Pee Valve physics 101

[jimmyz19]

I am sure this has been discussed at length some place but for the life of me I cannot find what I am looking for.
I have an unbalanced pee valve on my dry suit that I have not used yet, still working up the nerve and trying to convince myself that I know what I am doing.
I don’t really know how this unbalanced valve works, other than connecting to external catheter and opening the bolt.
I have seen where some dive without the bolt and am wondering how is it that they do not have sea water flushed into the body when not peeing.
One thing that’s scaring me from using my pee valve is getting a UTI.
Is an option to just use the pee valve when on the beach before getting into the water and then using after the dive, thus keeping the bolt closed during the dive?
How deep can you be to use your pee valve, should an unbalanced have at least a check valve in line to prevent back flow?
Guess I just don’t understand the physics behind it, can anyone please help me understand this thing.
Should I just convert my unbalanced to a balanced pee valve, but are the physics that much different than an unbalanced? Thank you.

 

[PfcAJ]

Open the bolt to pee, close it when you're done. I like to pre-pee before descending to displace the air in the tube and make sure everything is plumbed right and there are no kinks or other issues. This is a worthwhile investment of your time.

There is no depth limit to p valves, and they don't need a check valve. Don't remove the bolt, if the cath pops off you'll flood your suit. I find balanced valve to be more trouble than they're worth.

 

[a22shady]

Why not just get a balanced Valve so you do not have to worry??

 

[Divin'Papaw]

Connect up ... open bolt ... pee ... then dive. Once you pee it purges the air, fills the line with pee and that's that. Water doesn't backflow up the line as it's already filled with a liquid. I have over 150 dives on mine and never an issue.

I leave the bolt in but open. I want it there so that I can close it if I suspect something's come unhooked.

I do flush mine at the end of each diving day with 50/50 white vinegar and water.

 

[TSandM]

The two biggest preventions of UTIs are avoiding backflow (no kinks, no peeing with the valve closed) and doing good hygiene on the tubing and valve. Ideally, that means flushing copiously with fresh water immediately after diving, and as soon as possible, flushing again with a disinfectant. I am using alcohol, which is not the most powerful antiseptic, but it doesn't harm any of the parts. Vinegar is a very poor disinfectant for p-valves, because if you think about it, organisms that grow in urine are used to an acidic environment.

 

[PfcAJ]

Why not just get a balanced Valve so you do not have to worry??

When (not if) the balance chamber fails, piss goes all over your leg. Gross. I prefer not to pee on my rather expensive undergarments.

 

[LiveBait]

Unbalanced vales are just a tube that connects to you and is directly open to the water. The only thing that keeps pee in and water out is the seal between you and the condom/catheter on one end and a bolt on the other. If your seal breaks you get wet if you loose the bolt and the seal breaks you get wet.

This is a good read about pee valves and possible problems.
Cave Diver's Forum - Cave Diving Resource

This has been recommended by others as a good disinfectant and, is mentioned in above article.
Durvet Inc 1 Gallon 001-0259 Chlorhexidine 2 Solution

Hope that helps.

Oh about the physics. I am sure someone will explain it better than I but, fluid is not compressible. So if you pee before you enter the water that takes all the air out of the line so when you open the valve (bolt) its already equalized. If you have air in there the water is going to try to push in and you will need to pee (push the water and air out). The deeper you are the hard this will be.

Also what I did to help understand the process...
Set your self up as if you are going to dive catheter and all but, don't fully done your suit so you can see everything happen.

Then unscrew the bolt or just take it out and pee.

Doing this I noticed that I needed to do a better job of putting the catheter on. I had a gap between my tip and the condom tip. This caused a balloon effect and made it easier to kink there. I also notice that it was less likely to have a blow out if I went for a little while and then stopped. Rather than doing a complete purge.

 

[a22shady]

When (not if) the balance chamber fails, piss goes all over your leg. Gross. I prefer not to pee on my rather expensive undergarments.

Well I am not sure how often they break, i am sure like anything it's possible but with that being said I have not seen lot's of posts with this being an Issue. I have only had my valve for around 30 dives so not many but have had no problems, Another buddy has had his for well over 100 dives with no issues, same goes for a few others. But I guess on the positive side if it does ever go It's a good thing i have the 4th Element Undergarments so they are washable...

 

[PfcAJ]

I've seen it a few times. Its real. And gross. I have an unbalanced valve on one of my suits and a Halcyon valve on the other. The H one leaks peepee from time to time. Not a lot, just enough to stank up the leg of my 400g.

Salt deposits from your piss get all up in that balance valve over time since the balance valve doesn't really get much water flow through it when you rinse out the rest of the system. Since it can fail, and its not really needed, I don't see them as an advantage.