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mikedeich
01-18-2013, 08:07 AM
quick question for anyone who can set me straight. My brewpub recently added a walkin and we have begun serving only through kegs. For lack of a better option, fancy keg cleaners and the like, for cleaning the kegs I have essentially filled a barrel or so of hot water & caustic or acid into a brite tank, pressurized said brite tank, filling each keg with a small amount of chemical and shaking each vigorously by hand....then giving them a hot water rinse at a McGyver like sink area with connections to rinse/pressurize. Now Im second guessing myself because I seem to remember that CO2 neutralizes caustic. So is this method essentially worthless when done with caustic? Or does it take some time to neutralize? These are used kegs so I want to make sure they get as clean as possible obviously. Any input appreciated. Cheers.

BonedaleBeer
01-18-2013, 09:19 AM
Yep - Caustic is neutralized by CO2.

Cool video showing the reaction!

http://www.youtube.com/watch?v=GZdgvRgtJnI

Packey
01-19-2013, 03:43 PM
I was told that mixing CO2 and caustic would cause a tank to explode. Anyone out there hear the same?

a10t2
01-19-2013, 03:59 PM
It would actually implode, if anything. The gaseous CO2 is being consumed by the reaction, resulting in a net negative pressure.

Packey
01-19-2013, 04:46 PM
That was it. Explode or implode. Either way, someone can get hurt.

TL Services
01-20-2013, 01:24 AM
Caustic is sodium hydroxide (NaOH) and this will react with CO2 to produce both sodium carbonate (Na2CO3) and sodium bicarbonate (NaHCO3); the latter still have some detergent effect although not as great as NaOH.

The relative amount of the two products is dependent on the conditions , eg. temperature, etc.

Most automated CIP systems reuse caustic solution many times and only discard when the amount of NaOH drops below a certain level and/or the reaction products are higher than 'spec'. I spent many happy years analysing CIP samples back in my 'lab rat' days :)

IF this reaction takes place in a closed vessel with a significant quantity of CO2 present in it and IF the vessel has no form of anti-vac, then it is POSSIBLE the vessel will collapse in as the CO2 reacts, as the external air pressure will be lower than internal pressure.

Tank collapse is very rare and only tends to occur when caustic is sprayed into a CO2-filled tank through a sprayball. This is because the fine droplets allow a high surface area and thus a fast reaction. As above, collapse also needs this to happen in a tanks where the anti-vac is stuck or which doesn't have an anti-vac valve.

For a start, if you're pressurising your tank then the fact that your are putting gas in will prevent implosion; furthermore I would suspect that you're using the caustic solution pretty-much immediately, so it's not likely to have fully reacted, therefore what goes into your kegs will be cleaning them.

If your procedure is cleaning your kegs effectively, such that you're having no problems once they're reused, then clearly it's working.

You could look at using a plastic transitank for caustic make-up, then either gravity feed into your kegs or pressurise with air. This would get away from any possibility of excessive CO2 compromising the process and would also eliminate any slight chance of someone accidentally using the brite tank for beer before it's been emptied & rinsed.

Hope that helps!

Fullcourt
01-23-2013, 05:38 PM
cleaning a stainless vessel with caustic in the presence of CO2 will cause beerstone to form on the sides of the vessel. That is why keg cleaning machines use compressed air to blow out whatever is in the dirty keg, then after cleaning and sanitizing, CO2 is introduced into the clean keg.

TL Services
01-23-2013, 11:40 PM
Beerstone is calcium oxalate, so will not form simply by cleaning with caustic (sodium hydroxide) itself in the presence of CO2. However if the caustic solution has been made up with hard water, containing calcium salts, then oxalate can form as a result.

Fullcourt
01-29-2013, 12:34 AM
Beerstone is calcium oxalate, so will not form simply by cleaning with caustic (sodium hydroxide) itself in the presence of CO2. However if the caustic solution has been made up with hard water, containing calcium salts, then oxalate can form as a result.
KWLSD is correct, I stand corrected. You should always clean with soft water.
There is a danger of implosion, I have seen fermenters that were subjected to caustic and CO2 that looked like the Jolly Green Giant squeezed it like a toothpaste tube.

TL Services
01-29-2013, 06:16 AM
I have seen fermenters that were subjected to caustic and CO2 that looked like the Jolly Green Giant squeezed it like a toothpaste tube.

Absolutely! The most impressive - if impressive is the right word - I ever saw was a 2500-barrel cylindro-conical that had gone. It had a smaller waist than a 1950's burlesque starlet!

dick murton
02-01-2015, 04:15 AM
I'm looking for some images of FVs (or similar) sucked in due to thermal contraction (no vacuum relief) or chemical reaction such as caustic / CO2, for a training session I am doing.

Anyone able to provide me with a couple of suitably catastrophic ones? Unfortunately the last ones I saw were in the days before camera phones and I didn't always have a normal camera to hand.

Thanks

BrewinLou
02-02-2015, 07:33 AM
http://discussions.probrewer.com/attachment.php?attachmentid=13132&d=1382999905

There is one.

dick murton
02-02-2015, 08:51 AM
Great.

Thanks very much. I remember seeing this before - just forgot about it.

This will do fine

Cheers