I also went through a bout of issues with exhaust valves leaking. Despite disassembling the exhaust valves nightly and cleaning them (I have several and would swap them out), the suspended particulate matter in the contaminated waters that I was working in would quickly make exhaust check valves leak... Even during dive #1 of the day after disassembly and cleaning. I had a lot of luck with using a lady's nylon stocking under the top cover of the valve to keep the debris out to begin with, and sent the information to SiTech in hopes that they would make a better, more protected valve:
Eventually I stopped using a nylon stocking and began using a cut-to-fit piece of a 3M "scratchy" pad, which is very similar to the filter used in the suit-side filter of the SiTech exhaust valve to keep undergarment lint out of the valve. It worked well, too.
For a while I believed that I could improve on the exhaust valve design with a different type of umbrella valve that was better preloaded. Here's a video of me explaining that to a valve manufacturer, in hopes that he would create for me a valve that would snap into a SiTech valve housing:
...And me explaining to him how to get the valve apart so that he could examine it and create a new umbrella valve. This information has been heavily sought-after by anyone who's ever had a leaky SiTech exhaust valve, which is pretty much anyone with just about any brand drysuit with more than 25 dives on it:
In the long run, I found a better solution to leaking exhaust valves that is simpler, more reliable, and more easily obtained... Without having to spend $2500 in tooling costs to create a new umbrella valve. Use the top half of SiTech's new Trigon pee valve mated to the bottom half of a standard exhaust valve. Conveniently, the Trigon uses the same-sized hole as the exhaust valve and is threaded the same, so they go together like peanut butter and jelly.
The advantage to using the top half of a Trigon with the bottom half of of a standard exhaust valve is that the Trigon is much better designed, and as such doesn't leak:
1. The Trigon valve body (the top half) has a double check valve as compared to the single check valve of the standard exhaust valve. By default, the valve is twice as dry.
2. The Trigon valve seat - where the check valve makes the seal - is heartier with a better, more complete sealing surface than the standard exhaust valve. Times two.
3. The Trigon valve body is made of delrin rather than ABS plastic, which is much more rugged.
4. The Trigon has no adjustable valve system - it's simply open, which is how the majority of drysuit divers adjust their exhaust valves anyway. To many drysuit divers - me included - this is an advantage, as the adjustment is always exactly where you want it - fully open.
5. At about 3/8" tall, the Trigon valve is a fraction of the height of a standard SiTech exhaust valve, meaning it's much more streamlined and unobtrusive. Only a SiTech cuff dump is lower profile (by 1mm), and it has only a single, unprotected check valve. This super low profile valve makes donning and doffing a backplate and wing or BCD a much simpler and cleaner affair.
6. With many small holes facing directly toward a protective lip, the Trigon is much less likely to become contaminated with particulate as compared to the large, open, top-facing slots of the SiTech exhaust valve. It thus stays cleaner and is better protected from contamination, which keeps the valve functioning better and without leaks.
7. Disassembly of the Trigon valve is a simpler, easier affair than it is with the standard exhaust valve, and getting to the umbrella valves and their seats is a quicker process. Unlike the standard exhaust valve, it can even be done without tools. As such, it tends to get more attention from our divers, meaning that the valve is more often clean and therefore functions better than the standard exhaust valve.
Here'a video of me explaining this to BARE. I also cover the awesome Waterproof Ultima dryglove rings and Showa's fantastic Atlas 660 gloves, which come in three different colors, thicknesses, and liner options. There's even a kevlar version.
Yes, it's true... Dry diving. For real. Like, really dry. No lie. Not a leak, even in this:
I'm confident that someone, somewhere will criticize the use of a Trigon as an exhaust valve due to it having a lower flow rate than a standard SiTech exhaust valve. I suspect that the flow rates may be different due to the smaller holes in the Trigon, but we'd have to test the flow rates to be sure... Any difference is not immediately obvious to our divers. But what IS obvious is the lack of cold, wet arms and leaking suits.
