Definitions

[GBT]

Could some explaing the difference between a unitank, fermenting tank and serving tank. Also what does one look for when purchasing any of the above.

Thanks.

[tarmadilo]

A unitank is both fermenter and aging tank, it is a closed fermenter with a sharp conical bottom that makes it possible to easily drain out the yeast after you chill the beer down after fermentation. They have c.i.p. (clean-in-place sprayballs) systems, which means you don't have to climb in and clean them, most of the time. It's also easy to carbonate the beer naturally since it's a closed tank.

A regular fermenter would have a flatter bottom and you'd want to transfer the beer out of it off the yeast into a separate aging tank. Open-top fermenters are useful with some ale yeasts, but these fermenters often require hand-cleaning.

A serving tank would be a tank that you'd transfer the beer into after it's aged, often filtering it and possibly adding carbonation to it as you transfer it. These tanks can also have carbonating stones as well.

Serving tanks and aging tanks can be interchangeable.

As for what one looks for, I look for polished welds, good quality doors and gaskets, c.i.p. systems, and pressure relief valves

Cheers, Tim

[GBT]

Wow,

Thanks for the detailed response!! These forums rock!

Just a quick follow up. Do most small brewers use unitanks? What are the adv/disadv? Thanks again.

Glen

[tarmadilo]

Seems to me that most new systems being fabricated these days have unitanks. It can be considerably cheaper to use converted dairy tanks as fermenters (which I've done as well), and if a brewer is making English-style ales an open-top fermenter is handy for harvesting yeast from the top of the beer.

I personally really like unitanks. Lots of flexibility, you don't have to transfer the beer for aging, easy to clean, easy to harvest yeast from the bottom, they're vertical so they don't take up a lot of room compared to a dairy tank.

Cheers, Tim

[GBT]

Again, thanks for the info.

I have an opportunity to acquire four stainless steel containers (which seem to be about the 15bbl range) that were previously used to make cosmetics. There are several valves at the bottom of the tanks and the main access to the tanks is from above.

My questions are as follows:

1. How do I determine if they are CIP or CIP compatible?

2. How do I regulate the pressure (of those used as fermenters)?

3. How do I regulate the temp?

Sorry if these questions show my lack of experience or knowledge, but I am new at this. Thanks,

Glen

[tarmadilo]

You can't become a Jedi brewer without asking questions!

> 1. How do I determine if they are CIP or CIP compatible?

CIP (Clean In Place) systems use a sprayball at the end of a tube, usually placed a foot or so from the top of a tank. These can either be welded into the tank, or more commonly attached to a fitting on top that can be removed. Depending on what kind of fittings/openings you have, it can be as easy as just getting a sprayball to fit to an existing opening, or have something welded on. Either way, not a big problem!

> 2. How do I regulate the pressure (of those used as fermenters)?

First you need to figure out if you want any pressure at all! You don't NEED to carbonate in your fermenters, and it's actually quite common to let the CO2 bleed off entirely, and carbonate the beer afterwards by means of carbonating stones either in-line after filtering, or in your serving tanks. Your tanks might not be rated for any pressure, and you want to be careful! To keep pressure from building up, you need to make sure there's a way of venting the gasses while fermenting. With closed fermenters, there's usually a pipe that goes up to the top and into the fermenter (and that's a great place to put your CIP sprayball!). You attach a short hose from this pipe into a bucket with some sanitizer, and presto, you have an airlock/bleed off.

> 3. How do I regulate the temp?

Fermenters are usually double-walled with some kind of jacket that you can run coolant through, with temperature-control valves and temperature probes inside the tank. Of course, you also need a chiller for the coolant. If your tanks are single-wall, it'll be difficult to use them as fermenters, although it's been done (you need to put them in a climate-controlled room, and chill the whole room to a temperature that'll keep the yeast happy, not an easy or cheap thing to do!). Or, you could have them jacketted, not cheap, but do-able.

Cheers, Tim

[dick murton]

Just a couple more thoughts on CIP compatability.

If you are using caustic based detergents to clean the tanks, as I expect you will, then the tank needs to be able to breathe freely, so you don't suck it in. You may have to clean with the door open, or fit an anti vac valve (expensive, and from expereince not 100% reliable) The tank should be free draining, i.e. have a decent dish bottom or conical bottom, with the outlet AT THE LOWEST POINT (surprising how many tanks don't) Flat bottom vessels are much more difficult to maintain in a hygienic condition.

If you want to apply any sort of pressure, then in the UK at least, and I am sure in N America as well, the tank needs to be pressure rated & insurance inspected to ensure it dosesn't go bang

Instead of wall cooling jackets you can use internal cooling coils, made from stainless or copper. Not recommended though as they are pigs to clean, and create blind areas if using CIP to clean the rest of the vessel. I don't recommend temperature control in a temperature controlled room - basically it won't work unless all your FVs are at the same stage, and even then heat transfer is too slow.

Lag the vessels, even if you do it yourself with mineral wall like you use in the home. It will make temperature control possible.

Cheers

[GBT]

Thanks for the feedback guys. This is an invaluable forum!

[Sir Brewsalot]

Originally posted by dick murton


Lag the vessels, even if you do it yourself with mineral wall like you use in the home. It will make temperature control possible.

Cheers

Hi,
I really appreciate all the good info too. Coupla questions though. What does "lag" mean in the context above, and what is the "mineral wall" you are referring to? Perhaps it's a bit of UK lingo that I'm not familiar with.

Regards from the colonies,
S

[dick murton]

Insulate the vessel, just like you would the roof space in your house. One cheap option is to use the same material, which can be glass fibre matting, or rockwool matting (mineral wool). There are specialist insulation materials, but these will cost you more money - but really should be used for long term effective insulation. Ensure the lagging is encapsulated in plastic sheeting or similar impervious material to prevent it getting damp.

Whichever you use, ensure the metal of the tank is painted with some sort of impervious, chloride free paint, bitumen type, to ensure that if the insulation does get wet or damp, as it is liable to, the chlorides contained in the insulation do not concentrate on the stainless surface and eventually (or perhaps even quite quickly) cause pitting corrosion leading to stress corrosion cracking or full penetration of the steel. Stainless steel is only corrosion resistant providing the chromium oxide layer remains intact, and ionic chlorine (chlorides) is a very agressive attacker. Getting perforated or cracked tanks is no joke - I have practically been able to shower under some tanks with pinhole leaks - admittedly from using raw hypochlorite as the terminal sterilant and allowing the puddles to dry out (before I started at the place - so not my fault I am pleased to say).

Hope this helps

Cheers

[Sir Brewsalot]

Thanks Dick.

I think I've got it:
Lag=insulate
Mineral wall=something like what we'd call fiberglass on this side of the pond

Never considered that contact with the tank would cause pitting, but it makes complete sense the way you've described it here.

Many thanks,
S