View Full Version : To Pull Dump or Not To Pull Dump, what a question?

12-28-2007, 10:35 PM
OK, I just bought a new wing for myself for the holidays. This is the third wing I have purchased, and I think I finally have exactly what I want. The only thing I am not sure about is the pull dump feature or lack of one.

On the first set of wings I bought, Dive Rite Dual Super Wings, both hoses had pull dumps. The second wing I bought were Dive Rite Classic wings, they did not have a pull dump, rather a standard elbow. My newest set of wings are a set of OMS non bungie wings, they also have the standard elbow. Now all of these have an inflator/deflator and all have a backup pull dump down low.

My question is what is the reason NOT to have a pull dump on your inflator hose? The other question is can I change this over without replacing the bladder?

I know there must be a reason they offer these both ways, and cost is most likely not the factor as these are not expensive parts.

The Publisher
12-28-2007, 10:56 PM
The pull dump is in the T at the entrance point to the bladder. There is a diaphragm in the T facing upwards. By pulling on the stainless steel wire, you are opening the diaphragm.

For some it is just more convenient to pull a few inches downwards and have the air escape at the highest point rather than having to raise the inflator mouthpeice exit up.

As to downsides, it is another diaphragm to fail, but if it fails catastrophically, you would have to realize exactly what is happening and rotate around so the exit t is not the high point.

I haven't heard of a failure in that mode yet, but I am sure it has happened.

Tom R
12-29-2007, 01:51 PM
It's not really needed and brings nothing to the dive, as you get better in the water and are weighted correctly you will notice that the slightest changes in air in your bcd/drysuit will effect your buoyancy. So adding or purging a little air will go a long way. The pull dump purges lots of air at once and can make you lose buoyancy and make a mess out of your trim.

Not a real fan of OMS stuff as it is poorly made most of the time and they have had a habit or at least in the local area allowed seconds to be sold off as new. The new OMS wing which I think you may have gotten is simular to the Halcyon, Oxycheck and Airq ones that are so popular amongst the cave and technical community and is starting to look like a nice piece of kit.

You can change it if you really need to try the dumps off your old wings they may fit.

A little practice with your new wing and getting your weighting down will put a huge smile on your dial. Enjoy your wing and get in the water.

This advice is free and normally people pay me for it :p

12-29-2007, 03:44 PM

You have the correct wing, it is very similar to the others you mentioned.

I was looking at the wing and it looks to be very well made. The material is very nice and the stiching and seams are tight and clean. Hopefully I still feel that way a year from now.

As far as using the new gear, the New Years dive is only a few days away. After that we are off to Florida again for some more wreck diving. I am sure the new wing will bring a smile to my face, but so will the diving in general.

Thanks for the advise, I owe you my 2 cents.

12-29-2007, 10:50 PM
The lack of an inflator "pull dump" is a recognition by the manufacturers that a properly positioned diver in the water will be horizontal in the water column.(imagine laying on your stomach) So if the diver, vertical in the water column (imagine standing up) were to try and vent air from their wing, very little gas would be dumped. This is why the dump valve in the lower corner of the bladder is the more important feature. The diver, horizontal in the water, will have the gas in the wing at that section of the wing. This attitude will provide for a much more efficient diver in the water.

12-30-2007, 06:54 AM
I've only ever owned one BCD (a Seaquest Diva LX for women) since diving day-one (check-out seven years ago) up to the present -- and so this thread made me realize I've been so conditioned to knowing I have a rear-pull dump (when I'm horizontal) AND a right-side pull dump (when vertical) for all my deflating needs (I only use the button on the mouthpiece to inflate, hardly to deflate). And I've never had a problem with purging vs. bouyancy (not surprising if it's the configuration I've been accustomed to since certification).