O-ring/low pressure hose failure

[Freewillow]

I am not sure if this question is in the right section. If it is not, I hope that the moderator will help me.

I have a question that relates to the minimum of air one should have in order to resurface safelly with his buddy. Most "scholl of thought" would indicate that you need to calculate the amount of air that you need to safely surface ( including deco/safety stops ) for both YOU AND YOUR BUDDY. plus a certain reserve. Lets say 50 bars (700 PSI?).

My questions has to do with the frequency of medium pressure line failure during ascent wich is, in my opinion, the only real reason why you want to have air for your buddy ( appart from LOA which has nothing to do in this case). Correct me if I am wrong, my questions relates to tropical water so I guess that the elimination of uncontrolable free flow is reasonable . EXPERTS PLEASE CORRECT ME IF YOU THINK I AM CRAZY

For those, who have experienced a medium pressure line failure, could you tell me if this was: before the dive ( on the boat ) first 30% of the dive, second 30% of the dive, last 30% of the dive or during ascent/safety stops. Please consider dives in open water without cover. Cave or wreck diving is another matter where lines can be severely treated

Thank you.

 

[MXGratefulDiver]

I don't know about crazy ... but I'm having a difficult time understanding the logic in your comments. Why would you worry about a hose failure ... which has a lower percentage of occurring than you being struck by lightning ... while at the same time brushing off the necessity for reserving air for a buddy who might go LOA ... which occurs commonly, particularly among tropical divers.

Most freeflows are not going to be the result of a hose failure ... they're going to be the result of a first or second stage failure, either due to IP creep or simply a lack of servicing the reg properly (not an uncommon issue with rental regs) ...

... Bob (Grateful Diver)

 

[Freewillow]

Thank you NWgrateful diver. I am asking this question because I am diving MOSTLY alone with a friend, as 2 buddies. I have been diving with her for more that 25 years. The "usual" LOA is no option since we are monitoring BOTH jauges all the time. That only reason for me would be some kind of hose/o-ring failure. Please experts, I would be glad to be proven wrong -

This is the reason for my question.

finally can you explain IP creep and I do not use rentals.

 

[Steve_C]

apart from LOA which has nothing to do in this case

Why?

Example: For some reason your buddy gets nervous and his/her sac rate goes up. There are lots of ways this can happen.

A need for air is a need for air.

 

[MXGratefulDiver]

Simplified explanation ... IP creep is usually the result of wear on the high pressure seat in the first stage ... which results in a steadily increasing pressure being delivered to the second stage when you take a breath. Most second stages are designed to be optimally operated in the 120-140 psi range, and when the pressure from the first stage exceeds this it results in a free-flow. Often the first indication of IP creep is a slight bubbling in the second stage when you're not inhaling ... and this can sometimes be "resolved" by tightening the little adjustment knob on the left side of the second stage. But not all second stages have that adjustment ... and even the ones that do shouldn't rely on it as anything other than an early warning that your regulator is in need of servicing ... because it's highly likely that the problem's only going to get worse.

... Bob (Grateful Diver)

 

[Bob DBF]

I'm not going to play the poll, however the only catastrophic LP hose failure I've had was 45 or 50 years ago and involved an upstream second and and a first that failed with a high IP. It was a long time ago and I was a bit busy and had little interest in the particulars at the time.

This no longer happens because the vast majority of seconds now are downstream and freeflow as Bob has described if the IP rises, folks now put an over-pressure relief valve when using upstream seconds or use a downstream "safe second" as the relief. Over the years I have seen a lot of hoses in disrepair, but all leaked rather than failed. I have avoided those problems by monitoring the condition of my hoses and replacing hoses and o-rings as necessary.

It is better for you and your buddy to work up a gas management plan that will keep you both safe in any emergency rather than focusing on a problem that is not likely to happen.

NOTE: Just noticed you are in Brussels, Poseidon seconds are upstream regs so insure you have a pressure relief on your reg if you are using them.



Bob
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I may be old, but I’m not dead yet.

 

[ajduplessis]

No option for NEVER!!!!!

 

[macado]

I have had a LP hose failure on surface. It was not the result of an IP leak. To be honest it was completely my fault and preventable and I should have addressed it sooner. The outer rubber casing on the hose had started to crack and was showing heavy signs of wear but I kept telling myself "I would get one more dive out of it.." I don't recommend this for obvious reasons.

I don't use hose protectors on my hoses and the failure was due to the stress I had been putting on my LP hose because of the bend in it for my drysuit because of non-optimal hose routing. I have since put a angled port adapter on the hose to correct the issue and I inspect my LP hoses more regularly.

 

[MXGratefulDiver]

Had a LP host blow up like a balloon at the swage while on my Raja Ampat trip last year. Fortunately I was able to secure another LP hose to complete the trip, but while there was plenty of visual evidence of an impending failure, the hose never actually leaked, much less exploded ...

... Bob (Grateful Diver)

 

[Eric Sedletzky]

Just get your stuff serviced/inspected regularly and quit worrying about it.
Go dive and have fun.

If you're still worried about it then become the poster child for Scubapro's annual service FPFL program.
And while you're at it, have them change all the hose each year just to be safe.