Drysuit Exhaust Valve Modification

[Deep South Divers]

Anyone that's been diving drysuits for any length of time knows the awful feeling when you're in the middle of your dive and you feel that little trickle on your left shoulder. It doesn't take long for your whole left arm to get soaked, cold, and miserable.

Many of us have learned how to remove the suit's exhaust valve, disassemble, and clean it out. It seems a right of passage somehow...

As a commercial diver diving in silty, salty, muddy environments most of the time, the annoyance was a real problem... Exhaust valve leaks were a problem sometimes even the day after cleaning and rebuilding the exhaust valve if the conditions were really that bad... And if it happened on the first dive of the day, it could mean a whole day of misery or even a canceled dive and lost wages.

...So for years I tried using different brands of exhaust valves, including Apeks, SiTech, Apollo, and even some Japanese valves that you wouldn't recognize. I tried custom-fabricating my own filters and screens for my exhaust valves, and at one point I even had SiTech's engineering department working with me to create some really cool stuff.

Some were better than others... But none have solved the problem entirely - until now.

I share the modification with you in this video... You'll get a kick out of it. Enjoy. Hope this brings some people some very long, dry dives.

 

[ZeroG]

Nice video. Won't surprise me this (or similar) design shows at DEMA or my LDS. Well done.

 

[Deep South Divers]

Thanks!

Boy, that'd be nice... But SiTech didn't seem interested when I spoke to them.

 

[lexvil]

While I’ve never had a dump valve leak I do dive it fully open most of the time so maybe I’ll try this one day. The trigon has a check valve in the base too, although it’s pretty small and would probably be pretty slow to dump.

 

[Deep South Divers]

The top half of the Trigon has TWO check valves in it.

The bottom half of the cuff dump has ONE check valve in it.

Together, they make three check valves.

Don't use the bottom half of the Trigon; that part IS very restrictive. If you don't have the bottom half of a cuff dump, buy one - or use the bottom half of your regular exhaust valve and deal with having TWO check valves instead of THREE.

All three of the check valves in the Trigon and cuff dump are the exact same umbrella valve that is used as the check valve in the regular exhaust valves... So no, they're no more restrictive than any other dump valve.

That said... The holes in the Trigon top are smaller than those on the other exhaust valves... So what you say MIGHT be correct. If so, the restriction is in the cosmetic top of the Trigon, not in the valves.

For what it's worth, the top is NOT sealed to the valve body - so anything that restricts at the holes probably just leaks past the top.

Bottom line? If there's a difference in how quickly it dumps, it's neglegible. I've personally never noticed a difference.

...Except that it doesn't hang my rig when donning and doffing... It doesn't accidentally get tightened... And of course, it never leaks.

 

[lexvil]

The tip half of the Trigon has TWO check valves in it.

The bottom half of the cuff dump has ONE check valve in it.

Together, they make three check valves.

All three of them are the exact same umbrella valve that is used as the check valve in the regular exhaust valves... So no, they're no more restrictive than any other dump valve.

That said... The holes in the Trigon top are smaller than those on the other exhaust valves... So what you say MIGHT be correct. If so, the restriction is in the cosmetic top of the Trigon, not in the valves.

For what it's worth, the top is NOT sealed to the valve body - so anything that restricts at the holes probably just leaks past the top.

Bottom line? If there's a difference in how quickly it dumps, it's neglegible. I've personally never noticed a difference.

...Except that it doesn't hang my rig when donning and doffing... It doesn't accidentally get tightened... And of course, it never leaks.

I think you misunderstood, the trigon bottom the one one inside of the suit also has a check valve, the balance part of the system. It was just a thought on the use of the trigon by itself without the use of the cuff dump part. If someone wasn’t worried about the third check valve they could just run the hose to where ever the want to vent from, by the wrist to act like a wrist dump with the hose blanked off I don’t think the tiny holes on the inside of the trigon would vent fast enough. I do like the lower profile part of this.

 

[Deep South Divers]

Yes, I understood your point.

The bottom half of the Trigon has a very tiny "balancing" hole in it that would be practically useless for dumping. The metal bib where the hose connects would probably vent fine, but has sharp edges not friendly to the inside of the drysuit or during doffing or donning. Using a hose like you mentioned wouldn't work well because you'd have to still vent up through the tube. If you raised your arm like you mention, the hose would be able to enter the tube, but would not flow DOWNWARD to the exhaust valve. The only way to vent something like that design reliably would be to take "gulps" of air with the internal hose and drive them up toward the valve, making the diver "do the wave" in order to vent anything at all... And if the hose wasn't aligned perfectly with the top of the arm, it wouldn't vent anything.

If you want to forego the cuff dump, it IS possible... Simply use the bottom half of the regular exhaust valve with the top half of the Trigon - that will give you a reliable exhaust valve with TWO check valves, and still give you the low profile and nonadjustable top. Yes, they are threaded the same and the same size.

...But I recommend adding a smaller cuff dump bottom, which makes the profile even smaller and lower, and adds a third check valve.

 

[Deep South Divers]

By the way... You've NEVER had a dump valve leak? Do you rebuild between every dive? Diving only perfect, freshwater conditions? What brand/model of dump valve are you using?

 

[lexvil]

Mostly shore dives, some boat but usually if I travel to a boat site I’m diving wet.
I have not had this issue of leaking with regulat si-tech dumps on 3 different suits, I’m not getting as much debris around my valve for sure but there can be a fair amount of stuff in the water near shore. I like the idea of a lower profile and a smaller adjustable one would be nice for the few times I’m mixing it up with sea lions so I can roll each way.

I do use my suit for boyancy most of the time and it’s normally got a bit of positive pressure to keep warm here in Monterey, the pressure probably helps keep the flow going one way and not leaking.

 

[divad]

I share the modification with you in this video... You'll get a kick out of it. Enjoy. Hope this brings some people some very long, dry dives.

Nice work........tinker on, dude, tinker on........