"Cask conditioned", "nearly" real ale ...

Putting together some guidance on "cask conditioned" style home brew. So this is a small excerpt to get some feedback. The conclusions I based the article on may not meet with universal (any?) acceptance, because I don't ignore CO2 use and don't advocate what I believe are the most popular containers to use for this: Polypins. ("Polypins" I regard as a good substitute to using "breathers" or "aspirators" and the excerpt doesn't flatter them either)...

Target
The aim is to maintain the minimum pressure that doesn’t result in beer “perceived as flat”. Many will perceive the freshly conditioned beer (with 1.1-1.3 volumes of CO2) as “flat”! The term “perceived as flat” isn’t obviously measurable, but it’s one that helped me understand what is needed to serve up home brew as “cask conditioned” yet keep it palatable for several weeks.

(attached image)

As soon as the beer is tapped the dissolved “volumes” of CO2 start falling away rapidly. For “real ale” open to the air the level of CO2 would keep falling until there is virtually none left, but the beer is all gone in 2 or 3 days thus avoiding this and the inevitable ruination. Those unsure of selling all their beer that quickly might try a “breather” providing a window of about 5-6 days to flog the beer before it is perceived as flat. Home brewers are unlikely to finish their beer even in that time so could try a “propane” regulator to help keep the beer with sufficient dissolved CO2 to never be regarded as “flat”. As a side effect, the slight positive pressure means we can use “corny” kegs!

No comments? I'm going to take this as my interpretation is accurate, helpful, un-contentious and nobody is confused by it. So I'll go ahead with the rest of it? I can't really believe nobody questions it because it took me long enough to gel it my head.

Some little extras:

"CO2 saturation at atmospheric pressure" is about 0.85-0.9 "volumes" of dissolved CO2: What your beer will contain at the end of fermentation if kept under airlock (under airlock at least towards the end of fermentation). It's also what a "breather" will help retain, or beer in an unpressured polypin, or beer in a pressure barrel after a day or so when all the pressure is gone. i.e. "Flat". The bottom line is zero dissolved CO2 as near as damn it (actually about 400ppm, the amount of CO2 in the air).

"CO2 level perceived as flat" is my own "invention", a level above "CO2 saturation..." that will vary a lot: High for drinkers of bottled and "keg" beer, low for "real ale" drinkers. The important conclusion here is that most "real ale" drinkers don't actually like drinking "flat" beer!

A LPG ("propane") regulator maintains 37mbar - 150mbar (0.5-2PSI). People are already using them (and me) but I don't hear any reports from them.

My understanding of what you have said is that cask ale is normally stored at low (or ambient) pressure, with low CO2 levels around the 'flat' marker.
To sustain dissolved CO2 levels just above 'flat' something like an LP gas regulator can be used.
Seems reasonable to me.
What seems to be missing though is the fact that when cask (low dissolved CO2) ales are traditionally served in pubs they are pumped by a beer engine or similar and the sparkler thingy on the dispenser introduces air which temporarily increases the dissolved gas levels, and gives a head on the pint, all of which is what the average drinker is looking for. Conversely if you serve beer gravity fed from a cask (similar to what you are indicating) its the same stuff but at least for me less palatable.
In other words its the beer engine that is the difference!

Thanks terrym,

Yeah, hand-pumps I do cover later, after all that is what I use. The turbulence they create serving beer does indeed create a "head" and adds a lot of subtle flavour changes too. I agree hand-pumps make all the difference, they are not just for show but are an important beer ingredient! But please, that "sparkler thingy", its biggest positive impact on my beer came when I threw it in the bin!

I wasn't suggesting cask ale is stored at ambient pressure (beer in casks does carbonate, to about 1.1 - 1.3 volumes of CO2, or 2-4PSI), but that it's served at ambient pressure. So cask beer starts loosing what little carbonation it has on first serving. "Breathers" slow that decline to "flat", LPG regulators slow, then stop that decline short of "flat". Or at least that's how I see it. CAMRA activists will howl, but then home brew shouldn't be in their sights.

Just one query ...

... how do you get a left-hand threaded propane regulator with a metal-to-metal seal to fit a right-hand threaded CO2 bottle with a rubber seal?

Aye, in the full article I do mention the dreaded "POL" couplers.

What I did a while back was cut the "POL" coupler off, and then fashion the remaining stump into a 3/8" "stem" to fit into a JG fitting. Tedious!

But if you look hard you can find regulators with BSP threads (here's one: http://www.gasproducts.co.uk/cgi-bin/sh000001.pl?REFPAGE=http%3a%2f%2fwww%2egasproducts%2eco%2euk%2f&WD=ha9606&PN=LPG_50%2d150_mbar_Comap_Propane_Gas_Regulator_%2d_Brooder%2ehtml%23aHA9606#aHA9606) and it's easy to find BSP adapters for JG stuff.

Cheers!

I'm not getting a lot of feedback! Let's see if I can stir it up a bit...

The keystone of this article is the idea of "CO2 level perceived as flat". Which doesn't mean literally "flat" (zero CO2 in the beer) but a level of dissolved CO2 that is too low to make the beer palatable. I developed this conclusion because "breathers" or "cask aspirators" are only thought to keep the beer for a few extra days (well its not going off, and oxygen can't get at it, so why the short keep?). And I do hear people saying contrary things like a "breather" keeps the beer for weeks. And my own experience with "polypins": Great for a couple of weeks then the beer becomes unpalatable. Even "poor man's" breathers - 37mbar LPG regulators - didn't keep the beer much better than "polypins". In my view. But the variable LPG regulators seem to keep the beer until its all gone!

So I proposed "CO2 level perceived as flat" as the means of explaining all this. And that means keeping home brew pressured to a minimum of 50-150mbar (0.75-2PSI-ish).

Is no-one going to shoot me down?

Dutto said:

Just one query ...

... how do you get a left-hand threaded propane regulator with a metal-to-metal seal to fit a right-hand threaded CO2 bottle with a rubber seal?

Click to expand...

Yikes! I've just noticed what you were proposing...

No, you can't attach the propane regulator to the CO2 bottle even after sorting out the dreaded "POL" coupler: The regulator will not handle the pressure of the CO2 bottle. It must have a "primary" set at about 1-4bar. I've attached an image from the rest of the article to dispel any confusion.

The hazards of posting an excerpt!

From a physical chemistry perspective, "perceived as flat" would be the point at which the beer no longer evolves gas, which as you say is when the carbonation volume drips below 1 (the head is almost 100% CO2 so maintains a 100% mole fraction of CO2 in equilibrium with the beer). When you drink the beer you're taking it from 13C to 35C, adding turbulence, and surface area to allow bubbles for form and 'fizz' in your mouth.

If you hook a keg upto an aspirator there's no (CO2 based) reason it shouldn't last any less time than it would in a corny. All it's doing is replicating the conditions in the keg when you swapped from a soft spike to a hard spike, for the whole volume of the cask.

But, I was under the impression that beer engines/hand pumps were a bit rubbish at preventing backflow, so over time you're constantly swilling old beer back into the lines and cask.


Solutions:
1) Keg it, regulate it to 1-2psi, and CAMRA be damned with their instance that no CO2 is used.
2) Cask it, but with a tap rather than a beer engine, and use an aspirator so there's no backflow and no air ingress.
3) There's a 'bag in a keg' that CAMRA have endorsed where the beer is in an internal bladder in the keg so you can put as much CO2 as you like outside the bag to push it up to the bar from the cellar without affecting the fizz.
4) Drink it quicker.

Thanks Spoon. That certainly tests my ideas! So here goes (many might want to skip over this: WARNING; techy counter-argument commencing...).

Spoon said:

From a physical chemistry perspective, "perceived as flat" would be the point at which the beer no longer evolves gas, which as you say is when the carbonation volume drips below 1 (the head is almost 100% CO2 so maintains a 100% mole fraction of CO2 in equilibrium with the beer). When you drink the beer you're taking it from 13C to 35C, adding turbulence, and surface area to allow bubbles for form and 'fizz' in your mouth.

Click to expand...

Two guys in a pub, one says "this beer is flat!", the other says "no its not!", so who's right? From a "perceived as" point of view they both are! From a physical chemistry perspective, the first is wrong! I used the word "perceived" because I didn't want to suggest right or wrong. I also tried to avoid scientific explanation because a lot of readers will switch to reading something else!

It is unfortunate that at room temperature and pressure, CO2 saturation in beer is pretty near 1 volume CO2 in 1 volume beer. Gives the wrong impression. And the explanation wont help most people.

Spoon said:

If you hook a keg upto an aspirator there's no (CO2 based) reason it shouldn't last any less time than it would in a corny. All it's doing is replicating the conditions in the keg when you swapped from a soft spike to a hard spike, for the whole volume of the cask.

Click to expand...

That's the basis of my methodology! An "aspirator" ("breather") will maintain zero PSI (psig in case anyone picks me up on it). CO2 saturation in beer at zero PSI is a bit less than 1 volume (at room temp.) so anything over that that the beer contains it will give up to the atmosphere (via the breather, which doesn't allow pressure in the keg to increase). The result: I and many others, perceive the beer as "flat".

This is presumably why "breathers" don't extend the life of beer more than a few days.

Spoon said:

But, I was under the impression that beer engines/hand pumps were a bit rubbish at preventing backflow, so over time you're constantly swilling old beer back into the lines and cask.

Click to expand...

I'm not really dealing with hand-pumps here, but: I guess that old hand-pumps were a bit leaky when it came to backflow. Hence (real) check valves came into play. Modern pumps I imagine are a lot better, and the hand-pump's "check-valve" has evolved into a "demand-valve" to prevent pressure pushing the beer out of the pump (rather than stop it going the other way).

The (as yet unpublished) section on hand pumps recommends a "demand valve" because the solution also recommends maintaining a very small positive pressure in the keg (actually if the pump is about a meter higher than the keg, the weight of beer in the pipe will prevent the beer forcing out of the pump; the keg's pressure is regulated that low!).

Spoon said:

Solutions:
1) Keg it, regulate it to 1-2psi, and CAMRA be damned with their <insistence> that no CO2 is used.

Click to expand...

That's the one! I don't think CAMRA activists give a fig about what we do in our homes!

peebee said:

Yikes! I've just noticed what you were proposing...

No, you can't attach the propane regulator to the CO2 bottle even after sorting out the dreaded "POL" coupler: The regulator will not handle the pressure of the CO2 bottle. It must have a "primary" set at about 1-4bar. I've attached an image from the rest of the article to dispel any confusion.

The hazards of posting an excerpt!

Click to expand...

O-k--a---y. So now an even dafter question ...


As an ex-sports diver my tank sat on my back at 200+ Bar but the on-demand regulator gave me just millibars above ambient pressure, be it on the surface or 30 metres down.

Surely there are applications for CO2 where the delivery pressure is in the mBar bracket; even if they need a two-stage regulator.

Dutto said:

O-k--a---y. So now an even dafter question ...

"Why do you need a Propane regulator?"​

...

Click to expand...

Well the regulator I linked cost about £12. Cheap and cheerful. Okay you still need £25 worth of welding regulator or the like to drop about 860PSI in the cylinder down to 15-60PSI (MAX 230PSI).

I guess "cheap and cheerful" doesn't cut the mustard for diving regulators! Unless you can tell me different... Or even point me at alternative regulators.

peebee said:

Well the regulator I linked cost about ��£12. Cheap and cheerful. Okay you still need ��£25 worth of welding regulator or the like to drop about 860PSI in the cylinder down to 15-60PSI (MAX 230PSI).

I guess "cheap and cheerful" doesn't cut the mustard for diving regulators! Unless you can tell me different... Or even point me at alternative regulators.

Click to expand...

There's this one ...

https://www.ryvalgas.co.uk/products/view/ryval-single-stage-two-gauge-co2-0-10-bar-regulator

... only a single stage but made specifically for the job and adjustable down to less than 1 Bar; maybe a possibility?

Just had an "Oh my God!" moment looking for my old diving regulator. The Snark II and III are both there - under "Vintage SCUBA Gear"!

I feel old and in need of a wee nip before I shuffle off to bed!

Dutto said:

There's this one ...

https://www.ryvalgas.co.uk/products/view/ryval-single-stage-two-gauge-co2-0-10-bar-regulator

... only a single stage but made specifically for the job and adjustable down to less than 1 Bar; maybe a possibility?

...

Click to expand...

Less than 1 bar? I'm after a lot less than 1 bar! Its a cylinder type regulator that'll never make it down to 100mbar or thereabouts; it'll stick! Would make a good (but expensive) "primary" though. For regulating such low pressures (at a reasonable price) you need a "diaphragm" type regulator: The ones that look like flying saucers, like your diving regulator.

That's the basis of my methodology! An "aspirator" ("breather") will maintain zero PSI (psig in case anyone picks me up on it). CO2 saturation in beer at zero PSI is a bit less than 1 volume (at room temp.) so anything over that that the beer contains it will give up to the atmosphere (via the breather, which doesn't allow pressure in the keg to increase). The result: I and many others, perceive the beer as "flat".

This is presumably why "breathers" don't extend the life of beer more than a few days.

Click to expand...

Are we talking 'life' until it goes flat, or life until it goes off due to oxidation or other contamination?

2nd hand information as I've never done it, but I'd heard of casks hooked upto aspirators and the beer lasting as long as you'd expect it to in a corny. That was with a cask tap, hence my comment about beer engines, again that was 2nd hand information based on what I'd read when building my kegerator. Decided against hand pumps for that reason as despite allowing for even lower pressures, there didn't seem to be a foolproof way to keep the beer in the keg fresh.

I guess any experimentation is difficult as the equilibrium takes a very long time to establish, days for beer in the cask to de-gas to the equivalent of 1-2psig, and days again to go 'flat'. Then you pour the beer, and it's exposed to <<1% CO2 in the atmosphere, and it's got some fizz for an hour (maybe 2).

Spoon said:

Are we talking 'life' until it goes flat, or life until it goes off due to oxidation or other contamination?

Click to expand...

"Flat". In 40 years of home brewing I was always disappointed not to be able to achieve "cask conditioned" style beer. You've just hit on the subject that was turning point for me and the reason for me writing this post and the article it relates to...

A "breather" keeps the beer surrounded in sterile CO2 so why is it accepted that they only keep the beer a few extra days? It's not going off (through contamination/oxidation). So it must be going flat? But it must still be saturated with CO2 because it is surrounded by CO2. So the beer still contains about 0.9 volumes of CO2. It isn't flat. Tastes flat to me, but others (as you've exampled) say its fine.

So I coined "perceived as flat" to deal with this.

Now I want to convince others! All those people who want to brew "cask conditioned" style beer but who stopped reading this thread ages ago because it is too "techie". So this gentle sparring with you, with others, and perhaps others to come, is helping me figure out how to reach those who have stopped reading this thread! After all, with you I must be close to "preaching to the converted"? But if so that's one down, many tens, or hundreds, to go!

Cheers! :thumb:

For the uninitiated, what is an aspirator (and don't say a French vacuum cleaner!), and how would one go about attaching one to a cask?

Steved53 said:

For the uninitiated, what is an aspirator (and don't say a French vacuum cleaner!), and how would one go about attaching one to a cask?

Click to expand...

Same as a "breather". Attaches to the "gas in" line. So when removing beer from a cask this creates a slight vacuum (oops, mustn't say "vacuum" - "a slight negative pressure"). The "breather" feels this and opens up the gas line to keep pressure steady. This means CO2 is going into the cask, not air, so the beer shouldn't go off.

But for many the beer will still become unpalatable after a few days which is what this thread is all about.

I'm arguing against using "breathers" ("aspirators") for home brew. Using an LPG regulator maintains a slight positive pressure in the cask which I argue keeps home brewed beer in a "cask conditioned" state for very much longer (sort of counter-intuitive). This is what that graph tries to illustrate.

Steved53 said:

For the uninitiated, what is an aspirator (and don't say a French vacuum cleaner!), and how would one go about attaching one to a cask?

Click to expand...

Sorry. I got corrected! There is a technical difference between "breather" and "aspirator" but no-one could tell me what it was! But they do the same job; maintain zero PSI by dribbling in a bit of CO2 (instead of air, and the hazards that brings).

I have just picked up this thread after waiting for someone who uses aspirators, or breathers to chime in. I was going to go down that route and wanted to see what other folks impressions were.

So they way I see it and after reading your thread, is that a low pressure regulator set @1-2 psi will be able to maintain the CO2 disolved in the beer by either natural carbonation, or by some level priming with small amounts of sugar?

As I have already bought a breather, I may aswell try it and then add a regulator if the carbonation is not to my liking.