Strange bubbles

[data790]

Hi, new here and not sure if this subject has come up before but... I was diving today in Bergen at a usual site when I noticed on my pre-dive checks some small bubbles coming from my gauge combo hose. Closer inspection showed small holes equally distant apart. Now, these holes have to be man-made but why are they present? Has anyone else seen this in their combo gauges. Should I be concerned and replace the hose?

I have a suunto combo if that helps.

[Tristan Green]

It sound's like your high pressure hose is leaking and will need replacing. The purpose of the small holes in the outer sheath of the hose is to release the leaking air without causing a rupture of the hose.

Cheers,
Tristan

[N2-UK]

Holes in outer casing to allow for expansion and trapped air to escape. It may not mean anything more......

We have one Oceanic unit that does it occasionally, and one of our suunto combos. The thing is, you never see it unles the hose is wet.

[data790]

OK, I did keep an eye on my gauge and saw the air go down slowly - as would be expected - but I dove anyway and decided to make the dive a salvage for scallops and anything else tasty I could get my hands on, and did a 38 min dive to check my air usage. Nothing seemed out of the ordinary on my air usage, but it did make me wonder but not to the extent of my life in danger.

On a side note, has anyone dove or is planning on coming over to Bergen to dive? If so give me a bell as I am always diving here and have some excellent spots for deep and shallow dives.

Thanks for your help guys

Marc

[ChristianG]

Holes in outer casing to allow for expansion and trapped air to escape. It may not mean anything more
Really? Truly? You may well be correct bit it's not something I've heard of before.

[ChristianG]

OK, I did keep an eye on my gauge and saw the air go down slowly - as would be expected
Otherwise inferring that there may have been some kind of leak?

[data790]

Otherwise inferring that there may have been some kind of leak?


This is the strange thing. Yes it does assume to be leaking, yet the perplexing issue was these small holes. It was the first time I had noticed so did make me wonder. Guess it is best to replace rather than sit it out and wonder. Annoying to say the least since the nice weather has finally come. Happily it doesn't seem to be an expensive job if I can get the PADI dive centre to do a confident job :)

[Ron MacRae]

This is the strange thing. Yes it does assume to be leaking, yet the perplexing issue was these small holes. It was the first time I had noticed so did make me wonder. Guess it is best to replace rather than sit it out and wonder. Annoying to say the least since the nice weather has finally come. Happily it doesn't seem to be an expensive job if I can get the PADI dive centre to do a confident job :)

If there are bubbles comming out it's leaking.
My worry would be that the leak might become suddenly worse.
Remember this is the HIGH pressure hose.
Although the hole at the 1st stage end is small, to slow down a rapid escape, the hose is still at up to 300 BAR.
Replace the hose.

It's not complex/expensive.
It will take 5 mins with the correct set of spanners.
My LDS changes the cable for free, or if I don't have time to wait I do it myself when I get home.

Ron.

[ChristianG]

This is the strange thing. Yes it does assume to be leaking, yet the perplexing issue was these small holes.
I'd say that they are the commonly made holes when there is an HP leak - that doesn't act like a blowhole. Those "regular" holes that you see - aren't made by us hooman beans. Nor are they in fact "regular". I'd call them the "leaks" made when an HP hose gives out quite gradually. That's when the gas travels along the length of the hose until it finds the place of least resistance.

What concerns me more is the length of time you've actually used this hose.Was it new when you started? Alternatively, do you know when it was new - any idea of how often used?

HP hoses perform a very basic function - yet they are HP. I don't consider the failure of an HP hose (it happens rarely) to be a big deal even though some seem to think otherwise.

[N2-UK]

Really? Truly? You may well be correct bit it's not something I've heard of before.


Just measured on the Oceanic 'cos it was nearest to hand.

One clearly visible pin hole mark every 26mm, all the way up.

Don't know where the air that gets behind them comes from. This one had a 'lil bit of froth coming out of a couple of holes one dive early in our last holiday in Egypt, then never did it again.

And won't do it now either.

Go figure.

[data790]

They are about 8 years old maybe. I use them three times a week roughly - when I can get time to wonder down to the fjord. Best bet is to replace them. Think all this moving from uk to Norway, and moving from hedmark to Bergen may have not done them any good. Well I guess a full service also wouldn't go a miss while replacing the hose.

But those holes are equally spaced apart. I shall put up some pics if it helps. But my decision is to replace the hose. I like to keep as much air as possible for me... the fish get enough

[Nigel Hewitt]

This is how high pressure hoses go.
The gas penetrates the inner pipe and the outer layer is just backing to contain the inner and you get a line of bubbles normally six inches or more long.
If the outer layer could contain the pressure you wouldn't need the inner layer so the holes seep enough gas to stop it going bang.

Well that's the theory. Sometimes they just go bang.
It's history.

[Tristan Green]

Those "regular" holes that you see - aren't made by us hooman beans. Nor are they in fact "regular".
Take a close look at your HP hose. Every HP hose I have seen has these relief pin holes every inch of so down the length of the outer sheath. You are correct that the holes aren't made by 'human beings' only in the sense that the hose is not made by human beings - rather the holes are made by the clever machine that manufactures the hose.

As said earlier - buy a new hose the old one is knackered. Then chop the old one open and you'll see how the hose works - there is usually an inner air tight hose, surrounded by a plaited fabric (to contain the pressure in the inner hose, all surrounded by the outer sheath - you will see that the outer sheath doesn't contain the air or the pressure it is simply a protective layer the prevent damage to the bits inside that are doing the work of keeping the high pressure air in.

Regards,
Tristan

[data790]

This is how high pressure hoses go.
The gas penetrates the inner pipe and the outer layer is just backing to contain the inner and you get a line of bubbles normally six inches or more long.
If the outer layer could contain the pressure you wouldn't need the inner layer so the holes seep enough gas to stop it going bang.

Well that's the theory. Sometimes they just go bang.
It's history.

So the idea is to replace the hose or assume too much pressure got in and the hose just vented a bit off?

I started with 220 bar in a 12 ltr and prior to dive had 210. don't you just love it when things just go this way.

[ChristianG]

So the idea is to replace the hose or assume too much pressure got in and the hose just vented a bit off?
Yes, and no, in that order of your question.

The hose is kaput, knackered, about to go bang in the night, leaking, no longer an efficient unit, to be replaced before your next dive (with due apology to - and acknowledgement of - those gentlemen purportedly from Yorkshire).

[ChristianG]

(with due apology to - and acknowledgement of - those gentlemen purportedly from Yorkshire).
Aka Monty Python (http://www.youtube.com/watch?v=npjOSLCR2hE).

There now, just maybe I have a sensahuma after all. :o

[Nigel Hewitt]

So the idea is to replace the hose or assume too much pressure got in and the hose just vented a bit off?
As Christian says it is now junk. The inner has ruptured and it won't get any better, the next thing it does is blow a bubble in the outer and then it goes bang.

If you were away on a diving weekend it would probably see you through but I'd replace it on getting back near a shop even if it was a distance. If it was near the beginning of a week away I'd start asking round to see if anybody had a spare. Well I wouldn't actually because I'm the guy with the spare.

[Richard Whitcombe]

New hose time. The integrity of the inner hose has gone so its safely venting through the relief holes in the outer to stop it going bang.

[Mike Halligan]

So the idea is to replace the hose or assume too much pressure got in and the hose just vented a bit off?

Yes, replace the hose. It is finished.

If the hose wasn't so old, you should see a pressure rating greater than that of your cylinder printed several times along it. There is no possibility of "too much pressure venting into the wall of the hose". Think of the tyres on your car, inner wall, steel brace, outer wall. There, a duck-egg means BIG trouble, same as. :eek:

I started with 220 bar in a 12 ltr and prior to dive had 210. don't you just love it when things just go this way.

Well, leaving it pressurised unnecessarily does add to wear on the hose. In particular, leaving it pressurised with the gauge/computer raised from the deck or ground (to avoid crunching underfoot by some rather large and therefore carefree diver?) adds very significantly to wear on the hose. Believe me, I've had these hoses and I've replaced them after about 2 years. (I guess it's one reason why they developed transmitters.)

I've also had a mid-pressure direct-feed blow underwater, and that was interesting. It is alleged that this empties your cylinder faster than a HP hose blowing. (I didn't hang around to argue the point.) :D :D

[data790]

I left it this time to see if the pressure did fall. But I have stopped any other dives until I have replaced the hose and done some other repairs on the drysuit.

Hate not diving. The girlfriend prefers it if I don't, but I am planning on getting her a course with the PADI centre in a few weeks then we can go find that ww2 plane in Narvik around August.

Thanks for the advice, anyone ever fancy a trip over to Bergen let me know as any diving is good and diving with Brits would be nice again. Norwegians tend to moan a lot about the viz and cold water - no idea why, the viz is perfect when you can see past the jellyfish swarm lol.