An exhausting problem....

[pjhansman]

Current gear includes ScubaPro Mk17/G250V and an Air2, all about 1 year old. Although not a big problem I've recently experienced an issue that confuses me a bit. After a full head down feet up inversion, when I exhale, the air actually starts to exhaust out the mouthpiece of my Air2/inflator.....

This happened several times at about 40fsw, and it seems that if I purge my secondary a few times the problem goes away.

Can anyone tell me if this is this in any way "normal"......or the sign of a potentially bigger problem?

 

[redacted]

My first guess would be that the IP on your Mk17 is a bit high and/or your Air2 is tuned a bit on the hot side. An IP check of the 1st stage and a little tuning on your Air2 is probably in order.

 

[The Chairman]

I would also guess an IP creep or some other need for service.

 

[pjhansman]

Thanks for the comments.....

Fortunately (or unfortunately) the due date for my annual SP service approaches, so I'll mention it to the service guy.

 

[tfsails]

It could also mean that a bubble was trapped in the Air 2 and when you turned it diaphragm-down there was enough water pressure to collapse the diaphragm and actuate the demand lever, causing air flow. That's exactly as it's supposed to work. Next time you dive it, make absolutely sure it's full of water and not free-flowing before you go inverted. I'd bet it won't free flow.

Creeping IP probably isn't a problem, because it would cause the Air 2 to free-flow regardless of your position in the water column. The Air 2 could be adjusted a tad "hot", meaning it breathes a bit too easily and is therefore more sensitive to water pressure when not in your mouth. It shouldn't necessarily breathe like a slug, but it shouldn't breathe as easily as your primary second stage.