Blown O rings?

[fookisan]

I hear about blowing O rings, but how common is it to actually blow one? If blown, can you still get air for a few seconds or does water rush into the reg? What causes them to blow? A nick, old age, attached 1st stage too loose or tight or just a mystery?

Thanks,

Dan

 

[ScubaFreak]

Hi fookisan,

O rings blowing can be a couple of things, dirt or grit on the O-ring, non-regular servicing of the equipment (eg regs), or at one stage we got in a batch of bad O rings and all the tanks rings blew withing a few minutes of turning them on.

But don't worry, no matter where an O ring blows, it wont restrict your airflow. Yeah it will deplete your air faster than desired, but should definitly leave you with enough air to get to the surface.

Scubafreak

 

[fookisan]

Thanks for the info,

Dan T

 

[Scubaroo]

If you're talking about a blown yoke o-ring, they empty your tank in a BIG hurry (I've had one blow underwater). Water doesn't rush into the reg - air is blowing out!

From memory the tank went from something like 3000psi to 400psi in about 30 seconds. Not much time to ascend safely if any sort of depth had been involved.

 

[miketsp]

In 170 dives I've had 2 orings blow. One on the boat and one at depth.
When the one went at depth I just couldn't believe the noise level. It was like somebody revving a motorcycle right behind my head. It really made it hard to think about what was happening. Next time I'll recognise the sound for what it is much faster.

 

[Scubaroo]

DIN fixes the problem - unfortunately not all travel destinations use DIN valves.

 

[Diver0001]

I hear about blowing O rings, but how common is it to actually blow one?

I help with training at the LDS and spend a lot of time at the local training site around people using rental gear and I see blown o-rings frequently. It's common enough that if you use standard attachment for your reg that I'm 100% sure you'll eventually get one. If you're lucky (and what happens most often) it will happen when you turn the tank on.

If blown, can you still get air for a few seconds or does water rush into the reg?

It creates a freeflow but you can still breathe. The good ones create a big enough freeflow that you'll need to surface immediately. You'll live but it might scare the bejezus out of you if it happens under water.

What causes them to blow?

The pressure in the tank causes the o-ring to extrude between the 1st stage and the tank valve. It happens most often, I think by the o-ring not being maintained. They just wear out and if you don't replace them they'll eventually start to leak. A loosely fitting 1st stage or any kind of damage to the o-ring or the tank valve won't help either.

When I was still using a standard clamp on the reg I used to carefully remove the o-ring and flip it over after 5 dives and replace them after 10 even if I wasn't seeing problems. Doing that I avoided getting a blow-out for several hundred dives. I think if you rent tanks that you sould be prepared to replace the o-ring before you go diving.

And if you're seriously considering getting your own gear then you can avoid the whole issue by going with DIN fittings instead. Retro fitting a regulator and tank with a DIN fitting costs about $50 give or take. At least around here.

R..

 

[hecker-the-wrecker]

I was leaving our lds with my new al100. I asked if they had filled it up. The saleswoman grabbed the "tank checker" and it immediatly blew the o-ring when she engaged the air. She re-adjusted the o-ring, "pow!!!" When I joked around and said I might not want the tank, she replaced the o-ring, re-filled the tank, and gave me a half dozen o-rings to take with me.I have 20 dives and no problems.I think it was a defective o-ring.

 

[Al Mialkovsky]

Our shop was using these little white O rings and they seemed great. More expensive that the regular ones but they just worked great. Until during a class I had two O rings blow in the pool. They all seemed to get very soft and I've replaced every O ring in the shop now. Sometimes more expensive isn't better.

 

[hecker-the-wrecker]

The o-ring that blew on my new tank was white, that was the one that came with the tank. It went in the garbage and a new black one took it's place. Interesting!!!