Source
r/scuba•
ahugenerd

Drysuit exhaust valve profiles

I've been trying to figure out if there are any substantial differences between high profile and low profile drysuit exhaust valve. I understand that the lower profile ones are marginally less likely to get caught on stuff or knocked around, but are there any downsides as compared to their high profile counterparts? Basically, I just want to better understand the pros and cons. Not trying to ignite an Apeks vs SiTech debate, I swear!

Posted Jan 27, 2019, 6:21 PM UTC

812
StrawberriesOfSloth•

The nominal flow rates through the newer low profile valves are significantly higher than high profile valves, but some people insist the high profile valves are easier to vent. I don't know if it's some factor outside of flow rate, like maybe the high profile valves are just easier to trigger even though they dump more slowly, or maybe people are just imagining it. On paper, though, low profile valves should perform better across the board and I've never had any issues with them. I find the cut of the suit makes a far more noticeable difference—some drysuits I just cannot get to dump quickly no matter how I position myself—as does the valve being positioned properly on the shoulder.

3
ahugenerdOP•

So, if I'm understanding correctly, there's no real valid reason not to go with a low profile exhaust valve these days, and the debate now is more about SiTech vs Apeks or single vs double checked (I.e. Viking Hazmat).

3
StrawberriesOfSloth•

That's my assessment of the situation, yes. But I've only ever significantly used the low profile valves myself, outside of a few short term rentals with high profiles, and one of the people I know who really prefers the high profile ones is someone in the drysuit repair business who knows more about drysuits then I ever will. So it's possible there's some secret sauce I just don't get. However, for my own experience, I've been perfectly happy with low profiles and, like I said, there isn't a non-magical explanation I've been able to find for why high profile valves should perform better in any way.

1
golfzerodelta•

For Apeks specifically, per this thread it looks like the high profile valve is much slower to vent gas compared to the low profile valves (the image itself is from the Apeks Manual).

2
ahugenerdOP•

This is extremely helpful information, thanks!

1
runsongas•

The apeks valve doesn't auto dump as well imo. Also some people complain it leaks a bit when fully open. You also get more turns with the high profile and it can be a little easier to press. I think the medium profile sitech is the way to go if you need a new valve.

2
JV2016_com_Ventura•

Who has experience DIY repairing their drysuit valve ports? What nuggets of hard-earned wisdom can you share?

2
CaveDiver1858•

Just toss it. You can disassemble and clean the mushroom valve but really it’s such a cheap part and such an important part it’s not worth the headache or time.

1
kvyatkovskij•

I'm not sure it's answering your question perfectly but I had experience servicing my si-tech inflation and exhaust valves. Inflation valve was sticking open slowly inflating me during the dive and exhaust valve got a bit of leak.

Inflation valve - really straightforward except for the part where you need to unscrew a socket cap screw. It was very tight and socket is too small so I messed the socket. With help of my dremel I was able to cut a line for a flat screwdriver which let me take that screw out. Home depot had just right stainless steel screw in store which I got as a replacement. After that things were easy - nice wash, some O2 compatible lubricant and my valve is just like new.

Exhaust valve - got a nice video on how to disassemble and reassemble Si-Tech exhaust valve https://www.youtube.com/watch?v=gb4UCVIXWeA with one downside: I think assembly was done wrong at one step and I ended up with a valve that sort of works but it would hold higher pressure than needed which made my first dive after the service quite interesting. Tip here: you can test pressure levels just by blowing through the valve when you take it out. Open and closed feel quite different and if you assembled your valve wrong you'll feel it if you blow through it again.

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CaveDiver1858•

I find the si tech and low profile apeks exhaust valves to leak far sooner than the apeks high profile valves.

1
redcoat777•

Something to consider is that low profile may be hard to press with big mits on.

1
FujiKitakyusho•

https://www.divedui.com/pages/drysuit-dump-valves-an-addendum-to-the-exploration-suit-of-choice

1