BDC Power Inflator

[moosicman]

During my certification we never once used our power inflator, and instead manually inflated the bcd EVERYTIME which is actually cool with me. my instructor said this was to minimize the RARE chance of the power inflator button getting stuck in the "on" position and sending you to the surface, PLUS it saved your air. so my question is...how much of a "standard" is this. is this how YOU do it or is this the exception to the norm?

[ScubaToys Larry]

I'd say the exception. First off, a stuck inflator button should not send you to the surface. All BC's dump faster than they inflate, so you should be able to just pull the pull dump and get air out faster than it's going in. And it's pretty simple to just unhook the inflator hose. And any time I've seen a sticky inflator, it's normally because it's been dragged through the sand for years and never serviced. I've yet to have one stick.

I've seen it on some other peoples stuff... and normally it's as easy as pulling on the button, or smack it once and it stops. Then open it up and get the sand out.

[mm_dm]

I also heard of a Instructor who taught his students that the constant free-flow of the regs they used in class was a "self-cleaning" feature of the reg. We spend a fair amount of time teaching students to orally inflate their BC and practice them on disconnecting the low pressure inflator hose from the inflator itself and orally inflating. But, it would seem to be over-kill to use that as an exclusive method. I trust my low pressure inflator as much as I trust my regs and other gear...and have my equipment serviced regularly to keep them in excellent working condition. Some shops are less strick about servicing their gear and the Instructors get stuck with the end result in class. You can imagine how frustrating that would be when you have a time window and a certain amount of material you want to cover, but you have to spend time doing somebody else's job for them. It does save air, but in a recreational class setting, is it really that critical?
Just my two psi.

[nathanbarlow]

anyway technically you are supposed to have no air in your BCD or wing - having to inflate it is a sign you are overweighted.... so only time you should inflate is when you are ascending or at the surface

[moosicman]

there wasn't an overwhelming emphasis to not use the power inflator, we just always orally inflated. although he did have a training emergency when a kid in his class once got it stuck in the "on" position and luckily nobody got hurt, but it was a valuable lesson and we did practice disconnecting the LP hose in that event

[wgt]

I have encountered the problem on three occasions during the years -- twice on BCDs and once on a dry suit inlet (disconnection of the hoses solved the problems instantly). All pieces were the subject of regular service (once per year). In two cases, a visible piece of debris had been trapped between the hose and the connector, suggesting the accidental introduction of the debris during storage or transport and inadequate visual inspection during assembly. The third case involved accumulated deposits from bad rinse-water, suggesting the need for a more-than-regular servicing (e.g., once per 8 months).

Recommendations:

1. Visually inspect all connections before engaging.
2. Consider the quality of customary rinsing efforts and water in relation to setting a maintenance schedule (noting that most divers in the US would not face rinse-water issues).

[Damselfish]

Originally Posted by nathanbarlow

anyway technically you are supposed to have no air in your BCD or wing - having to inflate it is a sign you are overweighted.... so only time you should inflate is when you are ascending or at the surface

well no, that depends on your exposure protection and other factors. For example if you are wearing a wetsuit and are at the beginning of your dive with a full tank, when you descend the wetsuit will compress and you will be putting air in the BC to maintain neutral bouyancy. And you will probably be deflating as you are ascending because you wetsuit is decompressing again, and your tank is gradually getting more bouyant - inflating on ascent is a recipe for shooting to the surface.

Even without a wetsuit you may want a little air in your BC at the beginning of the dive because your tank is full and you are (hpoefully) weighted for the end of the dive when the tank will be more bouyant.


Anyway, it's good to have practice orally inflating, but it's not the standard anymore to do it all the time - the standard is to have a power inflator and use it. It became standard because it was thought an improvement. It's not going to save much air, may even use more because of the way it interupts your breathing pattern.

[moosicman]

Anyway, it's good to have practice orally inflating, but it's not the standard anymore to do it all the time - the standard is to have a power inflator and use it. It became standard because it was thought an improvement. [/quote]

LOL....my instructor is an old school marine diver. i feel actually quite fortunate to have him train me because (from what i've been told by others in the chat room) he has trained me ABOVE and BEYOND what most people get.

[nathanbarlow]

Originally Posted by Damselfish

well no, that depends on your exposure protection and other factors. For example if you are wearing a wetsuit and are at the beginning of your dive with a full tank, when you descend the wetsuit will compress and you will be putting air in the BC to maintain neutral bouyancy. And you will probably be deflating as you are ascending because you wetsuit is decompressing again, and your tank is gradually getting more bouyant - inflating on ascent is a recipe for shooting to the surface.

A 10cm thick piece of pure neoprene at 60metres is around 3cm thick - so pretty much a 7mm suit at like 20m (standard recreational dive) wont change thickness enough to mess with bouyancy that much, only thermal properties. . If you're doing depths of like 60m+, you will probably be using a drysuit as a redundant bouyancy device, so is moot point then.

Even without a wetsuit you may want a little air in your BC at the beginning of the dive because your tank is full and you are (hpoefully) weighted for the end of the dive when the tank will be more bouyant.

thats only with aluminium tanks. This is why I prefer steels (as do lots of other people for the same reason)

So yes, using aluminiums you would probably have some air in your BCD/wing at the start, but otherwise no. . .

[Damselfish]

like I said it depends, pointing out a blanket statement was not necessarily always true.

a 7mm compressing absolutely can changes your bouyancy enough to make a difference. And many people using drysuits use the BC to control bouyancy not the suit.

and the bouyancy of a tank still swings whatever it is made out of. Sure, steel may end negative instead of positive like most aluminums, but the weight of the air is the weight of the air.

(and I have dove a 7mm farmer john and steel tanks.)