Why It's Not A Good Idea To Use Hose Protectors!

[Absolutbill]

I pull my hose protectors back after a dive to rinse out the salt. Ten I apply a little silicone around e end of the hose to protect the metal and allow the protector to slide back and forth for an easier inspection before the next dive.


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[GrumpyOldGuy]

"From outside appearances the hose was fine". So just how did the hose protector interfere? What would you have expected to see without the protectors installed?
Most LP or HP hoses fail from the inside. The rubber on the outside can crack but the hose won't leak unless the inside hose is breached. By the same token the outside rubber hose won’t contain the pressure if the inside hose is breached. I’ve used hose protectors for decades without incident. I listen for leaks before a dive. Looking at the hose to detect a leak is dubious.
Your car’s rubber brake lines are constructed in a similar fashion.

Respectfully, the hose design needs both the inside and the outside to be in good shape to maintain its original rating. Cracks on the outside may not be enough for a failure by themselves, but are a big clue the hose has been stressed beyond its design and may have internal damage, all before it starts to leak. Unlike a brake lines in a car that is firmly anchored in a single position on both ends, our hoses are anchored at one end with the other subject to random forces and some abuse that does tend to manifest its presence at the anchored end. Exactly the reason for hose protectors, they just have an undesirable side effect of hiding the damage if they are not effective in their job.

Hose wraps and braided covers add even more fun to the game.

 

[muzikbiz22]

I know exactly what caused it. I was using a 28 inch hose which was just a bit too short for my sidemount configuration. The hose was getting pinched off under the protector and I didn't realize it. With over 100 dives on that hose I guess it was only a matter of time. I now have a 30 inch hose which works perfectly.

Not trying to be sarcastic here, but it sounds like this was your fault, (hose too short) and had nothing to do with a hose protector ??? OPINION ALERT - A hose protector could have prevented this exact thing from happening. FWIW, I have them on all hoses. My main LP reg not only has a protector, but that hose is a MiFlex hose. I'm guessing about 600+ dives, lots of travel, etc., with that one hose and protector, NO ISSUES. I do slide back from time to time to inspect, and have never had an issue with corrosion either.

 

[Hatul]

This picture shows why it is not a good idea to have hose protectors on your regulator hoses. You cannot clearly see if any damage has been done to the hose. This LP hose blew on me at the end of a cave dive. We had just finished a very long cave dive complete with saftey stop and literally as my head broke the surface of the water, kaboom LP hose explosion. I've never seen air escape so fast. If it had to blow this was the perfect time for it to go because this could easily have happened at our max penetration and we were pretty far back into the cave. I am sure I have dive angels watching over me. I probably would have been OK since I was sidemount and still would have had the reserve of one tank and the ability to feather the valve of the bad tank but it would not have been a fun experience for me or my buddy. In OW this would have most likely been an air sharing event. At no time during the dive was there any sign of hose issues, not even a bubble. From outside appearances the hose was fine. If I had to take a guess I'm guessing the pressure at depth had something to do with preventing the hose from blowing but as soon as the pressure was released by surfacing the hose blew.

DSCN02341 - - ScubaBoard Gallery

I thought you were going to show hidden corrosion, but your photo makes a case for hose protectors. There is no doubt that they decrease the mechanical stress at the crimp, which is what caused the failure. The lesson is to pull the protector back after the dive to let the area dry and to inspect the hose, then push the protector forward to do it's job.

Having said that, the new braided low pressure hoses do not come with hose protectors. My Atomic traditional hose comes with a protector that easily slides for inspection.

 

[AfterDark]

Respectfully, the hose design needs both the inside and the outside to be in good shape to maintain its original rating. Cracks on the outside may not be enough for a failure by themselves, but are a big clue the hose has been stressed beyond its design and may have internal damage, all before it starts to leak. Unlike a brake lines in a car that is firmly anchored in a single position on both ends, our hoses are anchored at one end with the other subject to random forces and some abuse that does tend to manifest its presence at the anchored end. Exactly the reason for hose protectors, they just have an undesirable side effect of hiding the damage if they are not effective in their job.

Hose wraps and braided covers add even more fun to the game.

Agree. However have someone turn the wheels on your car and watch the brake hoses, the amount of movement might surprise you.
Bottom line in the case of the OP it seems like no outside damage was evident.

 

[CT-Rich]

The fact that this happened at the surface was probably a fluke. Regulators supply air relative to ambiant pressure, so depth should have been a negligible factor. My guess is that even if you did look at the hose before the dive, you would not have seen enough to be concerned about. It might have had a slight bulge, but I think once air started leaking into the outer layers of the hose, the failure developed quickly. from the condition in the picture, it looks like the failure was from the inside out. the hose doesn't look like it was showing external wear. You might take a look at how you were handling the gear. Caving means a lot gear and if tanks were piled on other gear it could have creased the hose. I am not saying that is what happened, but it might be worth thinking about. You might also want to check with the manufacturer maybe it was a defect on thier end.

 

[Steve_C]

Have replaced hoses three times. In all three cases weakness was only apparent with a full tank and tank submerged in water. Importance of bubble check at start of dive. Nothing showed up on visual nor at end of dive. Leak always at clamp. They are HP tanks.

 

[DA Aquamaster]

As Rich notes above, intermediate pressure is constant above ambient pressure, but that assumes you were breathing off the reg.

Assuming you were breathing off the other regulator, the un-used reg, assuming a normal IP of 140 psi at the surface, would have had a pressure of about 170' psi (140 psi, plus about 30 psi for the depth). Normally, as you ascend the IP drops again, provided the reg is being used and the air in the reg has somewhere to go, so when the reg is in use, the IP stays pretty constant at 140 psi above ambient. However if it is not used (either for breathing or inflation) then the IP can be above ambient pressure as the air in the first stage will not just go back in the tank. Once it gets high enough it will vent through a second stage or OPV, but on most balanced second stage regs, you'd need an IP of around 170 psi to 190 psi for the excess pressure to vent.

So it's possible, depending on depth/dive profile, type of second stage, and whether the reg was used on ascent, that Tracy's reg could have had an internal pressure that was 30-50 psi over the normal ambient pressure when the LP hose failed.

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I'm also in the camp that hose protectors do more harm than good. To be truly effective at preventing overly sharp bends, they have to be stiff, and if stiff they are very difficult to slide back to inspect. So, they either don't get inspected or the hose gets stressed when the diver pulls on it to slide off the hose protector. And of course if they are stiff enough to support the hose, they are generally not self draining so the fitting does not get rinsed and corrosion occurs. On the other hand, if the hose protectors slide off easily (Scubapro hose protectors for example) they make inspection very easy and the design makes them easy to rinse, but they don't do all that much to protect the hose from excessively sharp bends.

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Hose inspection is always a good idea and bubble checks are a integral part of that, but it's not always going to show an incipient failure. I had a 6" SPG hose (not miflex) fail after surfacing from a cave dive at JB, and replaced it only to have the other 6" hose on the other reg fail while gearing up for the very next dive that same day when the reg was pressurized. They literally both failed at opposite ends of the same surface interval. Both hoses looked great, with no visible wear damage, bulges or bubbles, were only about a year old, and were not bent at sharp angles in use.