Max time on Sorb?

NorthWoodsDiver

I am looking at buying an evo (and doing the training of course) but The biggest setback for me is scrubber size. I can see myself doing dives that are 3 or 4 hrs long (including deco of course) and the scrubber rating is only 3hrs. Now I know that number is directly related to CO2 not time and CO2 production will be different with every dive and every diver so I am just kinda looking for some numbers with approx times.

My dives primarily will be shorter as I live in minnesota where its cold 9 months out of the year and the bottom temp seldom exceeds 41 degrees F but there are times where I will be cave diving in mexico or wreck diving in florida or what ever where the water temps wont limit my dives but my scrubber will.

I also plan to do some deeper stuff (read below 200ft but no line has been drawn as to how much deeper) in both cold and warm water but obviously the cold will limit me so I dont plan to push scrubber life up here in the frigid north.

I am personally a fan of the vision setup which uses the Temp stick to monitor scrubber life span so thats partially why I settles on an AP unit over something with a larger canister. And since I wont be needing that large canister 90% of the time it would be wasted sorb anyway.

So I just want to find out kinda how long people get on average with there evo+ or equivalent volume of sorb.

netmage

A few general thoughts....

- the temp stick is not to be used as a sorb 'fuel gauge'.... It is a symptomatic indicator to show you the reaction is taking place, and a ballpark indicator where in the bed the reaction is occuring.... Much like color changing sorb...

- for your home turf diving, you'll want to stick to the official party line ratings, as those conditions are allot closer to the test criteria used when rating canisters than say my typical diving... (70-80 down in S. Florida)

Hopefully some folks diving the evo will chime in here w/ their real world scenarios...

O.C.Diver

While the temp stick concept is a nice idea, think of it more as a warning device as opposed to a dive planning tool. Most Rebreather are rated using the same test standards. So 2 units with 3 hour scrubbers should have similar scrubber durations as water temp and CO2 flow rates vary.

Regarding "wasted sorb":

Sorb is cheap, $10 to $15 a fill. Chose a Rebreather so that it will handle with a margin of safety, the most extreme dive you will likely do. Think of the remaining time on the sorb and remaining O2 in your tank as a huge safety factor. Visualize a silt out in the cave in Mexico. Wouldn't it be nice to know you have a 3 to 6 hour window to find your way out. Kind of like the rule of 3rds, only with a much bigger safety factor. Every time we go cave diving we start with fresh sorb and know we could double or more our run time as far as O2 and scrubber goes in an emergency.

Ted

NorthWoodsDiver

I didn't plan to dive around the temp stick by any means, but I do plan to use it and since the AP units are the only units I know of that have any system in place to monitor the scrubber I feel it worth while to by an AP product. I would rather know for sure that something is working at least partially than not know at all.

I'm not worried about sorb cost to much but if I plan to do 99 dives a year that are only 60-90 minutes long and 1 dive that is 240 minutes as it hardly pays to have a huge scrubber if I am dumping all the time. Of course I know I could just do 2 or 3 short dives on one fill also. If a larger canister was available for the evo just I would buy it just for those longer dives but right now no such product is available... not that I couldn't make one I suppose.

tekdiver170

I assume your looking at the Evolution Plus (Evolution bottles with an Inspiration cansister). With my Inspo I put 5 hours on it in 72 deg water with no issues, so 4 hours should be no real problem in cold water. But the Vision electronics are really nice to fly. Hope you have fun.

vtach67

The Sentinel from Closed Circuit Research also has a temp stick scrubber monitor in addition to software calculations based on gas consumption. It will give you a visual stack display along with a percentage of "life" left in the stack.

Freef

If they are available, have a look at the test criteria for the scrubber [temp, vO2 rate] and then decide for yourself if you are going to push the life.

Remember you can go semi closed on the CCR units, or use an external OC gas if you wish.

Attached is the pdf of test results on the Drager Dolphin and Ray SCR scrubbers.

Freef

Attached here....

Attached Images

Drager%20Cannister%20Duration.pdf (82.8 KB, 14 views)

PCDiver

The life of a scrubber depends on various factors including but not limited to
1. amount of O2 being metabolised in CO2
2. water temperature
3. dive profile

The last factor is often not mentioned but very important.

I personaly wouldn't have a problem with a 100 meter dive that includes 6 hours plus deco on my Inspiration. The reason is quite simple. Your CO2 production is minimal during the deco phase, which is the longest part of the dive.

I would never do six 1 hour dives where I'm swimming all the time.

4 hours on the Evo+; not a problem for most people. But as always, YMMV.

DWill

Ted, if you buy 8-12 for the HH from Sea Pearls (which I didn't) the cost per fill on the HH is about 36.00. Pretty much a rip when the true cost of 8-12 is about 100.00/keg.

Moral of that story is avoid XS and Sea Pearls...