pinholes in HP hoses

[marku]

I'm sure somebody has asked this question before, but I missed that thread. Sorry.

What exactly are those pinholes in HP hoses for? Some say that they're there to relieve over-pressurization, and yeah, tiny streams of bubbles occasionally do come out early in the dive. But aren't HP hoses rated up to 5000psi? They shouldn't have any trouble keeping 3000psi of air in, shouldn't they?

I don't mind having bubbles come out from my 1st stage or from my valve-1st stage interface, but I'm kind of paranoid about bubbles coming out from my hoses. Especially my HP hose.

-marku

 

[Charlie99]

The pinhole in the HP port of my Atomics B1 reg is so that if a hose fails the flow rate will be reduced. Some HP hoses come with flow restricting pinholes for the same purpose, although they aren't needed with the many regs that already have a flow restricting pinhole in the HP port.

Any pinholes/orifices in the HP hose are supposed to be inline between the reg and the SPG, NOT to to outside world. You SHOULDN'T be seeing any bubbles come out of the HP hose.

This pinhole, BTW, is why an HP hose failure or SPG failure doesn't cause anywhere near as fast of a loss of tank pressure as does an LP hose failure or reg freeflow.

 

[miesemer]

Charlie99,

I think marku is asking about tiny perforations in the hose skin. They will be an indicator (tiny bubbles)of a failing inner tube.

Jeff

 

[scubatoys]

Yea, if you slice a HP hose open, you'd see that internally, it's rubber reinforced with braided metal. The metal holds the pressure, but the rubber holds the air... if you get what I mean.. So if the rubber breaks down, dry rots, etc, air will leak out thought the rubber and braided hose.

The outside layer of that hose is what you see. Now if that air that was leaking through a dry rotted hose had no place to go, the outer casing of the sleeve would balloon up then pop. Better to have a line of pin holes along the casing so if the hose is going bad, you can see tiny bubbles form on the hose. I've seen them at a pretty dramatic fizz... and still people would use them instead of buy a new HP hose.

 

[Dive-aholic]

You shouldn't be diving that hose. Replace it now. It's an early sign of impending hose failure.

 

[herman]

You shouldn't be diving that hose. Replace it now. It's an early sign of impending hose failure.

Not if what he is asking about are the small holes all over a high pressure hose. If you look closely at a new hose it has very small holes all over it's surface. Like Larry explained, a HP hose is really 2 hoses in one. The inner hose holds the pressure and the outter hose protects the inner hose. The outter cover has small holes in it to vent air in the event of an inner section fails, otherwise it could blow up like a balloon and explode. If Mark is seeing small streams of bubbles coming out of the small holes then it's past time to replace the hose, it has failed. If there are only a few bubbles, the inner hose has only failed a small amount but it's past time to replace it, major failure could be comming soon, but if all he is seeing are the small holes in the outter covering with NO bubbles, the hose is fine.

 

[John C. Ratliff]

Not if what he is asking about are the small holes all over a high pressure hose. If you look closely at a new hose it has very small holes all over it's surface. Like Larry explained, a HP hose is really 2 hoses in one. The inner hose holds the pressure and the outter hose protects the inner hose. The outter cover has small holes in it to vent air in the event of an inner section fails, otherwise it could blow up like a balloon and explode. If Mark is seeing small streams of bubbles coming out of the small holes then it's past time to replace the hose, it has failed. If there are only a few bubbles, the inner hose has only failed a small amount but it's past time to replace it, major failure could be comming soon, but if all he is seeing are the small holes in the outter covering with NO bubbles, the hose is fine.

This is pretty accurate, but realize that all hoses will leak some molecules of air. If these holes were not there, that air would accumulate under the outer layer, and eventually cause the hose to fail (a "bubble" under the outer skin of the hose). This is an engineering control for lenthening the life of the hose, because some very small amount of gas will come through. It is especially important for dives with "exotic" gas mixtures such as helium, which goes through almost any barrier. A very small amount of bubbles is of no concern; if there is a steady stream, then the hose has broken down (as described above) and should be replaced.

SeaRat

 

[brucebowker]

Water can squeeze down these tiny holes putting a small amount between the outer rubber case and the inner hose. When the regulator is turned on the pressure increases the diameter of the inner hose forcing this water out. These can look like bubbles but the hose is still fine. If a steady stream of bubbles, then the hose is bad. If it just a one time foamy type of bubble than it should be OK.

 

[marku]

Thank you very much guys!!
And yeah, I changed my HP hose already. No more bubbles.

 

[Dive-aholic]

Not if what he is asking about are the small holes all over a high pressure hose. If you look closely at a new hose it has very small holes all over it's surface. Like Larry explained, a HP hose is really 2 hoses in one. The inner hose holds the pressure and the outter hose protects the inner hose. The outter cover has small holes in it to vent air in the event of an inner section fails, otherwise it could blow up like a balloon and explode. If Mark is seeing small streams of bubbles coming out of the small holes then it's past time to replace the hose, it has failed. If there are only a few bubbles, the inner hose has only failed a small amount but it's past time to replace it, major failure could be comming soon, but if all he is seeing are the small holes in the outter covering with NO bubbles, the hose is fine.

Right, but marku did state in his post that tiny streams of bubbles do come out. That's what I was responding to.