Partially Used Scrubber

[Olaf Bontes]

I wonder what the bacterial growth will be during the storage time after usage. Store it in the cooler to prevent bacteria from growing?

If I think back of the research done on OC regulators I wouldn't leave it that long after breathing through it and clean it well.

 

[Baron015]

pH 12-14 tough bacteria !

 

[rjack]

I wonder what the bacterial growth will be during the storage time after usage. Store it in the cooler to prevent bacteria from growing?

If I think back of the research done on OC regulators I wouldn't leave it that long after breathing through it and clean it well.

Bacterial growth doesn't appear to pose a problem though. At least not for most people most of the time. Going 6 months would be unusual. Probably 80-90% of the members here will store used sorb a month though. Does not seem to cause infections or cause any problems. So I'm not sure there's a problem to be solved.

 

[lizardland]

Bacterial growth doesn't appear to pose a problem though. At least not for most people most of the time. Going 6 months would be unusual. Probably 80-90% of the members here will store used sorb a month though. Does not seem to cause infections or cause any problems. So I'm not sure there's a problem to be solved.

True but there's the law of unforeseen consequences. If the study shows there is no degradation in performance with extended periods in storage then people will end up doing it. If that then leads to bacteria or other nasties growing there then it's good to know in advance. And maybe a reason not to.

As I said earlier, I had ill effects after using a can that had been stored. I've got two scrubber cartridges for my mk15 and I'll sometimes leave one prepped and unused or swap out a part used one if I've got a bigger dive coming up that a fresh fill would be more appropriate for.

I've seen stuff at work growing in very aggressive environments. It wouldn't surprise me to see a scrubber being able to host bugs.

 

[Simon Mitchell]

True but there's the law of unforeseen consequences. If the study shows there is no degradation in performance with extended periods in storage then people will end up doing it. If that then leads to bacteria or other nasties growing there then it's good to know in advance. And maybe a reason not to.

Hello,

This is a very useful discussion, thank you. I must admit that we did not think of the bacteriology point.

I am sceptical about bug growth in soda lime during storage (for the same reasons as stated by the Baron), but your point is very well made.

Our planned storage period is a month. We are only doing a limited number of human studies (most of it will be bench test with a breathing machine). The bug problem would be more likely to be an issue in the human studies where respiratory bacteria could conceivably seed the scrubber during the first use and then grow during storage. I am forwarding a link to this thread to Neal Pollock and we will think about doing some cultures from the scrubbers before and after the first and second use.

Thanks again,

Simon M

 

[rjack]

You might want to collect multiple cultures at 1,3, and 6 months. For the very reason lizard states, if you don't find an issue at one month people will extrapolate that out to some untested time. If you have the resources, testing beyond typical (current) usage patterns might he helpful to try to nail down how long is too long.

 

[Randy Thornton]

You might want to collect multiple cultures at 1,3, and 6 months. For the very reason lizard states, if you don't find an issue at one month people will extrapolate that out to some untested time. If you have the resources, testing beyond typical (current) usage patterns might he helpful to try to nail down how long is too long.

We also need to consider the fact that many people leave their sorb packed in the scrubber/canister sealed inside their rebreathers. Even if the sorb is so caustic that the pathogens can't survive, that doesn't mean the rebreather loop itself is free of pathogens formed during the time the loop is sealed for days on end.

 

[lizardland]

Hello,

This is a very useful discussion, thank you. I must admit that we did not think of the bacteriology point.

I am sceptical about bug growth in soda lime during storage (for the same reasons as stated by the Baron), but your point is very well made.

Our planned storage period is a month. We are only doing a limited number of human studies (most of it will be bench test with a breathing machine). The bug problem would be more likely to be an issue in the human studies where respiratory bacteria could conceivably seed the scrubber during the first use and then grow during storage. I am forwarding a link to this thread to Neal Pollock and we will think about doing some cultures from the scrubbers before and after the first and second use.

Thanks again,

Simon M

I only raised it as I've twice had chesty symptoms soon after using part used scrubbers after a winter lay up. I used to be sceptical of stuff living in there. My day job used to be designing waste processing plants and I've seen "stuff" (not a biologist) growing in caustic enough environments that the atmosphere was eating through steel cladding. I'd love to know if it was just my paranoia or if there was any truth to it. I know, start the season with fresh lime... I'm Scottish, throwing perfectly good, five month old, partially used lime away doesnt come naturally

 

[Brad_Horn]

Our planned storage period is a month. We are only doing a limited number of human studies (most of it will be bench test with a breathing machine).

Simon, Looks like some interesting testing. If I may:
What type/brand of scrubber media are you using for the trial?
Will you be comparing the difference across type and brand as well?
Will you compare changes in WOB etc, from moisture and clumping differences?

Additionally, have you reached out to the individual companies to see what data they already have on hand to enable inclusion alongside your own trial results?
I know for a fact that Micropore with their EACs for example have a LOT of data from trials covering specifically this topic (for very good reason) and if you can talk them out of some of it, that might significantly value add to the depth of results you end up with for very little additional cost. You can get hold of Micropore at http://spiralith.com/

Regards
Brad

 

[AndrewDonn]

This sounds like some very interesting and overdue testing. From the description it sounds like the focus is going to be on scrubber duration but it would be great to see some investigation into the creepy - crawley issue. I would be surprised to see a difference in the durations but it would be great to have test data.

Another good data point would be to include WOB if possible to address the caking issue.

 

[AndrewDonn]

I know that a lot of divers are taught and use the remove excess water and store in a sealed bag/Tupperware method but I've always thought that this is a terrible idea. The scrubber still has moisture in it and now you are sealing in an dark, damp environment. It sounds like the perfect recipe for bacterial and fungal growth. The high alkalinity in the bed itself would probably inhibit growth but there are plenty of regions outside the actual bed but still in the scrubber canister where things could grow like the moisture taps, outside of the can and internal passageways.

I store partially used scrubbers all the time but they get dried completely. Most of the time it just sits on the bench completely aired out until it's next use. That is in the air conditioned house.

 

[MeRodent]

I store partially used scrubbers all the time but they get dried completely. Most of the time it just sits on the bench completely aired out until it's next use. That is in the air conditioned house.

I'd actually like to see some validation regarding moisture levels depending on pre-storage treatment.

ie which method is more likely to result in the appropriate level of moisture in the canister.

As storage conditions are important for moisture levels and moisture is likely to have an effect on the scrubber efficiency I'd suspect it's an important component of the equation.

 

[nickb]

I store partially used scrubbers all the time but they get dried completely. Most of the time it just sits on the bench completely aired out until it's next use. That is in the air conditioned house.

AIUI, the scrubber material has around 20% water content and this is vital for initiating the chemical reaction. Drying it out completely would be a big mistake.

I too leave my scrubber packed and stood on a shelf in my workshop after only wiping-off the excess water.

I agree about not sealing it up in an airtight container, that sounds like a recipe for all sorts of nasty anaerobic growth.

 

[trebor]

The diving this year for me has been sporadic so partially used scrubbers are left around but I usually forget the numbers (hours left) so just bin it and start again

 

[matt]

The diving this year for me has been sporadic so partially used scrubbers are left around but I usually forget the numbers (hours left) so just bin it and start again

Logbook.

 

[nickb]

The diving this year for me has been sporadic so partially used scrubbers are left around but I usually forget the numbers (hours left) so just bin it and start again

Logbook.

I have a strip of gaffer tape on the scrubber and write the dive time(s) on it. Log book no good if you can't remember which dives were done on that fill. Rob needs all the help he can get

 

[matt]

I have a strip of gaffer tape on the scrubber and write the dive time(s) on it. Log book no good if you can't remember which dives were done on that fill. Rob needs all the help he can get

All systems are a waste of time if you can't manage them. If you can't recall when the dive was done on the scrubber then how do you know you bothered to update the tape?

If in doubt I would chuck it out, of course.

Matt.

 

[MeRodent]

All systems are a waste of time if you can't manage them. If you can't recall when the dive was done on the scrubber then how do you know you bothered to update the tape?

By dating the tape when you write the scrubber times.

 

[matt]

By dating the tape when you write the scrubber times.

I don't see how the location of the note makes much difference. Log book or tape - if you don't write it then they are both the same.

I can see in the log book if the scrubber was new or not by looking at the tempstick, so it's unlikely a mistake would be genuinely made without incompetence getting in the way.

To that end, if I do not like what I see I chuck it out.

Matt.

 

[nickb]

I don't see how the location of the note makes much difference. Log book or tape - if you don't write it then they are both the same.

The tape is right there on the scrubber and I always remove the scrubber at the end of the day to dry the head. Can't help but see it.

I don't keep a log book, but if I did it would require an extra step.