DIN connection leak after 'out of air' simulation

[Markos Valsamis]

On a practice pool dive I was practising turning the tank valve off, the buddy signalling out of air, then turning the air back on. When I turned my buddy's air back on, there was a very large leak of air from the DIN connection on the first stage. This was uncomplicated as I gave my buddy my octopus, end of story.

Question: why did the DIN connection leak? There was no problem with the o-ring as I later confirmed. It just seems that turning it off and on underwater resulted in the seal failing.

 

[tbone1004]

it probably got bumped during the drill while it was depressurized and unscrewed itself. Doesn't take much to get it to leak

 

[Markos Valsamis]

it probably got bumped during the drill while it was depressurized and unscrewed itself. Doesn't take much to get it to leak

Thanks, makes sense. I guess it is much easier to unscrew when not under pressure! Would it be reasonable to conclude that water may have got into the first stage in that instance?

 

[tbone1004]

Thanks, makes sense. I guess it is much easier to unscrew when not under pressure! Would it be reasonable to conclude that water may have got into the first stage in that instance?

yes, but if it was in a pool and you've already used it, the first stage is clean. Only thing that would be bad is if anything got into the SPG, but it's unlikely that much water got in there. When practicing OOA, I wouldn't shut the tank off and breathe it down though

 

[fmerkel]

Be aware that the DIN can leak from the tank connection (most likely), but also from the reg itself. If the other end was loosened, maybe by someone torquing the entire reg to get the DIN unscrewed from the tank (this happens), it can loosen there also. It's essentially a bolt with threads on both ends-one to the tank, one to the reg body.

 

[stretchthepenn]

This same thing happened to me on an out-of-air drill. Combined with the crappy day I was already having, the experience was thoroughly unnerving.

As said above, it sounds like the DIN post came unscrewed from its fitting into the 1st stage body. There's supposed to be a specific torque setting for re-screwing the thing into place, but in practical terms, tightening it down firmly (but not super-tightly) with an Allen wrench will fix the problem.

 

[dberry]

The same thing happened to me in Cozumel this summer. Open tank, hissing from the 1st stage. The DIN post was loose into the body, and trying to tighten it without a wrench was fruitless. It was loose enough that a small o-ring got extruded (or distorted) while still on the boat. I had a spare o-ring, and an Allen wrench to tighten it, end of story.