Pull Dumps — lose them

[CuzzA]

The inflator dump valve will dump air faster than the inflator will fill the BC.. So, If you have a stuck inflator, Simply pulling down on the hose will stop your runaway accent... The low pressure hose would/should stop the BC hose from pulling off.. But then you should be taking better care of your kit if the zip ties a dry rotted...

Jim..

Really good point. I never considered it for that.

I see Jim W's point too.

 

[Dan]

I agree with @Capt Jim Wyatt . This pull dump thing is a dumb design. OEMs need to get rid of them. I see so many flaws with the design:

1. Pulling rubber hose strapped on plastic parts is never be a good thing. Something will give.

2. The pull dump functionality is not obvious. You need to pull the hose to vent the air off the vent located on your BCD shoulder, where you can’t see.

3. People have different reaction to stress. Some people might be pressing the power inflator button in a tense situation, could also inadvertently pulling the hose (especially tall people with short power inflator hose as pointed out by @CuzzA ). The pull dump could be sensitive enough to act on a slight pull and you can’t see that you are venting the air while trying to inflate.

4. Putting / combining too many devices in one piece of equipment can lead to mistakes. Human makes mistakes. I believe in KISS principle & foolproof device.

5. We need feedback on the action we do to assure us that we are doing the right thing. If I were to push power inflator, I should feel that the BCD bladder pressing on my back and I’d be ascending. If I were to push deflator button (remember I never use the pull dump for the reason mentioned above), I should be able to look up at the tip of the power inflator hose that air were venting out and my BCD bladder were deflating (relieving pressure off my back) and I were descending (by looking also on my dive computer if I were in the blue water). If the feedback were not according to what I believe it should, then something else were wrong with the device. In the case of failure to ascend, then dumping off the dive weights would be the first action to do.

 

[Umuntu]

Fair enough, and I'll state for the record that I wouldn't bring a pull dump into a cave either. The physical structure of it makes it quite a bit more of an entanglement hazard than an elbow.

Some designs present an entanglement hazard. Others are low profile and streamlined.

E.g., both the Aqualung and Scubapro pull dumps do not protrude any more than a simple elbow. The Aqualung design is actually smaller and more low profile than a simple elbow. Neither use the diaphragm design.

 

[JohnN]

I agree with @Capt Jim Wyatt . This pull dump thing is a dumb design. OEMs need to get rid of them. I see so many flaws with the design:

1. Pulling rubber hose strapped on plastic parts is never be a good thing. Something will give.

2. The pull dump functionality is not obvious. You need to pull the hose to vent the air off the vent located on your BCD shoulder, where you can’t see.

3. People have different reaction to stress. Some people might be pressing the power inflator button in a tense situation, could also inadvertently pulling the hose (especially tall people with short power inflator hose as pointed out by @CuzzA ). The pull dump could be sensitive enough to act on a slight pull and you can’t see that you are venting the air while trying to inflate.

4. Putting / combining too many devices in one piece of equipment can lead to mistakes. Human makes mistakes. I believe in KISS principle & foolproof device.

5. We need feedback on the action we do to assure us that we are doing the right thing. If I push power inflator I should feel that the BCD bladder pressing on my back and I’ll be ascending. If I pushed deflator button (remember I never use the pull dump for the reason mentioned above), I should be able to look up at the tip of the power inflator hose that air were venting out and my BCD bladder were deflating (relieving pressure off my back) and I were descending (by looking also on my dive computer if I were in the blue water). If the feedback were not according to what I believe it should, then something else were wrong with the device. In the case of failure to ascend, then dumping off the dive weights would be the first action to do.

So you think we should eliminate butt dumps too?

 

[boulderjohn]

Are these type of pull dumps common on jacket BCs and not on wings? I have to admit I don’t think I even knew they existed!

It depends. I have owned wings made by HOG, Apex, Hollis, and DRIS--none of them had pull dumps.

 

[Dan]

So you think we should eliminate butt dumps too?

Heck no. I use it when I go negative entry. It is a separate simple device. I have a ball on string on my right shoulder strap to pull & vent off the butt dump vent.

It is dang obvious what that ball on string is for. No need to read the manual. I just trace the line that leads to the butt dump.

 

[CuzzA]

Taking a step back here looking @oldschoolto's point, what is a more common failure, stuck inflator or inadvertent shoulder dumping?

My money is on the stuck inflator, which has likely actually killed divers. It seems a shoulder dump is an excellent solution for a relatively common scuba problem.

 

[Dan]

Taking a step back here looking @oldschoolto's point, what is a more common failure, stuck inflator or inadvertent shoulder dumping?

My money is on the stuck inflator, which has likely actually killed divers. It seems a shoulder dump is an excellent solution for a relatively common scuba problem.

Good point. May be we need to use it for emergency, not for regular buoyancy control.

 

[Capt Jim Wyatt]

So you think we should eliminate butt dumps too?

No, but I get your point.

 

[CuzzA]

Good point. May be we need to use it for emergency, not for regular buoyancy control.

I've never used mine except once to confirm how it fuctioned, it came with the Dive Rite HunterPac and I didn't change it. My only thoughts were I knew it was there so don't pull on it unless you want to dump gas and perhaps in an air sharing situation with the air2 it would provide an easier way to dump on the ascent.