DUI venting from neck seal

[DavidLoPan]

Good afternoon.

Last weekend I was diving catalina taking my drysuit out for a spin. I had a couple questions (perhaps some tips and tricks) that were not covered in the drysuit class.

First i noticed that when i was making my ascent I would vent out the air through the neck seal? I made sure the exhaust value was open all the way before making the ascent from the dive. I would ascent in a horizontal (sky diving) position; making sure it was slow and controlled. Is venting from the neck seal normal? if not what are some of the tips more experienced dry suit divers can offer.

Second, when making a boat entry should i close the exhaust valve (then open it out, of course, before the dive)?

Any feedback and 2 cents is greatly appreciated.

Thanks much!

 

[knowone]

The exhaust valve is never closed, exhaust resistance is increased

Having the water pressure expulse the suit of excess surface air on entry before you attempt to descend is good

With a negative entry, keep it on maximum resistance as you will be adding air to avoid squeeze pretty quickly

You need to get a Schwarzenegger neck

and a book


If I had a neck seal that vented automatically without the ingress
that gives me the shivery jiveries I would be a happy chappy.

 

[w ripley]

I haven't dived a neoprene neck seal in while, but have been diving latex for some time. I have the DUI zip seals and find that every so many years the latex becomes relaxed and when I first enter the water, especially if jumping, air will vent thru the neck. You shouldn't be having that problem, but even tight seals will vent that way if you don't purge the suit before you put your gear on and if you jump in feet first. (Actually, I purge my drysuit, wings and counter lungs before jumping off a boat.) I realize I'm off track here.

Your suit should not be venting thru any seals on ascent. If so, then you aren't venting your suit as you come up or you're coming up way too fast. Sometimes the material of your thermals will block block the dump valve. You might want to look at that. If your thermals have a hard covering that should not be the problem.

Check your horizontal position. If you are truley horizontal, and your dump valve is working. then maybe you aren't horizontal. Or maybe you aren't geting your arm high enough for the air to find the dump valve. You can also roll over slightly in the horizontal postion so that your dump valve is the highest thing in your suit.

It may be that you simply trimmed your neck seal too much. If you aren't getting a good seal, then you suit should be wet. If your suit is dry inside when you surface (they are all damp - but not wet - after a good long dive), then it's probably not the size of your neck seal opening.

Concerning the exit, I normally add a great quantity of air to my drysuit so that I can climb and walk easier. I have also closed the valve before doing that. Whatever works. Other than that, as you mentioned, the dump valve should remain open.

 

[TSandM]

If you are venting in a horizontal position through your neck seal, then one of several things is true. Either your dump valve is not dumping (not really open? Diaphragm stuck down?), or you are carrying WAY too much gas in the suit (overweighted?), or your neck seal is too loose. Even if you are not as horizontal as you think you are, you should not normally lose gas through a properly fitted neck seal.

The first thing I would do is check the seal. When you put the suit on, a latex seal should feel just on the verge of uncomfortably tight. Your face shouldn't turn blue, but you should definitely be able to feel that you have something elastic compressing your neck. If you can slip a finger under the seal without feeling significant pressure on the finger, the seal is old or was cut too big.

If the seal seems correct, put the suit on, and then squat and squeeze your arms across your chest. You should hear a good rush of air coming out of the dry suit dump valve. If you don't, it's not working correctly. If this was a used suit, it is possible that the diaphragm in the dump valve has gotten sticky from debris or algae, and isn't opening easily. Soaking the valve overnight in clean water, and then rinsing it from the inside out, will usually fix that problem.

If the dump is working and the seal seems right, then check your weighting. If you are using the dry suit for buoyancy, as is often taught, you can't be very much overweighted before you simply can't maintain that much air in the suit.

 

[jar546]

Never had that happen. I like the theory of the overweighting issue and over-inflated suit. Maybe the neck seal is too loose. My neck seal actually sticks to my skin after a while which is a good thing.

 

[ajduplessis]

The problem is related to venting, thus 2 likely issues. a) The neck seal is to lose b) The dump valve is not functioning the way it should, this could also be related to your thermal wear blocking the valve.

 

[Steve50]

Good advise above. A key point TS&M hit on can be if controlling buoyancy with just the suit (as opposed to the BCD), the air needed in the suit can cause burping out the neck seal with the penalty of water coming in...

 

[vjanelle]

Are you purging the suit after zipping it up? If you just close it there's going to be a lot of air in there and that'll come right off if you jump into the water.