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Friday, February 4, 2011

Drysuit Diatribe: Valves

While I think the exhaust valve is the most interesting valve to talk about, I'm also going to talk a bit about p-valves and inflators in this post. Learning to manage the gas in a drysuit is pretty much *the skill* for learning to dive dry; it's also a skill that causes Fundies students a lot of trouble. There is definitely a big skill component to this, but there is also an equipment component. There are two problems I've seen a lot with exhaust valves. First, the valve isn't always placed correctly. In order to vent gas, the valve needs to be facing "up". If the valve is in your armpit, then no amount of contortions are going to get that valve facing up ("in your armpit" is a bit of an exaggeration, but I've seen some pretty strangely placed valves!). Sometimes the valve is placed a bit too far back, so you have to roll your arm down to get it to point up, etc. The easiest way to figure out if your valve is actually pointing up is to get a dive buddy who actually knows what they are doing to take a look at it, or better yet, to see it on video. Often times you can work around a poorly placed valve by moving your arm/shoulder in a certain way. In really bad cases, you might just need to move it, which can be done, but is sort of annoying to have to do. Again, if you get your suit from a good dealer, you shouldn't encounter this problem in the first place. I'm not saying DUI won't ever put the valve in a goofy place, but a good dealer will make them get it right for you. I like my valve to be on the midline of the sleeve.

The second problem people encounter with exhaust valves is that some valves don't vent as easily as others. In my experience, the Apeks low-profile valves sometimes have a really high "cracking pressure". That is, you have to get a big bubble of gas under it before it will vent anything, and when it finally does vent, a ton of gas comes out. I've seen this behavior over and over again in fundies video reviews (including in my own fundies class). Personally, I prefer to be able to vent a trickle at a time. I've moved all of my suits over to SiTech valves, and I love them. I believe that the Apeks high profile valves are supposed to work well in this respect too, but I just don't have the experience with them. Also, I've noticed that not every low-profile valve has this behavior -- some of them seem to vent a little at a time. So if you already have one, and it works, don't worry about it. Or if you buy a used suit that has one, wait and see if it's a problem. But if you are picking out a new suit, I'd steer clear of those valves. If you are having this problem, it's pretty easy to see in a video - you'll see a big bubble of gas right under your valve, but no gas coming out. There are certainly techniques to deal with this, but I prefer to avoid the problem in the first place. Replacing the valve is a pretty simple and low cost alteration -- Frank has done this while I waited on a number of occasions.

As far as I can tell, the main difference between inflators is that there are fixed ones or ones that swivel. I don't know if the fixed ones are even an option anymore (on DUI suits anyway), but it's something you might see if you buy a used suit. I am sure there are some additional "failure points" in the swivel inflators; I think I once had a swivel inflator that was leaking at the swivel o-ring. But this hasn't really dissuaded me from the swivel. My only advice on this is that if you are getting a fixed inflator, make sure that the inlet is pointing in the right direction. This might sound obvious, but one used suit I bought had an inflator pointing in the wrong direction. Doh! That can easily be fixed, though.

I have p-valves on both of my suits, since I've been experimenting with the She-P for ages. I'm still not really a fan, but a lot of women are. It seems to be something you either love or hate (I suspect this has to do with the one-size-fits-all aspect -- if it fits you love it; if it doesn't you hate it). Anyhoo, I don't really know much about the different p-valve options. Both of mine are Halcyon balanced p-valves. I asked Rob to write a blurb about the different options here, and this is what he had to say:

"Overboard discharge valves (P-valves) are an essential accessory for men's drysuits (and are becoming a popular addition to women's suits as well). The addition of the P-valve allows you to
hydrate as much as you want, without worrying about creating an "uncomfortable" situation in the water.

A P-valve has a valve which is mounted through the leg of the drysuit and connects via a rubber hose to an external catheter (men) or the female equivalent. There are primarily 2 types of P-valves, balanced and unbalanced. An unbalanced valve is more or less a direct connection to the outside of the suit, via a closable opening (such as pee-thru-bolt that can be opened and closed). As such, the bolt needs to be opened and closed as the diver wants to pee, so as to avoid the ocean water entering the tube. There is also arguably a slightly elevated risk of a urinary tract infection with unbalanced valves, due to the possibility of water moving in the "opposite" direction.

While unbalanced valves are simpler in design and construction, most divers these days opt for a balanced design. The balanced p-valve has a check-valve on the end (preventing water from flowing in). Also, there is a one-way valve that allows gas in the drysuit to balance the pressure in the tube, so as to prevent an uncomfortable squeeze.

The tube to the P-valve attachs to an external catheter (for men). There are several catheter brands, but the Rochester widebands are a popular choice for their "holding power". P-valves should be rinsed from time to time with a vinegar or light bleach solution to prevent bacteria growth that could lead to a UTI."

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