Options for Keeping CELLS DRY

[broncobowsher]

A momentary spike is no big deal. Sustained high PPO2 is a different story.
What I am talking about is simple. At 30' and time to move to 20'. A quick blast of O2, a couple of breaths to get it past the cells, verify they still spike past the 1.6 mark. Inside of 30 seconds of initiating this you are ascending and the PPO2 is back down again. No need for 100% flush of O2 in the loop to check for limiting. If you are so close on your O2 units you can't take a 30 second blast of O2, there are other issues with your planning.

I'm not talking about spiking the O2 at 30' then hanging around for 15 minutes at that depth and super high PPO2. Check, get out of there.

 

[tbone1004]

A momentary spike is no big deal. Sustained high PPO2 is a different story.
What I am talking about is simple. At 30' and time to move to 20'. A quick blast of O2, a couple of breaths to get it past the cells, verify they still spike past the 1.6 mark. Inside of 30 seconds of initiating this you are ascending and the PPO2 is back down again. No need for 100% flush of O2 in the loop to check for limiting. If you are so close on your O2 units you can't take a 30 second blast of O2, there are other issues with your planning.

I'm not talking about spiking the O2 at 30' then hanging around for 15 minutes at that depth and super high PPO2. Check, get out of there.

I was taught to do that in my mod1 class. As you are ready to leave 30ft, do a quick o2 flush to get up past 1.6 on your way to 20ft.

 

[broncobowsher]

I was taught to do that in my mod1 class. As you are ready to leave 30ft, do a quick o2 flush to get up past 1.6 on your way to 20ft.

Exactly. If it wasn't taught specifically that way, it was figured out on my own while still in class. Specifically to check the cells at the end of the dive after they have been stressed.

 

[v101]

Appreciate everyone comments/suggestions so far -
I fixed the post, thanks for correcting me. I have the OPV plugged. I did notice water leaking in from this. Plugged that off and not had an issue with moisture getting in from that area.

The cells are the same type of cells, they weren't all put in at the same time. I typically replace my cells when the MV gets low, and my linearity checks start falling down. I had 1 cell that was only 6 months old and it was reading lower also during this dive..

I can get the numbers from the pre-dive and post here if that will help to review that data.

in between dives, I am leaving the unit on a picnic table. the temps from the air this time of year were warmer, so it's possible some condensation happened
If I am shaking some moisture from my counter lung in between dives, and squeezing the loops to get moisture out from those also, granted some is there in there.

I will try that method of using the rubber parts from the end's of hoses.

unclear if anyone has tested or tried products like this, here is another video

I am in process of obtaining some samples and going to see the WOB is like with this in use.

 

[tbone1004]

@v101 are you using cells with a membrane on them? Last i checked Edd wasn't using cells with membranes, that would certainly contribute

 

[rjack321]

The top of my sensor can is normally dry as a bone on a first dive and can get a bit moist on a second but still not seeing the cell issue described. If you are setting up outside in heat and humidity versus inside in AC, the cool water can create some condensation if the cans, loop, CL are full of atmospheric warm moist air. But... your pre dive should have replaced all that with gas from cylinders that is dry. If I leave the unit sit in the sun between dives and the unit heats up.. it will add moisture to the lids from whatever moisture is in the unit from expiration or any accidental small ingress.

I can say with certainty that diving the sidewinder in 3-4C water with or without the scrubber heaters turned on is VERY soggy on the inhale side. The scrubber heaters probably make it worse but its hard to quantify.

There is just a ton of condensation on the inhale hose that runs back into the inhale head. It ends up soaking the lower half of the inhale canister's sorb from the top down. There's just nowhere else for it to go - although with some strategic DSV tilting you can sort of get some of the liquid into the exhale side of the loop.

@v101 what's your water temp?

 

[v101]

This past trip I was in a quarry, the temps above 20' were 75 degrees F. below 20' it dropped off, the coldest i was in was around 50, but not long for the 2nd dive. mostly was doing some practice drills around 30-40' so the temps werent that cold. computer shows temps there were around 65 degrees.

usually in FL where I dive the temps are 68. I have the same problem on longer dives in FL also.

 

[v101]

@tbone1004
the cells I am using are:
Analytical Industries (AI) PSR-11-39-MD
these have a Hydrophobic membrane

 

[tbone1004]

@v101 try doing a dil flush every 20-30 mins or so to lower the humidity in the loop. The loop is always at 100% relative humidity, so it will always condense, but dil flushes semi frequently have helped for me

 

[Brad_Horn]

Specific design of cell and Orientation of cell in use and Ability for the cell face to trap water all have a factor.
Seems the biggest win is a cell without threading on the front, that has a flat face, orientated at about 45' to the divers orientation no matter if vertical or horizontal, at the top of the loop.

Most means to resolve the cell design issues are covered in https://www.deeplife.co.uk/or_files/DV_O2_cell_study_E4_160415.pdf

You should find how the manufacturer has tested and designed out this specific risk in your rebreathers FMECA