically.

That's the big difference between nylon-braided versus rubber hoses.

The issue with nylon-braided is that the inner can degrade so extensively that gas flow down the hose becomes impossible at depth. However, that wouldn't be apparent at lower, or surface, pressure.

That's exactly what happened in the incident I experienced. Both long and short hoses had degraded catastrophically. A technical diving student couldn't access any gas beyond 18m depth. I had to share air to save life. The regs had been well inspected the day prior... we'd done surface and descent checks.... no issue was observed or evident until both hoses suddenly couldn't deliver gas at depth.

I think this is where I am confused: how would the damage be readily apparent with a rubber outer hose? If the hose construction was a single layer, sure, but while I have never cut one open my understanding is that it is composed of multiple layers. Given that the rubber outer layer and the thermoplastic inner hose experience very different stresses (direct exposure to cold breathing gas vs direct exposure to water), how does the condition of the outer rubber layer indicate the condition of the inner thermoplastic layer? Are they made out of the same material in every hose and affected by polymer crystallization in the same way and at the same rate?

I would not think so, but please correct me where my understanding is wrong.

 

[george_austin]

All of mine showed leaks at the fitting ends with bubbles exiting where the hose meets the metal. I haven't cut one up to inspect but I think I will

 

[Bob DBF]

Are they made out of the same material in every hose and affected by polymer crystallization in the same way and at the same rate?

I would assume, like any other material, how you use it and store it make a difference in it's failure. Also there were knockoffs made by other mfgs, but everyone called them Miflex, and their higher rate of failures made Miflex look worse. I don't need that flexable a hose, but if I did, I would make sure it is actually Miflex, and replace it on their recommended schedule.

Bob

 

[cerich]

I would assume, like any other material, how you use it and store it make a difference in it's failure. Also there were knockoffs made by other mfgs, but everyone called them Miflex, and their higher rate of failures made Miflex look worse. I don't need that flexable a hose, but if I did, I would make sure it is actually Miflex, and replace it on their recommended schedule.

Bob

Bull...in my experience, observations and testing I am very confident that most of the non miflex brand braided hoses do not have a higher failure rate. I am not convinced it isn't the other way around, however.
I have seen multiple reports of "generic" braided hose failures that are in fact branded miflex hose, including in Andy's article. I also am not aware of any countereit miflex hose on the market either.

 

[tbone1004]

there are only so many materials that they can use for these things and there is only so much quality difference in standard tubing. This stuff is not rocket science. They take a standard tube, and put it in an overbraiding machine and braid over. They can choose some different material qualities especially for the braiding yarn, but the interior side is going to be standard tubing.

 

[george_austin]

Holy hose failure, Batman
Just exactly how many miflex and or Miflex knock off failures have you seen? Sounds like an extremely frequent occurrence-
Where do they commonly fail? After how many times in use? Root Cause?

 

[tbone1004]

Holy hose failure, Batman
Just exactly how many miflex and or Miflex knock off failures have you seen? Sounds like an extremely frequent occurrence-
Where do they commonly fail? After how many times in use? Root Cause?

i've had 2 HP, and 5 LP failures since I got my first ones in 2010. Most all at the crimp. I haven't had any deteriorate on the inside, but I keep my stuff in climate controlled areas and out of the sun. If I'm not wearing the rig at the surface, it's covered in a towel to keep it out of the UV

 

[george_austin]

there are only so many materials that they can use for these things and there is only so much quality difference in standard tubing. This stuff is not rocket science. They take a standard tube, and put it in an overbraiding machine and braid over. They can choose some different material qualities especially for the braiding yarn, but the interior side is going to be standard tubing.

That's what I thought too. It's just braided yarn over a rubber hose with the swage fitting attached via hydraulic press (sic)??