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	FORUM ON BEER, HOMEBREWING, AND RELATED ISSUES
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Contents:
  How to throttle magnetic pump? ("Brendan Oldham")
  Re: beer wiki ("Greg 'groggy' Lehey")
  Re: Was RIMS Controller now is HBD Christmas Present ("Gary Smith")
  Re: Re: Beer in Nurnberg ("Greg 'groggy' Lehey")
  Leuven Pale Ale Yeast ("John D. Misrahi")
  RIMS Ramp Rates, PID Controlled etc (FRASERJ)
  RE:Transporting keg beer (Michael Hartsock)
   (Doug Mosher)
  trehalose pt 2, was Re: tackling oxygen [and more] (another follow up) ("-S")
  trehalose pt 1, was Re: tackling oxygen [and more] (another follow up) ("-S")
  Zymurgy Calendar/Kudos submissions & Updating the AHA Clubs database ("Kathryn Porter")
  1" SS coupling source (orourke mike)
  RE: Rogue Chocolate Stout ("Doug Hurst")
  PET bottle beer shelf life? (Budris)
  PID Control ("Mike Sharp")
  Oh, Yeah!?! (Apologies and Justifications) ("Eric R. Theiner")
  RIMS temperature control ("Todd M. Snyder")
  RE: food grade paint ("Brian Lundeen")
  Caramelization ("Ronald La Borde")


* * * * * * * * * * * * * * * * * * * * * * * * * * * * *
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Date: Sun, 14 Dec 2003 23:09:34 -0700
From: "Brendan Oldham" <brendan_oldham at hotmail.com>
Subject: How to throttle magnetic pump?

I've got a new magnetic pump (from morebeer.com) and was wondering if the
best way to throttle the flow is to (1) restrict flow output or (2) use a
dimmer switch to reduce power to motor. I understand that reducing motor
speed would also slow the cooling fan, but I guess I could cool externally.
Does outflow restriction have any negative impact on pump/motor? Thanks in
advance.


Return to table of contents


Date: Mon, 15 Dec 2003 17:15:14 +1030
From: "Greg 'groggy' Lehey" <grog at lemis.com>
Subject: Re: beer wiki

On Sunday, 14 December 2003 at 13:31:24 -0500, Alan McKay wrote:
> A fellow in Australia recently started a brewing wiki,
> but unfortunately I do not have the link at hand.
>
> Will try to dig it up.

I don't know if it's the same one, but you could take a look at
http://www.metrak.com/wiki/homebrew/

Greg
- --
Finger grog at lemis.com for PGP public key.
See complete headers for address and phone numbers.


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Date: Mon, 15 Dec 2003 00:52:24 -0600
From: "Gary Smith" <mandolinist at ameritech.net>
Subject: Re: Was RIMS Controller now is HBD Christmas Present



> 
> P.S.: A Christmas donation to the server fund would be a nice way to
> say thanks to the Janitors & all of us.
> 

I should clarify, my above comment was directed to all of us on HBD & at 
no one in particular. I just sent a donation via mail to the HBD (For some 
reason I had a hard time getting the money transfered via payPal... Go 
figure) & I was thinking it would be wonderful if we all sent something that 
way because the server ain't free & so I'm taking it on myself to offer this 
reminder to the clan.

(Sending via check or MO or cash for the brave soul gives more to HBD 
because there's no PayPal exchange fee)

I belong to many listservers due to my interests & this is the only one that 
means enough to me to donate. Perhaps it's that for you too? 

Anyway, my 2 cents on what I think is a right good idea.

:)

Cheers all,

Gary

Gary Smith
CQ DX de KA1J
http://musician.dyndns.org
http://musician.dyndns.org/homebrew.html

If you pick up a starving dog and make him prosperous, he will not 
bite you. This is the principal difference between a dog and a man.

 - Mark Twain -




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Date: Mon, 15 Dec 2003 17:33:00 +1030
From: "Greg 'groggy' Lehey" <grog at lemis.com>
Subject: Re: Re: Beer in Nurnberg

*sigh* The mailing list software rejected my original post because it
contained real place names.  Here's the expurgated version.  In
general, but not always, replace "ae" by an a with two dots on top
(Umlaut) and ue by a u with an Umlaut.

Greg

- ----- Forwarded message from Greg 'groggy' Lehey <grog at auug.org.au> -----

> Date: Mon, 15 Dec 2003 17:11:59 +1030
> From: Greg 'groggy' Lehey <grog at auug.org.au>
> To: Stan Burnett <stanb at xmission.com>
> Cc: homebrew at hbd.org
> Subject: Re: Beer in Nurnberg
>
> On Saturday, 13 December 2003 at  2:33:11 -0700, Stan Burnett wrote:
>>
>> I have very limited internet access right now, so I haven't been able to
>> check the archives. Sorry.
>>
>> Soon I'll be driving from Prague to Nurnberg (spending a couple of nights)
>> and then to Freiburg (extreme western Germany, very close to French
>> border)--I'm picking up my nephew who lives with his mother in Freiburg
>> and bringing him back to Tabor for the holidays with his father.
>>
>> Any recommendations for beer drinking along this route?
>
> Nope, there's not much beer round there.
>
> Seriously: on the road from Praha to Nuernberg there's this place
> called Plzen where I'm told they make a reasonable beer.  Nuernberg
> itself is pretty good, too.  From there you have a number of ways to
> get to Freiburg.  (I assume from your description that you're talking
> about Freiburg im Breisgau; there are many Freiburgs in Germany).
>
> Assuming you're staying on the freeways (not necessarily a good idea),
> the most direct way is via Heilbronn and then either Stuttgart or
> Heidelberg to Karlsruhe and on to Freiburg.  You might like to see
> Heidelberg, but it's not much of a beer town.  You could also go off
> the freeway to Rothenburg ob der Tauber, which is a nice place to
> visit, but not specifically related to beer.
>
> Alternatively, you could go South to Muenchen (Munich), driving through
> the Hallertau in the process (about 50 km north of Muenchen).  It's a
> bit further to go, but if you're looking for beer, and you haven't
> been there before, you'd kick yourself if you missed it.
> Unfortunately, you'll miss one of the nicest parts of drinking in
> Muenchen: the beer gardens.  They're only open in summer.  From there
> you could continue to Tettnang on the North side of the Bodensee (Lake
> Constance), not omitting Neuschwanstein Castle near Fuessen, and then
> on to Freiburg through the Black Forest.  A lot depends on the weather
> at this time of year, of course.
>
> Freiburg itself (and the area) is more wine than beer.  The beer's not
> bad either, but it certainly doesn't have the ring that Plzen or
> Muenchen have.
>
> I don't have any specific places to recommend in Plzen or Muenchen.
> I've never been to Plzen, and in Muenchen I find the quality of the
> pubs is pretty uniform.  I don't know any microbreweries, for
> example.  But you could visit the Hofbraeuhaus for breakfast (yes, they
> drink beer for breakfast in Bavaria) and get away from the stereotyped
> tourist trap that it has otherwise become.

- ----- End forwarded message -----

- --
Finger grog at lemis.com for PGP public key.
See complete headers for address and phone numbers.


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Date: Mon, 15 Dec 2003 08:04:30 -0800
From: "John D. Misrahi" <lmoukhin at sprint.ca>
Subject: Leuven Pale Ale Yeast

Has anyone used this Wyeast offering? i think it's on their 'seasonal' list
(I have been able to order them year round unlike White Labs 'seasonals). I
am consideing ordering a packet (Trying out some of the yeasts no one seems
to get around using - at least no one around here). I was really happy with
the Wyeast Saison..

Any comments on the Leuven yeast?

What would it be ideally suited for?

john




Return to table of contents


Date: Mon, 15 Dec 2003 08:11:49 -0500
From: FRASERJ at Nationwide.com
Subject: RIMS Ramp Rates, PID Controlled etc





Ramp rates seem to be of concern in all the discussions recently over PID
controllers etc.  I "somewhat" overcame the ramp rate concern by using TWO
low density heater elements, connected in series and run at 220 Volts
across the ends of the serially connected elements.  The result was a ramp
rate on 1.7 degrees/minute, with no caramelization(.sp?) at all.

And Todd, I use a Visual Basic program and digital temperature sensors to
control my setup and I still got a pretty nasty (2-4 degrees) overshoot on
grainbed temperatures, which I have tracked down simply to the thermal
momentum setup in the RIMS Chamber itself!  I am guessing a PID Controller
would throttle my system using power control (cutting back on wattage)
better than my hard ON/OFF control of the elements would.  The discussion
on enzymes and location of the probe makes me think I need to relocate the
probe in the RIMS Outlet like I originally had it, but from memory I had
attenuation problems.  Leads me to believe the each individuals RIMS
brewery needs to be tuned according its construction!

I partially overcame the problem by adding an extra step in my ramps and it
works pretty well.

John M. Fraser
rims-brewing.tripod.com



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Date: Mon, 15 Dec 2003 06:53:47 -0800 (PST)
From: Michael Hartsock <xd_haze at yahoo.com>
Subject: RE:Transporting keg beer

I agree with jeff about 2L bottles (I also use 3L
bottles).  However, I have a cheaper alternative to
the carbonator cap.  For $2 a piece I got chrome clamp
in tire valves.  I put an air chuck on a valve off my
co2 dist. manifold and drilled an appropriate hole in
the cap for the 2L bottle.  YEAH! $2 carbonator cap
instead of 12.  At that price I can afford to loose
them.  And I also have the luxury of using smaller or
larger bottles as appropriate.

Secondly I just made a very inexpensive cp bottle
filler.    I used a out dip tube off of a ruined
corney keg and a few lengths of matching OD CPVC
potable water tubing and a T compression fitting.  Two
cobra faucets make for easy to use gas in and liquid
in valves and they fit snuggly over the tubing.  Cheap
CP bottle filler used in conjunction with cheap
carbonator cap and your solution for transporting keg
beer is at hand!

If you're worried about presentation, don't be.  You
can either pour it in to a pitcher or if your beer is
good... the presentation won't matter.

mike
Columbia, MO

=====
"May those who love us, love us.
And those that don't love us,
May God turn their hearts.
And if he doesn't turn their hearts,
may he turn their ankles
So we'll know them
by their limping."



Return to table of contents


Date: Mon, 15 Dec 2003 09:35:43 -0700
From: Doug Mosher <dhmosher at juno.com>
Subject: 

Hello Stan, I was stationed in Fuerth from 1978-1980 and was
recently in Nurnburg last year for a few days.

A list of the Nurnburg pubs can be found at

http://www.xs4all.nl/~patto1ro/nurnpubs.htm

with a more extensive Euro list to be found at

http://www.xs4all.nl/~patto1ro/

I've always had a fondness for Nurnburg and the old city, with it's
many pubs (most of which have changed since I remember them)

Some recommendations I would make is to  try the Nurnburg brats and
sauerkraut which are unique to the city and also Lamms Brau heffe weiss.
On the list I noticed Schlenkerla-Schranke which serves the famous Bamburg
smoked beer.

hope you enjoy your stay

Doug Mosher


 >Date: Sat, 13 Dec 2003 02:33:11 -0700
 >From: Stan Burnett <stanb at xmission.com>
 >Subject: Beer in Nurnberg


 >I have very limited internet access right now, so I haven't been able to
 >check the archives. Sorry.

 >Soon I'll be driving from Prague to Nurnberg (spending a couple of nights)
 >and then to Freiburg (extreme western Germany, very close to French
 >border)--I'm picking up my nephew who lives with his mother in Freiburg
 >and bringing him back to Tabor for the holidays with his father.

 >Any recommendations for beer drinking along this route?

 >Thanks!

 >Stan Burnett
 >Tabor, CZ



Return to table of contents


Date: Mon, 15 Dec 2003 11:30:47 -0500
From: "-S" <-s at adelphia.net>
Subject: trehalose pt 2, was Re: tackling oxygen [and more] (another follow up)

> Are you suggesting that the intrinsic lag is insignificant compared to the
> apparent or saturation lag?

We could estimate it easily enough.

1L of CO2 at STP weighs 44/22.4 or just under 2 grams.  So 2gm/L is about 1
volume of CO2, the level at which some bubbling will begin.  Producing this
requires fermentation of very nearly 4gm of sugar per liter or the
fermentation of about 0.4P of wort sugars.

I've reviewed some time vs SG data from the texts and it seems that the last
50 hours of log-phase growth of a good 12P brewery fermentation causes the
loss of about 25SG degrees of *apparent* gravity.  That's about 0.5
*apparent*SG degree per hour.  The *real* attenuation rate is about 81% of
that using the standard estimate.   So a good late rate of fermentation is
*roughly*  0.4SG real degree per hour or 0.1P per hour.

We would expect that with less yeast present at the beginning that the
"brewery lag" , the time from pitching until first CO2 bubbles, will be
considerably longer than [0.4P/(0.1P/hr)] 4 hours.  It seems entirely
reasonable that the 8 to 24 hour sort of lag times reported is almost
entirely time spent saturating the wort with CO2, and relatively little time
spent transitioning from dormant to growth phase.

> The idea to model lag (transition from dormant state to active state) is
to
> consider
>
> - depletion of glycogen, to power sterol synthesis
> - sterol synthesis utilizing oxygen & carbohydrates(glycogen or external
> sugars- whichever is quickest/available)

Given little or no nutrients, but plenty of oxygen dormant anaerobic healthy
yeast will deplete their glycogen in a hurry - several hours, and sterol
levels also rise very quickly under this condition - 3 hrs (see "Brewery
Yeast Fermentation Performance", K.Smart, 2000, K.Smart, pp140-151)  while
the squalene is minimized in abt 2 hrs.

In more conventional once aerated brewery fermentation glycogen is used
almost as quickly, a few hours.  The sterol levels continue to rise for
about the first 15-20 hours of a normal fermentation.  Apparently the first
step in the squalene-> squalene-epoxide process uses oxygen & glycogen is
relatively quick, compared to later steps which create lanosterol and then
other sterols from the epoxy-squalene.

In a stirred study of the first 12hrs of fermentation there was virtually no
cell budding to 2 hours, then the rate of budding rose to a peak by about 6
hours (~90% of the population budding).  Total cell count didn't increase
much till the 6hr mark.   Quain& Boulton call the transition from G0
(stationary) to G1(growth phase at 2 hours and state this is fueled by
glycogen breakdown.

> - utilization of external sugars (function of membrane quality)
> - building membrane quality (function of levels of sterols, UFAs)
> - transition from dormant to active, correlated to membrane quality
> - UFA synthesis

Very complex topic with some contradictory results in the lit.

> I was thinking that building that building the membrane requires a
certains
> amount of carbohydrates, and if the glycogens aren't enough, utilization
of
> externals are the only option. This could explain the slow start. The idea
> is that the rate of cells entering the active state is proportional to the

I'd think that the growth of new cell walls rather than membranes would be a
much bigger destination for wort carbons.  Still vast amounts of energy
(from fermentation) are needed to fuel the very expensive lipid
construction.  As you say, if internal glycogen reserves are inadequate, as
in unhealthy yeast stored too long,  then growth would stall after internal
reserves were used up.  External glucose would probably be the next energy
source brought online, but the impact on growth and lipid formation will be
quite complex.

There is a JIB paper by Quain et al (sorry it's not handy) in which they
study the glycogen sterol rates explicitly.  The glycogen drops hard early
in fermentation but only slowly rebuilds to pre-pitching levels over many
hours (perhaps 100 hours) in the fermenter.   Much of the total glycogen is
rebuilt very late in fermentation, just like trehalose.  From this I'd
assume that if there is insufficient  glycogen to form lipids early on -
that lipid growth would be stalled until both glycogen and oxygen were
available - significantly later and maybe never.   This could explain some
"stuck" fermentations.

> Referring to you mentioning poking holes in the idea, can you see a major
> flaw in this idea? If so where?

You seem to be on the right track, but you should probably review
Boulton&Quain, "Brewery Yeast & Fermentation" for a modern viewpoint and
references.

> Any idea where trehalose would enter here? that's one of the missing
pieces
> it seems.

Forms largely in response to stress.  Helps preserve yeast throughout many
forms of cell stress.  Forms late in the normal brewery fermentation with
detectable increased uptake of wort sugars.  Forms earlier and in greater
quantity w/ higher gravity.  Can be formed from glycogen in the precence of
stress when other carbohydrates are absent.  It's rapidly dissimilated at
the beginning of fermentation - first 10 hours very roughly.  I *expect*
that the protein preserving properties of trehalose will also interfere with
enzyme activity.  If that is so then it makes sense that trehalose is
destroyed as the cell comes out of dormancy, and created just before
dormancy and immediately in stress conditions.

 -Steve




Return to table of contents


Date: Mon, 15 Dec 2003 11:29:27 -0500
From: "-S" <-s at adelphia.net>
Subject: trehalose pt 1, was Re: tackling oxygen [and more] (another follow up)

Fredrick asks ...

> Hmmm interesting. I don't understand trehalose yet. So would act like
> emergency stock of spare carbon? for repairs of stress damage? or does it
> work any other way?

Trehalose is a non-reducing disaccharide.  It's a bit like sucrose, but with
two glucose molecules rather than a glucose+fructose.  The two number-1
carbon molecules (the reducing ends) are coupled in an alpha configuration.
It's been classified as GRAS (generally recognized as safe), has a sweetness
about half that of sucrose and Cargill recently started vending it under the
trade name 'Ascend' for use in some mass market foods as a
sweetener+stabilizer.  That's good news for us yeast farmers since it can be
used as a stabilizing additive when storing yeast at ~10P.  I don't know the
price but when I looked for trehalose a few years ago it was far too
expensive
for HB use.

Trehalose has a role in stabilizing proteins from desiccation and cold
damage and probably other stresses.   A lot of micro-organisms make
trehalose in response to stress.  Some Macro-organisms like shrimp and
lobster do too and that probably impacts the flavor.  It's also been shown
to have a role in stabilizing lipid membranes aside from the protein
stabilization.   That is trehalose protects the lipid membranes during phase
transitions to freezing & back.  To do this both sides of the membrane must
have access to trehalose, so yeast will release some trehalose into the
space
between the exterior membranes and cell wall.  They have a specific enzyme
to permit this transfer out.  The presence of glucose represses this
transfer
of trehalose to the membrane.  Actually glucose causes all sorts of odd
changes aside from Crabtree effect.

Yeast produce significant amounts of  trehalose when subjected to various
stresses.  Brief heating of yeast causes them to accumulate trehalose and
they are subsequently more heat resistant, for example.  For yeast at least
trehalose protects against heat as well as cold.  Alcohol and high osmotic
pressure (from things like hi-gravity and sorbates) cause yeast to
accumulate trehalose.   Yeast accumulate trehalose in "nutrient deficient"
conditions as well ... the same conditions that generally cause
flocculation, but this is somewhat after glycogen is created.  The trehalose
levels rise if glycogen rich dormant yeast are exposed to lots of oxygen (a
stressor).  They actually use glycogen to form trehalose in this case.
Quain mentions unpublished data which supports the idea that there is a
elevation in sugar uptake late in brewery fermentation which corresponds
with trehalose creation.

Growing brewing yeast in low stress conditions, fermented in 10-11P wort,
they may accumulate 2-5% trehalose by weight.  In tests with very high
gravity wort, brewery yeast accumulate up to 25% trehalose by weight - even
when the alcohol is removed by dialysis !    For dried baking yeast(also
S.cerevisiae) 10% trehalose by weight is considered minimal for the drying
process, while 15-20% is preferred.


> I thought it would generate ATP as well though possible less than
glycogen?

I don't want to overstate the case.  Yeast can metabolize the glucose units
in trehalose, but they expend energy in constructing it, and also in
degrading
it with trehalase enzyme.  They go to the trouble of  forming trehalose for
"reasons" other than energy storage.  Glycogen is far better for that..

> Isn't the biologists definition of the lag time for a cell as the time
from
> pitching to the time the cell is active, and a budding cycle is initiated?

I was talking about the brewing lag time ... the time from pitching till
evidence of fermentation is clear ... generally till CO2 evolution is
obvious.

> I like to make a distinction between the apparent lag (first appearance of
> CO2 in airlock) and the intrinsic lag, and CO2 production from the yeast.
So
> far I haven't done very much tests to have a clear opinion what can be
> attributed to saturation times and what are really intrinsic lags. So I am
> attempting to account for variations in both. The saturation lag should be
> straightforward to model once you know the production rate, so I am
> currently trying to focus on understanding the intrinsic lag.

That's a different thing of course.  Initially on pitching stationary phase
anaerobic yeast into aerated wort they will consume glycogen stores and
ignore wort sugars.  They *may* excrete amino acids as a shock reaction.
It's a while before they start consuming wort glucose.   I'm certain you can
find papers that describe how this impacts the cell division cycle.   Look
for synchronized cultures as a topic.

 -S (more to follow)




Return to table of contents


Date: Mon, 15 Dec 2003 10:08:23 -0700
From: "Kathryn Porter" <Kathryn at aob.org>
Subject: Zymurgy Calendar/Kudos submissions & Updating the AHA Clubs database

Hello Homebrewers,
Due to the Holiday season the deadline for the March/April Zymurgy 
Calendar and Kudos submissions has been moved forward on the 
schedule. Please have all competitions/events and organizer's reports 
submitted by December 19, 2003 to ensure they are printed. In case you 
didn't know, you may now submit calendar events online: 
http://www.beertown.org/homebrewing/hb_calendar.html  
Please send hard copies to: Kate Porter ~ Events, Association of Brewers, 
736 Pearl St, Boulder, CO 80302.

Also, we need your help to keep our online club locator up-to-date. Please 
check out your club's listing on http://www.beertown.org, just select 
Homebrew Clubs from the Locator drop down box on the right side of 
http://www.beertown.org pages. Homebrew clubs are listed by state and 
arranged alphabetically by city. If your club is not listed use the online
form 
to add it (Note: many club records were eliminated when the new locator went 
up a few months ago in our effort to clean out old information). You can also

make corrections to listed clubs, via the online form. Furthermore, If you
find 
clubs that you know have gone out of existence, please use the update form to
delete them from our records. *Please note*, updates are not automatic, so be

sure to allow a few days for us to update our records.

Thanks for your help!

Kate
___________
Kathryn Porter
Association of Brewers
www.beertown.org



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Date: Mon, 15 Dec 2003 09:21:40 -0800 (PST)
From: orourke mike <dert12345 at yahoo.com>
Subject: 1" SS coupling source

Anyone know of a place to mail order 1" straight
(merchant) threaded stainless couplings for water
heater type elements?




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Date: Mon, 15 Dec 2003 12:06:13 -0600
From: "Doug Hurst" <dougbeer2000 at hotmail.com>
Subject: RE: Rogue Chocolate Stout

Mark Arneson is looking for a Rogue Chocolate Stout recipe.  I've been 
wanting to brew this one for a while.  One thing I like about Rogue is how 
much information they're willing to put right on the label:

Harrignton and Klages malt
Crystal 135-165
Beeston Chocolate Malt
Rolled Oats
Roasted Barley
Natural Chocolate Flavoring
Cascade Hops
15 Plato  (~1.061 SG)
69 IBU

Harrington and Klages are barley varieties which may be difficult to obtain 
but any American 2-row malt would be virtually the same.  The only 
ingredient I'm really unsure about is Natural Chocolate Flavoring.  Perhaps 
start with a very small amout of bakers chocolate and move up from there.  
I'm sure someone else has experimented with chocolate and would be willing 
to share.

Here's the recipe I would estimate from the above:

8-9 lbs 2-Row (depending on system efficiency)
 .5 - .75 lb Crystal Malt (135-165L)
 .75 - 1 lb British Chocolate Malt
1 lb Rolled Oats
 .75 - 1 lb Roasted Barley
Maybe .25 oz. Baking Chocolate (not sure)

~2 oz. Cascade 60min (assuming 6%AA)
~1.5 - 2 oz. Cascade 30min
~1oz. Cascade 5min

This beer needs a lot of body and sweetness which indicates a single 
infusion mash at 155-158F for 60 minutes.

If you make this let us know how it turns out.



Doug Hurst
Chicago, IL
[197.5, 264.8] Apparent Rennerian



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Date: Mon, 15 Dec 2003 13:16:20 -0500
From: Budris <budris at optonline.net>
Subject: PET bottle beer shelf life?

Does anyone know how long will beer stay "fresh" when stored in the 6-liter
PET bottles that come with the Tap-A-Draft system?
I'm trying to find out how long the beer will last in the PET bottles before
there is a noticeable loss of flavor due to oxidation.
I have been doing some research on the internet and see that PET makes a
very poor oxygen barrier.  Oxygen gets to the beer even when the beer inside
of the PET bottle is under pressure (carbonated).
I saw that a company called PPG industries has come up with a spray-on
coating that extends the shelf life of beer stored in PET bottles by several
months.
Are there any companies out there selling 6-liter PET bottles with this
oxygen barrier coating?

 -Brian Budris




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Date: Mon, 15 Dec 2003 10:55:14 -0800
From: "Mike Sharp" <rdcpro at hotmail.com>
Subject: PID Control

Todd comments on PID Temperature Control

"The problem I see with PID control is not accuracy.  Given enough time, a
PID will force the temperature to the set point very accurately.   It will
just take a _long_time_.  That's my problem with it."

I know this always starts a whirlwind of postings, but I can't resist
jumping in.  There are so many mis-conceptions about PID control.

The maximum ramping rate has nothing whatsoever to do with the type of
control--it's the amount of power you apply to the heating chamber.  The
only thing that PID control does is permit the greatest possible ramping
rate without overshoot.  It's not a question of accuracy at all, but a
question of getting to setpoint without overshoot and at a pre-determined
rate.


Todd:
"To avoid a large overshoot when there is a delay between the heat addition
and the temperature rise, the temperature ramping rate has to be small.  A
typical heating rate is 1 degrees F per minute.  So a 122F to 148F ramp
would take 26 minutes"

No, you're referring to problems with what's called "bang-bang" (technical
term) or simple on/off control, which will overshoot badly if the heating
rate is high.  If you're measuring the temperature at the exit of the
heating chamber, the time delay is minor.  I say if you use any sort of
manual control, and adjust the heating rate yourself, you're doing exactly
what a PID does in the first place: Applying lots of heat at first, and less
as you get close.

PID has three methods of control.  

1. Proportional control, which applies more power the farther you are below
setpoint, 

2. Derivative control, which is what prevents overshoot (the faster the temp
is rising close to setpoint, the greater the Derivative term (which tends to
slow things down).  

3. Finally, there's integral control, which is what gets the control the
last few degrees to setpoint.  Some controllers have an anti-reset windup
setting that allows you to essentially "disable" the integral term when
you're a long ways from setpoint.  This prevents overshoot by keeping the
controller from trying too hard.  It's especially useful in power limited
systems, because the controller tries so hard to get temp up, the Integral
term can get way off.  Once the temp gets close, the integral term can't
back down fast enough to prevent overshoot.  

In a PID system, you first set the proportional band to a range of
temperatures.  Let say you're trying for 148 F setpoint.  Your proportional
band (which depends on the system physics) might be set to 10 degrees, from
138 to 148.  At the instant the controller is set to 148 from your 122 rest,
the wild (or process) variable is 122, temperature is not changing, and
you're below the proportional band.  The controller begins applying full
power (well, whatever you've set to be full power, which may in fact be a
lot less than 100%), and temperature begins rising at the maximum rate your
system can sustain.  

As temperature rises, the differential term might start cutting things back,
especially as you approach setpoint.  It's only goal is to prevent overshoot
in a system that's tuned to reach setpoint as fast as possible.  But before
that happens, your temperature crosses 138 F, and as the system enters it's
proportional band, power starts decreasing.  If things were strictly
proportional, at 148 F the power would be completely off.  So the
temperature would actually stabilize somewhere between 138 and 148,
depending on the heat losses of the system.    

However, we have a PID system, so now that we're above the temp where the
anti-reset windup setpoint is, the integral term begins increasing power to
get the temp to setpoint.  It works agains the differential term to achieve
setpoint.

In a properly tuned system (and assuming you can apply as much power as you
want), the temperature will reach a stable setpoint without overshoot faster
using PID than any other method.  

By the way, asymptotic approaches to a setpoint are probably going to be
much faster than linear approaches to a setpoint.  

Now, lest I be flamed by those who feel that throwing hot rocks into their
mash is all the heating control a brew needs, not all systems really need
PID control.  It depends on the local system dynamics, the degree to which
you need to control ramping rates, and how close to setpoint you really need
to be.  I've installed PID systems where the Integral and Differential terms
were zero, meaning I had strictly proportional control.  This is very useful
in some cases, such as controlling pump speed to maintain level in a tank in
some sort of continuous process.  There, the goal is not to maintain a set
tank level, but to keep the tank level low at full flow, and high during low
flow, to be able to handle surges.  

Most grants are pretty small, and a simple float switch is enough, but I've
built systems where the flow rates are high enough where the grant level
must be electronically controlled.  An example was a bottling line that used
a surge tank pressurized with nitrogen to push the wine into the bottles at
high speeds.  The waukesha pump was controlled on a VFD to maintain tank
level no matter how fast the line was operating.  Not a PID situation, but
definitely a "P" situation.

Regards,
Mike Sharp


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Date: Mon, 15 Dec 2003 13:44:42 -0500
From: "Eric R. Theiner" <rickdude02 at earthlink.net>
Subject: Oh, Yeah!?! (Apologies and Justifications)

I have this sinking feeling that I have guilted a few people into 
supporting one of my products by
posting a whiny note.  I am sorry for that, although I am still grateful to 
Steve and Kenneth by
posting their support publicly, as well as a few other guys for their 
private notes.

Okay-- here's Point 1:  I post about cleaners because that's what I 
know.  I happen to make
some, and, of course, I think they're great.  It would make no sense it I 
didn't say this.  I don't
post about PID controllers because I have a very limited understanding of 
them (Dr. Ray, my
Controls professor would have a cow if he read that).  Same with any number 
of other subjects.
And I don't want to fill up the HBD with "me too" posts for things that are 
reasonably well covered,
either.

As for the concern that I'm getting rich off the back of the HBD server, 
rest assured that it is not
happening.  I still work a day job, and probably will for the rest of my 
life.  My business pays for
homebrewing, a few toys (digital camera, kayak, etc.) and that's about 
it.  If it made enough,
you guys would see me at the conferences and such, but it doesn't.  And the 
reason is most
likely that I'm a really crappy businessman.

But Brian Lundeen has a good point.  So here's my Point 2:  I *am* getting 
advertising out of
this.  In fact, the sample requests have gone through the roof since I last 
acted like a whiny
little kid.  And I do sponsor just about anyone who asks (usually by 
sending free product, but
that's not practical in this case), so it's really not about me being a 
greedy bastard-- it's about
me being a slug by not paying attention to my surroundings.  So my next 
email will be to Karl
& Pat to discuss this.  And maybe a few of you non-business owners might 
think about doing
it, too.  This is a great resource whether you've got something to sell or 
not and we should
keep it going.

Rick Theiner
LOGIC, Inc.
www.ecologiccleansers.com




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Date: Mon, 15 Dec 2003 14:16:21 -0500
From: "Todd M. Snyder" <tmsnyder at buffalo.edu>
Subject: RIMS temperature control

Hi All,

Thanks for all the posts about RIMS temperature control.  A couple of
discrepancies between my concept of RIMS setups and information in the posts
have become apparent.

I assumed that the pumping rate thru the heat chamber was fairly slow, 1 gpm
or less.  But 5gpm was referenced by Dion as his SOP.   How does this
compare to other RIMS?  A fast recirculation rate and a probe placement on
the outlet of the heating chamber would allow the target temp to be reached
quickly without ever overheating the wort.

Assuming a simple mixed reactor, 5 gallons of wort, and 5gpm flowrate, and
wort exiting the heating chamber at the target temperature, after 1 minute
the temperature would be 63% to the target [ (Target -
Temperature)/(Target - Initial) = 0.37 ] , 2 minutes would be 86%, 5 minutes
99%, and after 10 residence times (10 minutes) it would be 99.995% on target
compared to its initial temperature.

But 5 gpm seems really really high to me.  How can you get that much flow
thru the grainbed without compressing it?  What flowrate do other RIMSers
use?

Gary says that the flow is higher than 0.25-0.5 gpm, but gives no number for
what he uses, can you post your RIMS flowrate, Gary?  I also agree with Gary
about the carmelization myth.  After making maple syrup with my family for
15+ years, I can say that a dilute sugar solution like wort will not scorch
no matter what the watt density (within sane reason, maybe not 10^6
watt/sqin).  The heat transfer to a maple syrup finishing pan is similar to
homebrewing kettle set at a very high boil, and it won't scorch unless taken
_way_ past syrup which is 66 (?) brix.  (or is that honey?)  Anyway, the
point is that as long as there's some water in there, it won't scorch.  And
wort is very dilute compared to syrup so it should never be a problem unless
the mash sticks.

I have, however,  witnessed a white slimy protein(?) layer build up on a
recirculated wort heating element which scorches if not cleaned off between
batches.

Dion evokes the spirit of George Fix, seems to take offense at my comments,
and points out that the enzymatic activity is in the wort solution, not in
the solid portion of the mash.  I agree, and it's another reason to put the
temp sensor on the outlet of the heating chamber to avoid overheating and
denaturing the enzymes.

Dion, I didn't mean to say that saccharification begins at 122. I was just
using that as an initial temp to start a ramp as a demonstration, I know
that other enzymes, mostly proteinases, are at work down there in that
range.  But you did post your ramp rate, thanks.  You use 1.5F/min.  So to
go from 122 to 154 took 48 minutes.  Then you hold it at 154 for 60 minutes.
I agree that the 15 minute conversion idea has problems, but I never brought
that subject up.

So, Dion,  you are happy that the ramp time is almost as long as the
saccharification rest?  I'm not trying to be sarchastic or anything.  It
just seems strange to me.

<A properly designed RIMS system will a) not scorch wort and b) will>
<allow you to manipulate rest temperatures and achieve EXACTLY the>
<result you want.  If a particular system will not work this way, then>
<it was poorly designed.  There is nothing wrong with the basic RIMS>
<principles, only in some individual's poor implementation.>

Ok, so a 1.5F/min ramp rate resulting in a 48 minute ramp is the result of a
well designed system?  If you say so...... (ok, now I am trying to be
sarchastic :-)   I can't help it when someone gets so defensive.)  And sure,
it'll achieve EXACTLY the target temp, I agree, but it will take TIME.

Can you answer this:  If the point of the step mash is to go from one temp
to another, why do it at only 1.5F/minute? What factors resulted in that
value?   I mean, the goal is not to traverse thru those in-between
temperatures at 1.5F/min, right?  You're original goal was to go from one
temp to another, to another.  You've shown us, very well I might add, with
actual test batches that it isn't detrimental to the wort to proceed at
1.5F/min, but why go so slow?

If the wort can be pumped at 5gpm (and scorching is not a problem so all the
heat can be poured on) and the wort exiting the heater can be raised to the
target temp by the PID (a perfect application for it, no time lag, no
overshoot), that would lead to a ramp time of more like 3-5 minutes to be
essentially on target throughout the mash, not 48 minutes.

So what gives?  Is the flowrate actually much less than 5 gpm?

Martin, what flowrates were you using for your model?  The model you
describe sounds awesome, I'd love to see it in BYO or Zymurgy. It also makes
a lot of sense, you write:

"The model showed that the speed of temperature steps is predominately
contingent upon the wort flowrate, the temperature difference of the step,
and the depth of the grainbed."

This jibes with my incredibly simplified model up above, a mixed reactor
containing no solids.  It's just a 1st order model, but it says as yours
does that:

"My model indicates that the wort
will have passed through the heater at least three times before a majority
of the bed is near the target temperature,"

Three residence times would get the temperature 95% to the target, ie a 32F
step (122 to 154) would be at 152F after three times thru the bed, close
enough to be considered on target.

" If the thermocouple is located anywhere else in the
system, the PID control is fairly useless.  The thermocouple should be
located close to the thing (heater) its trying to control!"

That's exactly my point.  But the question is, what's a typical flowrate
thru the mash? It should be as high as possible without sticking the mash.
It seems like the 1.5F/min ramps other people see is the result of flowrates
~0.3 gal/min.  (5 gpm * 3 min/48 min).  Unless someone is able to pump a
high flowrate, the long ramp times are inevitable it seems.

Ken Meyer recommends using hot water additions for a step mash in
combination with a PID heated recirc loop to maintain the temp.  That's a
great idea too.  I mean, if you're there pushing buttons on the PID you
might as well just add boiling water and stir it in.  Good point, Ken,
thanks.

Todd Snyder
Buffalo, NY



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Date: Mon, 15 Dec 2003 14:09:23 -0600
From: "Brian Lundeen" <BLundeen at rrc.mb.ca>
Subject: RE: food grade paint


> Date: Fri, 12 Dec 2003 23:08:33 -0800
> From: "Jim Hinken" <jim.hinken at verizon.net>
> Subject: paint
> 
> Presque Isle Wine cellars sells a food grade paint for 
> presses, etc.  It should work well
> 
> http://shop.piwine.com/shopsite/prwc/product508.html
> 5964 Gondola Enamel, 500 cc

I have used this product on my grape press and its not bad. Gets a
little beat up where stems are rubbing against it. It would likely
suffice for the OP's purposes, with one caveat: he should check with
Presque Isle on the temperature restrictions for this product. It might
not be intended for use in boiling conditions and its food grade status
might not apply there. Better safe than sorry, I always say (which of
course, I don't actually always say, cause that would just make me seem
kind of weird).

Cheers
Brian, in Winnipeg


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Date: Mon, 15 Dec 2003 14:31:17 -0600
From: "Ronald La Borde" <pivoron at cox.net>
Subject: Caramelization

Todd M. Snyder asks several questions.

>I used to
>use a regular high density element, 1440 watts, 120 V, for an
archimedes
>rims system I was playing with and I never saw carmelization.  What I
did
>see was a white slimy protein? layer which, if not cleaned off
between
>batches, burned onto the element but did not impart any flavor that I
could
>percieve.  Has that been your experience too?

That white stuff, pretty as it is, is not,  I think, protein.

Normally I use the water from the tap filtered for chlorine removal.
After brewing there may be a slight grey or brown coating on the
element. This is in no way scorching, but some kind of protein
buildup.  I have used the element several times without cleaning it
with no problem.

But, once I used some bottled water that I had never used before, and
after only one brew, I had a fairly thick beautiful white coating on
the element. I did not remove it and during the next brew, the element
MELTED. Yes, I had to run to the hardware store and get another one,
remove and store the brew, then replace the kettle element to
continue.

I never used that water again, and never had that white coating again.
This is why I think it is not protein, but some salt impurity in that
water that caked on it.

I now clean the element with a plastic scrubby and some Barkeepers
Friend after every brew, it comes off easy and is never a problem.

As far as scorching, never happens. I brewed light wheat beers,
Pilsners, etc with no scorching.

By the way, it seems that RIMS people have found a nicer word for
scorching - it's now called 'caramelization'.

73's
Ron
=====
Ronald J. La Borde -- Metairie, LA
New Orleans is the suburb of Metairie, LA
www.hbd.org/rlaborde





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---