Safety valve: left vs. right, top vs. bottom.

I'm about to purchase my first bcd. I'm looking for a simple, lightweight wing for single tank such as apeks wtx30, tecline donut 17, etc. Every one I see seems to have the safety valve located on the left side, and bottom (i.e. closer to diver's back) rather then top. All recreational bcd I've seen have them on the right, and closer to the surface.

Why the difference? Is there something with the valve on the right, so I don't have to change my habits?

Also, I guess that the upper valve on the diver's arm will always be missing on 'technical' equipment?

Thanks!

I can't speak to the "why" of many wings not having the valve on the upper/right shoulder, except for maybe that they figure the fewer the better since they can fail, and there is already one on top with the inflator hose.

I find that I like way they are (one on lower left; one at inflator on upper left shoulder), because then my left hand is the buoyancy hand either way. If I'm vertical I can use the inflator, but most of the time when I'm diving I can just use the bottom valve and I don't have to change position much or hold a hose up.

The fact that the lower dump is on the "underside" of the wing doesn't seem to play out that way in actual use. I guess because of the way the wing folds/positions/pontoons when you are diving that valve seems to be in the right place; I think if it were on the top (i.e. the side away from your back) that it would actually not work as well.

The thing is, I got used to always keeping the inflator hose in my left hand when diving, but using the safety valve for releasing air. Not a best practice maybe, but saves me searching for it, and doesn't have any downside I can think of - I hardly use hands when diving except for a torch maybe, and it goes in my right hand anyway.

Here is a few reason why they are the way they are.

Dump value on left side only because tech diver's left hand is for buoyance control. Depth gauge is mounted on right wrist, so that they can monitor depth (especially on ascent) while dumping air.

Dump value on he inside has a few reasons: 1)less likely to be damage. 2)if diver is properly weighted, the wing will be almost empty all the time. The wing will taco. If dump valve on the top side, diver won't be able to find the value. 3)if valve fail, wing can still hold some air if valve is mount inside. Top side failed valve will vent all air.

No dump value in corrogated hose because if you pull enough, (they are hold by zip tight) this thing will come out and you can't inflat you wing anymore.

All of these are not likely matter to recreational divers. But keep in mind is that these equipment were designed with tech diving in mind. If you are properly weighted, you should be able to do a lot of buoyance controrl just by using your lung. Only when you do a major ascent/descent, you will need to mess with the inflator/dump valve.

Thanks,
I suspected I was doing something differently; I always wore my diving computer on my left hand just like a watch and never had problems with eying it even when ascending. If tech divers wear it on the right does it mean they use torch in their left?

It seems I have to either unlearn much of my diving habits or buy a recreational travel jacket.

Yes, canister light on left hand, at least by the DIR standard.