Open fermentation: How much CO2...

[Jon474]

I am currently drawing up plans for a 10bbl brewery. I want to experiment with open fermentation but a comment by Ted Bruning has caught my eye. In his book, The Microbrewers' Handbook, page 70, he reports that Richard from the Tring Brewery suggests that a drawback with open fermentation is the need for excellent ventilation because of the levels of CO2 produced. I presume it is then Ted himself who states that even low doses of CO2 can be dangerous.

How much CO2 does a typical OG 1.042 beer in a 2.5m x 2.0m x 0.5m profile open fermentation vessel (2500 litres) actually produce? In one hour? Over twelve hours? How can you work this out? Is it possible to work out the typical rate of CO2 production in fermenting beer?

Is it likely to be produced at a rate hazardous to health with only normal ventilation?

Questions. Questions.

Cheers
Jon

 

[Mephistopholes]

10bbl!! thats some big homebrew right there.

how big is the room that you're fermenting in?

 

[Jon474]

It will be a proper microbrewery. 10bbl is the scale I would really like but I accept it might have to be 6bbl. It's all about the money at this stage.

It's a desk top exercise at the minute - I am doing all my planning, working out what kit I need and where it needs to go, getting the brewery layout sorted out on paper, sourcing suppliers, costing scaled up recipes, sorting out the finances, getting the process flows drawn up, looking for premises, registering with HMRC, market research etc. The list seems endless but very satisfying to do.

Still homebrewing, because I love it and how else can I get some recipes designed and tested?
Jon

 

[Aleman]

It produces enough CO2 to be lethal!

There are several recorded cases of people becoming overcome by CO2 fumes, and falling into an open fermenter and drowning . . . HnS nightmare

You will need proper ventilation accept it

 

[Jon474]

It's funny how life goes, isn't it? I mean this. It is genuinely weird.

I was supping my pint of Marston's Pedigree in my local tonight when I got chatting to a man who makes CO2 analysers for pub cellars (as well as for deep sea diving bells). I now know all about the biochemistry of CO2 poisoning - 5,000 ppm = burning sensation in the nose, 15,000 ppm = death. Normal air contains c380 ppm (I think I remember that being the number). That's the easy stuff. I also know that excess CO2 affects the blood serum - whereas carbon monoxide affects haemoglobin - and because after exposure to excess CO2 the blood serum, which normally runs around your body capturing the expelled CO2 from your cells, now has a higher concentration of CO2 than the cells which are trying to expel their CO2 into the blood steam (and so cannot do it) you get a cessation of the metabolism of the cell...which leads eventually to cell death, leading ultimately to your death. Actually, leading to your death very quickly. As Aleman says, the main risk in these scenarios is that you fall INTO the zone of saturated CO2 and are rendered unconscious so quickly that you cannot even attempt to save yourself...and, in addition, you put at risk those who come in to rescue you because they have to move into the danger zone to reach you. Apparently, unconsciousness is frighteningly quick...it takes just seconds.

Carbon monoxide on the other hand is all about the CO hanging on very tightly to the oxygen in your haemoglobin and not giving it up to the oxygen-depleted cells in your body that crave it. That's why you go red...oxygen enriched haemoglobin which cannot dump its oxygen.

However, more importantly for me, I also now know about how to mitigate the lethality of CO2 (howsoever it is derived - CO2 keg in a pub, or CO2 production from an open fermenter) in a positive air pressure clean room.

I would still like to know what the necessary calculations are for assessing how much CO2 a 2,500 litre open fermenter of 1.042 beer produces...but I will find out. I am confident about this. All I need to do is go back to the pub tomorrow night. For sure, someone will be there to give me the answer.

Brewing is truly a fascinating subject. Who knows where it will lead me tomorrow?

Take care
Jon

 

[Mephistopholes]

I'm with Aleman on this (i wonder how many times thats been typed on the forums)

Rather than worry about the exact figures of how much co2 is being expelled from the fermentors, just look into extraction devices instead. I had a look round redemption brewery in tottenham recently and they have two 10 bbl fermentors in a seperate room. to give this in terms of scale they could probably fit 12 fermentors in this room, its pretty big. They are still a fledgling brewery so are only running 1 fermentor at a time. The extraction is rigged so that when the lights are turned on in the room it comes on automatically. I would think any smaller a room though and you would need to run it whenever you have beer fermenting. we're talking potentially fatal here. its not an area where you can cut cost. just get the extraction.

On another note i've heard the biggest headache for brewery builds is drainage. its all about the drainage. apparently one of the first things that needs to be considered and implemented. remember you're gonna be using a lot of water.


Good luck with the planning :thumb: