Question re: Wrist Cuff Exhaust Valve on Drysuit

[WKenny]

I have a DUI TSL 350 drysuit with a standard left shoulder exhaust valve that vents air very, very slowly on an ascent, and the valve is fully opened. I use a BARE "Hi Loft" undergarment. This is a Thinsulate garment with a nylon shell. Although BARE calls it "Hi Loft", it really does not seem very bulky to me. I put only enough air in the drysuit to eliminate excessive suit "squeeze" and I use a wing on a backplate for buoyancy control.

On ascents, I find that I need to continually raise my left arm to fill the sleeve with air and then lower the arm to get the air to vent from the shoulder exhaust valve. It's almost like a pumping action with my left arm. I've tried various manuvers to assure the shoulder vent is at the highest point, like rolling to my right, and raising my left elbow. The shoulder valve seems to work OK because when I put the drysuit on above water, with just a T-shirt under it, and inflate the suit with air, the air flows out of the shoulder valve easily. This leads me to think, that during a dive, the undergarment is restricting the air from venting out the shoulder exhaust valve. However, I have no trouble filling the left sleeve with air when I raise my left arm.

I understand that a drysuit does not vent air as quickly as a BC, but this drysuit vents the air soooo slowly that it seems to me to be a problem, bordering on a safety issue.

I'm considering having a second exhaust valve installed near the left wrist, or slightly higher near the forearm. I'm asking experienced drysuit divers to share their opinions with me regarding this alternative. What are the pro's and con's of having a second exhaust valve installed near the left wrist/forearm? Apparantly, DUI offers a smaller sized valve, about the size of a quarter, but it is always open and cannot be adjusted. DUI also has a standard sized valve like the shoulder valve which is adjustable.

Thank you.

 

[RJP]

I have the same suit and wear the same undergarment and have no problem whatsoever.

Sounds like a technique problem. There's something about the way you are "just raising your elbow" that is restricting the flow of air from entering the sleeve at all. Maybe somehow rotating/twisting the sleeve? Whatever it is, it is not happening when you raise your entire arm.

Have you tried extending your arm straight out and then "dropping" your forearm instead of raising just your elbow??

 

[TSandM]

I had a dry suit with a misplaced valve (it was on the front of my chest, and therefore could only vent if I were vertical and leaning backwards, which wasn't very useful). I put a cuff dump on the suit, and I did learn to use it. They vent slowly, and you really have to anticipate the need. In addition, they vent any time you raise your arm, and I was kind of surprised to find out when I did that.

I asked a lot of questions about the cuff dump before I put it in, and the one criticism people had that I didn't encounter (but I didn't use it for long) was that you can get sand or grit in them and they'll leak.

Before you put the cuff dump in, though, you might try something the USIA rep told me to do with a stucky dump valve -- Soak it in distilled water overnight, then for a while longer in distilled water with a couple of drops of liquid Ivory soap. I've done this several times now, and it works really well.

 

[String]

I use a cuff dump on my current drysuit and far prefer it to the auto (shoulder) dumps. I raise my arm, it dumps. Every time. No adjustment, rolling, odd salutes or squeezing needed.

 

[*Floater*]

My cuff dump is adjustable. When fully open and arm raised it dumps fast. It's sort of huge for the forearm though (regular shoulder dump size). Just something to consider if you decide to go the cuff dump route.

 

[dave4868]

I have a DUI TSL 350 drysuit with a standard left shoulder exhaust valve that vents air very, very slowly on an ascent, and the valve is fully opened. I use a BARE "Hi Loft" undergarment. This is a Thinsulate garment with a nylon shell. Although BARE calls it "Hi Loft", it really does not seem very bulky to me. I put only enough air in the drysuit to eliminate excessive suit "squeeze" and I use a wing on a backplate for buoyancy control.

On ascents, I find that I need to continually raise my left arm to fill the sleeve with air and then lower the arm to get the air to vent from the shoulder exhaust valve. It's almost like a pumping action with my left arm. I've tried various manuvers to assure the shoulder vent is at the highest point, like rolling to my right, and raising my left elbow. The shoulder valve seems to work OK because when I put the drysuit on above water, with just a T-shirt under it, and inflate the suit with air, the air flows out of the shoulder valve easily. This leads me to think, that during a dive, the undergarment is restricting the air from venting out the shoulder exhaust valve. However, I have no trouble filling the left sleeve with air when I raise my left arm.

I understand that a drysuit does not vent air as quickly as a BC, but this drysuit vents the air soooo slowly that it seems to me to be a problem, bordering on a safety issue.

I've used a TLS350 and then a CLx450 for over a decade with only occasional slowing of the venting process when I wear nylon-shelled insulation (Weezle Extreme Plus).

Also, just for background, my drysuits are fairly snug with my winter level of insulation. Other factors: I use a jacket-style bcd, not a backplate/wing, I use extra weight and have extra air in the suit and use only the suit for buoyancy control.

Those aren't recommendations, just background.

The times when the venting was slowed were when my shoulder straps were too tight or my weight belt was too tight or when my weighting was too close to the minimum or when I wore extra insulation and made the armpit a snug fit.

From your description of the positional nature of easy filling of the arm and slow venting, a few potential causes of your problem might be:

1. the nylon shell breathes poorly and is loose and supple, so it is occluding the outlet exhaust valve
2. the suit is a snug fit with that insulation, so the expanding air has to pass through the material to work its way to the exhaust valve, and/or the armpit/shoulder/bicep area in particular is a snug fit or your straps are too tight
3. you may be using close to the minimum weight, which would mean at the end of the dive that the suit needs to be squeezed to get enough air out to get neutral

You might experiment by doing the following:

1. prevent occlusion of the outlet of the exhaust valve by placing a few layers of fleece or wool between it and the nylon shell (place a sock under it)
2. create a channel in the shoulder/armpit/bicep area by loosening your straps a little and/or laying a piece of a lightweight piece of scarf or fleece to form a channel from the chest to the base of the exhaust valve
3. add a few pounds of lead and go with less squeeze in the suit (more air in the suit)

If you do each step separately, it will be more diagnostic, but all three will probably help. Let us know.

By the way, does the slow venting of the drysuit on ascent only occur near the end of the dive with your wing nearly completely deflated?

Dave C

 

[String]

My cuff dump is adjustable. When fully open and arm raised it dumps fast. It's sort of huge for the forearm though (regular shoulder dump size). Just something to consider if you decide to go the cuff dump route.

Ive never seen an adjustable cuff dump. Cant see the point.

A standard cuff dump has nothing adjustable, is just a diaphragm. Raise arm to dump air, lower arm to stop dumping. Far smaller than shoulder dumps.

Apeks Cuff dump in Accessories,For Dry Suits from Simply Scuba

is what i use.

Cant see the need for an adjustable cuff dump - if you need adjustable go for shoulder!

 

[Peter_C]

Ive never seen an adjustable cuff dump. Cant see the point.

A standard cuff dump has nothing adjustable, is just a diaphragm. Raise arm to dump air, lower arm to stop dumping. Far smaller than shoulder dumps.

Apeks Cuff dump in Accessories,For Dry Suits from Simply Scuba

is what i use.

Cant see the need for an adjustable cuff dump - if you need adjustable go for shoulder!

I on the other hand, can not see NOT using an adjustable cuff dump. I use a low profile Si-Tech that works very well for me. Without the ability to close it off, there are times my suit would deflate when I do not want it to. For instance when donning/doffing my gear in the water when kayak or small boat diving. Loss of suit inflation with an 18lb weight belt on would not be considered a good thing. Also when shooting pictures in different positions, I will sometimes close it off.

To the original poster, the dump location you have is the most common and does work. As said above you will need to learn the technique that allows you to vent air easily. Which valve does your suit have? Is there some type of "grate" to keep the Bare Hi loft from plugging the vent?

These are the valves I currently use and am happy with them, and the seller. If you look at the exhaust valve you can see how it has a "grate" type deal to keep the undies from plugging it.
Si-Tech Valves

 

[603doug]

Had a typhoon dry suit that only had cuff dumps on both arms, I patched the right side because I am right handed and if I reached over my head it would dump after that fix was very comfortable with it. Have a viking now and was so use to the cuff dump installed one on the left. I never have had a problem, no leaks etc

 

[jepuskar]

I'm thinking if you move to a jacket style BC instead of a BP/W you wont have an issue anymore.

good luck