Dry suit exhaust valve problem

fisherdvm · Mar 24, 2007

I asked the question before, while I tested it on dry land. Had my pool session today, and sure enough, the exhaust valve did not open under water at 14 ft either.

I took it apart, and it was still the same: Just one strong spring to support the manual exhaust button, and a very weak flimsy spring with an adjustable plastic plunger to vary the pressure.

Why isn't this thing working? I completed the sessions just fine, with using my manual exhaust and my wrist seal.... But it doesn't seem like I can fix it.

They have on ebay, viking exhaust valve for $15 bucks. Apparenlty they are Army surplus.... They do look like the automatic exhaust on viking suits

Should I just buy one of these and install it in place of my valve... And forget about messing with it. Should the cut hole pretty much be the same size?? Of course, I could just use it as a manual valve suit.

TimAZ · Mar 24, 2007

I'd just send it in for service. I could probably fix it myself, but if I screwed up my very expensive suit, I'd be mighty upset. At least paying to have it done another person has an obligation to make it right.

Meng_Tze · Mar 24, 2007

Not questioning anything, but are you sure it is not venting, that the problem lies with the valve? I had some issues venting in the past and discovered that it was my under garment basically plugging up the valve. A thick under suit or bungled up under the valve will stop the valve from properly venting.

One way to try to eliminate this: put on the suit with just a T-shirt underneath, close valve. Inflate suit to max and then open valve. It should vent easily. If not, then you do have a valve problem. If it does, you may want to look into the way your suit sits under the valve, or maybe your under garment is just too thick...?

Cheekymonkey · Mar 24, 2007

Alot of the automatic ones still have a manual dump on them but you have to press much harder.

fisherdvm · Mar 24, 2007

The drysuit instructor tried to monkey with it under the water, it did not vent at 14 ft.

But I am used to using it as a manual vent now.

muddiver · Mar 25, 2007

I've never had any problem with my Viking (SI Tech) exhaust valve. It is also designed not to plug when you wear thick underwear.

String · Mar 25, 2007

On a lot of suits the shoulder dump is placed in a non optimal place meaning you need to roll/salute to get it to the point where it'll dump.
Also if the suit is a little big air pockets form away from a badly placed dump and it wont dump properly.
Presumably you tried rolling so the vent is the highest point (about 45 degrees that shoulder up and slightly head up) ?

I fitted a cuff dump in my suit. Far nicer

rcontrera · Mar 25, 2007

You didn't mention what brand exhaust valve you have but most operate basically the same way. There are usually two exhaust diaphragms in the valve. One is the manual and one is the automatic. The automatic is held shut by an adjustable spring pressure while the manual one is always shut unless it is moved away from the backing plate by pressing the valve.

A common mistake that new drysuit divers make is to assume that just because they feel buoyant, that air should come streaming out of the valve. The undergarment holds an amazing amount of air. Only the excess, the air that the undergarment can't hold, is going to collect in the high spots of the diver's suit. In most cases, a roll is needed to place the valve at the top position. If the spring tension is adjusted too stiff, then it will take a BIG bubble to push the exhaust valve open. I leave mine all the way open so ANY excess air can escape easily.

If your valve is adjusted to where the spring is putting the lightest pressure on the exhaust diaphragm and it still will not allow the bubble of air to escape, then I would suspect that the diaphragm is glued down to the sealing surface by salt, silt or rubber deterioration. Try running warm water from the inside through the valve to flush whatever is on the sealing surface. You should be able to easily blow through from the back of the valve. If you can blow through the valve without pushing the purge button, then the valve is just fine.

fisherdvm · Mar 25, 2007

rcontrera:
You didn't mention what brand exhaust valve you have but most operate basically the same way. There are usually two exhaust diaphragms in the valve. One is the manual and one is the automatic. The automatic is held shut by an adjustable spring pressure while the manual one is always shut unless it is moved away from the backing plate by pressing the valve.

A common mistake that new drysuit divers make is to assume that just because they feel buoyant, that air should come streaming out of the valve. The undergarment holds an amazing amount of air. Only the excess, the air that the undergarment can't hold, is going to collect in the high spots of the diver's suit. In most cases, a roll is needed to place the valve at the top position. If the spring tension is adjusted too stiff, then it will take a BIG bubble to push the exhaust valve open. I leave mine all the way open so ANY excess air can escape easily.

If your valve is adjusted to where the spring is putting the lightest pressure on the exhaust diaphragm and it still will not allow the bubble of air to escape, then I would suspect that the diaphragm is glued down to the sealing surface by salt, silt or rubber deterioration. Try running warm water from the inside through the valve to flush whatever is on the sealing surface. You should be able to easily blow through from the back of the valve. If you can blow through the valve without pushing the purge button, then the valve is just fine.

You might have a point there, Ray, I am going to try blowing out with water. I can see where the manual flapper is working fine. But it very much could be that the diaphram for the auto valve is stuck. I just don't have the gut to try to pull it apart, thinking it was intended to be one piece.

Can't do it till tomorrow until the wrist seal is cured. I should have replaced it the same time I did the neck seal, and it fell apart yesterday after my pool session.

fisherdvm · Mar 31, 2007

Yeh, yeh, yeh.... Got it fixed. Played with it for a long time, then I figure, the spring is too strong. So I cut about 2/3 inch off from it. Dove with it, and it still didn't work.

Then I cut another 1/2 inch off it. Still didn't work. But I did it on dry land. Then another 1/4 inch off, still didn't work. Then I just took a plier, and bent the spring back against its curvature (but preserving the original round shape and diameter). I kept doing it until the whole spring is shortened by 1/8 inch. Put it back on the valve, and inflated my drysuit. (I did the disassemble and assemble while I had the drysuit on). Finally - it deflated.

I still had some air in the suit, not completely empty, but I think that I am not so buoyant that it would be a super problem at depth.

Well, now we know how to decrease the tension on these auto exhaust valve. I could have also heated the spring, but this might denatured it too much.

Thanks for all the great advises.

Dry suit exhaust valve problem

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