Reusing a scrubber?

[kensuf]

I figure it's my turn for starting a topic of discussion.

Do you reuse a scrubber from one day to the next? Or do you always start each day with a fresh stack? Under what circumstances do you bin it, and what circumstances will you let it ride? What size scrubber do you use and how does that play into your decision making?

On my side..

My default go-to can is a 5.5# radial (on my Fathom) or the 5.5# axial on my SF2. My rule of thumb is any time I'm diving deep (>200') I start with a fresh pack, but I'm comfortable with re-using a scrubber for two days in a row for shallower dives given certain criteria.

Any time I've put more than 3 or 4 hours on the scrubber, I bin it, period. I have put over 7 hours on these scrubbers (multiple times), but they were single dives with the majority of the time (more than half) being on deco. Any time I'm over 3 or 4 hours, I consider it cashed enough that I have zero interest in re-using it.

Any time I'm debating about starting with a USED scrubber and I know my dive plan will get me above 4 hours total on the scrubber, I bin it and repack. So basically, my rule of thumb is roughly 2x 2 hour dives and I'm comfortable reusing a scrubber two days in a row, after that I'm dumping it and starting fresh.

 

[Caveeagle]

I have been using EAC cartridges, and nothing really deep for now. I have used the same EAC for multiple dives in one day where the total time was well under 4hrs.

For different days, I log time and date on the EAC. Then I bag, can and store in an air tight container if I plan to re-use. I can say I have used partially spent EACs that were a couple weeks old, but toss them if they are much beyond that.

 

[rjack321]

My meg and my sidewinder are both axials and both hold about 6.5lbs of sorb.

I am willing to do 5hrs as one dive on either - on a dive like that a big chunk is going to be deco so I am not as worried about high workload breakthrough on the dwindling scrubber.

Otherwise in cold water (mid 40s to mid 50s F), I am willing to do up to 4 hrs of recreational-ish diving on either. Usually no deeper than 100ft or so. Any combination of dives but most common would be 3 dives each a little over an hour. Total = 4hrs

For deeper dives with ~90-120min runtimes (150-220ft) I am willing to do 2 dives in a day. Then its changed. If I only do 1 dive and day 2 is at all uncertain I change it. I would do a tech dive then 2 shallow dives on day 2 (max 4 hrs combined).

The sidewinder has a scrubber heater which basically dumps 100-330Wh of energy into heating up the sorb - it gets pretty hot actually. 145F if its just static in my refrigerator. I don't alter my duration based on that just use it to help keep me warm and as extra insurance on seriously cold dives (high 30s) that my scrubber is sound for 4-5hrs.

The sidewinder has no water trapping ability. If the CL has more than average amount (50mL) of condensation in it I dump the sorb and repack no matter how much time I have.

In FL and warm (70F) water I usually only do one long 3 to 5 hour dive. I always dump and repack unless I for sure know the next day will be short and shallow (like a 30-45min gear check dive)

 

[davehicks]

There are a couple of well done studies on this question. See below:
Sorb Storage: New research released!

Summary: No problem or penalty for storing and re-using scrubber before it's fully depleted. Keep track of the run time and keep it stored in a SEALED ziplock or in the airtight unit. Do NOT let it dry out as that will reduce it's effectiveness.

Obviously if you only have 1 hour of run time left you should not start a 2 hour dive. I mostly do 60 - 90 minute dives and if I just do a single 1 hour shore dive on a fresh scrubber I have no issues with going out to do another 1 or 2 hours of diving a few days or a few weeks later. (I mostly dive cold water and target 3-4 hours on fresh scrubber in my Kiss Spirit)

 

[rjack321]

I'm sure @kensuf is familiar with that study but unfortunately it doesn't address duration, temp, and depth. It's just examining storage. Not "how long it lasts".
Hence the CO2 hit at 300ft he brought up in another thread.

Our conditions in Puget Sound are a lot closer to the CE test conditions. Scrubbers last much longer in 70f FL waters, but how much longer and at what depth is an enduring mystery.

 

[JonG1]

I can't recall where I read it but a recent study demonstrated that at normal respiratory rates, scrubber duration as prescribed by manufacturers could be exceeded.

However breakthrough could occur rapidly and without warning if respiratory rates were increased even modestly.

This could be for a myriad of reasons, but scooter failure, inc. equipment drag as stages are accumulated or even swimming to the boat post deco are all obvious trigger events.

Wish I could recall where I read it now..

 

[kensuf]

Obviously there are a large number of variables that will impact duration of any scrubber, water temperature and workload being the two biggest. But, as you said, when it's done, breakthough can occur rapidly and without warning.

I'm really simply curious what people are doing out there.

 

[JonG1]

JFTR if I am going to re-use I don't exceed a maximum of 3 hours, but would go up to 4 hours on a single exposure.

No hard and fast rules on re-use I just gauge the dives it's been used on, duration and forthcoming profile make a decision from there

 

[jgttrey]

my rule of thumb is roughly 2x 2 hour dives and I'm comfortable reusing a scrubber two days in a row, after that I'm dumping it and starting fresh.

This describes me with the proviso that I'll dump and repack if Dive #2 is going to be more than, say, 200', or in an overhead, or if conditions are crummy or anything else. Open water and benign conditions, I'm fine with starting a reasonable dive with 2 hours on the can (5.5 lb radial).

I'm not making the kind of dives that most in this thread are -- mostly open water ocean or wreck, not cave. If dive #2 was a penetration of any significance, I'd dump and repack. For tootling around the outside and poking my head in at reasonable depths, I'm fine with having two hours on the can already.

 

[rjack321]

JFTR if I am going to re-use I don't exceed a maximum of 3 hours, but would go up to 4 hours on a single exposure.

No hard and fast rules on re-use I just gauge the dives it's been used on, duration and forthcoming profile make a decision from there

what unit is this? scrubber size?