ScubaPro Tek BCD won't deflate on command

[Andre Solat]

Hi,
I just bought a second-hand BCD ScubaPro TEK from a dive shop, that did a servicing, and everything feels great but...

it won't deflate whenever I wish.

let's say I feel I have too much air in it, so I try to release some from the bcd deflator button on the hose connected to the air tank, or from the dump valve. nothing happens... until I ascend more, and then the air comes out.

so it's like the bcd will release the air only when the bladder has a certain level of air pressure in it.

it this normal ? this never happens on any other bcd I had.
if it's a malfunction, could I adjust it myself ?

Thanks for any tips.

 

[beaverdivers]

Are you certain that dump valve is the highest point when you are trying to deflate it?

 

[buddhasummer]

What Beaver says.

 

[Andre Solat]

Thanks for your quick reply

Yes, the dump valve and/or inflation hose are the highest point of the bcd at the time of air release attempt.

what actually happens is that I keep pulling on either of them while ascending, and at a certain point the air gets released. So that's why I'm thinking that it might be related to the amount of air pressure in the wing. maybe the mecanism of the valves are not sensible enough ?

 

[nimoh]

are you sure it isn't empty?

It is virtually impossible to completely void your BC of gas and so when you ascend the little bit of gas left in your BC expands (boyle's law) and then can be released.

If this is the case, you are probably not wearing enough weight as most divers need to keep a little gas in their BC at depth.

 

[Andre Solat]

Thanks Nimoh,
you might be into something... It's true that I've tried to wear the least weight as possible, which worked perfectly fine with other bcd that were of the "jacket" style. and I've used the same amount of weight with the ScubaPro Tek, which has a decent size wing.
So, yes it could very be that the wing is empty, or at least doesn't have enough air in it to create pressure to release.
I will definitely add more weight next time to try that theory.
Thanks a lot

 

[ams511]

What is the lift of the wing? If it is too large or a doubles wing then you may be trapping gas.