Calibration

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MHB

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Calibration
This is a warning
As a retailer we dont just sell stuff; we get to hear everyones problems and try to fix them.
There have been lots of guys coming in with beers they arent happy with; the cause of the problems has been errors in the mashing temperature. With more and more people relying on the (what really are very inexpensive) Dial Thermometers or Thermostats that have come into the market in the last couple of years, there has been a huge increase in problems associated with this type of equipment. When you think high quality dial and electronic equivalents cost 10 or more times as much, its no big surprise. Im not saying not to use the cost effective units, I use them myself, just be careful.

Calibrating your equipment is vital, get 1 good old fashioned glass laboratory thermometer that you can trust and use it to check your other equipment.
MHB
 
This post sounds like the result of one dim witted customer who didnt want to believe it.

Either way MHB, very true. I'd trust an electronic or old school glass thermo over a dial anyday of the week.
 
I wish to God it was one dim-witted customer it isnt.
Im highlighting a trend, this has happened often enough for me to think it merits posting. Some of the people who have had problems are skilled highly respected brewers, they just werent aware that both Dial and Electronic equipment needs calibrating. They are good enough brewers to know they had a problem and to come looking for a solution.
A very good glass/alcohol thermometer will set you back $10-15 (not talking Chinese shit ones, good ones) Calibrate your equipment; you get better beer and better efficiency.
MHB
 
Even the proper lab thermometers can be out quite a bit. They need to be calibrated for both 100C and 0C by sticking it in boiling water and recording the temperature, then sticking it in an ice bath - plenty of ice with water, leave it 10 minutes, mix it around heaps then record the temperature of the water. I had 3 old style alcohol thermomerters, one was reading 0.5 degree C higher, so I adjusted my measurements accordingly. Another one was reading 2 degrees lower, and the other one was reading 1 degree higher. The brew thermometer I have at the moment is spot on at 100C, admitedly I havent calibrated it at 0C yet.
 
Both WarmBeer and I own the Jaycar probe type thermometer (http://www.jaycar.com.au/productView.asp?ID=QM7216&keywords=thermometer&form=KEYWORD).

They both appear to exhibit an error increasing with temp, starting at around +2C near freezing and +4C near boiling when compared to an old school ethanol thermometer.

End result - I've been mashing 3C lower than I had thought :(
 
I've been wondering the same for a while - I use one of the ikea meat thermometers for my HLT (seems to read boiling OK, taking altitude etc into account) and a Mashmaster dial thermo in my MT - the Mashmaster is double checked with the HLT prob before mash in.

But I've been wanting to get a reliable, accurate glass thermometer to double check the whole system.

Can anyone recommend a reliable source of such thermometers? I can find thermometers all over the place, but it's hard to know for sure if they're accurate.
 
I've been wondering the same for a while - I use one of the ikea meat thermometers for my HLT (seems to read boiling OK, taking altitude etc into account) and a Mashmaster dial thermo in my MT - the Mashmaster is double checked with the HLT prob before mash in.

But I've been wanting to get a reliable, accurate glass thermometer to double check the whole system.

Can anyone recommend a reliable source of such thermometers? I can find thermometers all over the place, but it's hard to know for sure if they're accurate.

I made some inquiries about tel-tru thermometers recently - they are meant to be pretty damn good - http://www.teltru.com/

I forget the exact price I was quoted for the dial model I was looking for, but it wasn't cheap.
 
The ones we stock are English made Stephenson's; they come from one of the big national wholesalers so they should be available through any good home brew shop (try looking in the distilling equipment section).

Ours are all 76mm immersion thermometers, that means to get a really accurate result only the first 76mm of the thermometer should be in the hot stuff (there's a line on them to save guessing), you can get "Total Immersion" thermometers, one good place to look is photographic suppliers, they use them when developing colour prints. Otherwise a reputable Lab supply company, but again you get what you pay for, there are some out there that specialise in equipment for high schools, they tend to stock some "made to a price" thermometers as well as better ones.

You can get "Calibration Thermometers" but I think one with certificates would start around $400.

JohnnyAnchovy

That's rather the point of my original post, the really good (either electronic or analogue) equipment starts around a couple of hundred bucks, even then it still requires regular calibration.

Top end stuff is really out of the price range for most home brewers, but if your sensible and check your less expensive equipment regularly, you should get good results and great value for money.

MHB
 
Hi guys,

Its funny how some threads come along when you have issues in common . Last night I brewed for the first time since September. Crap with work and such. Any way I wasn't happy with temp setting etc and started testing with my Alc glass thermometer and temps were all over the place .

Now I have the best temp controllers some of my previous employers could afford . My back ground is in Electrical and instro control for large production companies. Some of this gear has wandered out by 13 degrees. I was aware of some temp variation some time ago but lost track and forgot. Anyway went to one of the site sponsors this morning and bought two dial indicator for HTL and mash tun .This atleast will save me getting on the steps to check with a glass thermometer once I'm happy with the dials being on target.

MHB is right on the money about checking you gear against something consistant .It doesn't take long every now and then to boil the kettle or make an ice bath .

Mitternacht Brauer
 
Yea, in my opinion having studied as a chemical laboratory technician, it doesnt matter how much you spend on a thermometer, or wether it is so called callibrated (calibrated means it should come with a cirtificate saying what the boiling and freezing temps were so you can adjust the readings it gives - check before buying!)

A bad thermometer is one that gives differing adjusted readings - eg. boiling water may read as 102C. and an ice slurry may read as 0C, thus it is not linear and hard to figure out what the actual temp is.

With the purpose of this thread being to warn about dial temp sensors, one needs to ensure that a calibrated thermometer is used to verify the accuracy of them. It could be said that every home brewer should have a regurlary calibrated thermometer at hand - every 6 to 12 months. http://en.wikipedia.org/wiki/Thermometer
 
In calibrating your thermometer, you should take into account:
Your altitude: For every c.312 metres above sea level, water boils one degree lower
Hard water boils at a slightly higher temperature.
Use a shallow pot - tall narrow pots boil at a slightly higher temperature.

These factors shouldn't affect the calibration of 0c in the ice bath.
 
I would rather rely on a standard other than water, my first choice has always been Naphthalene (sic Moth Balls) as it melts at 80.26 Co its cheap, easy to purify a small sample by recrystallising some in a test tube and its MP is very close to where I want to use the thermometer.

Just put a small piece of a moth ball into a test tube and heat the sample until it vaporises, it will recondense further up the tube.
Scrape a small amount of the condensate onto a plate and load into a capillary tube ()
Attach the capillary to the thermometer or sensor you want to calibrate (just use a rubber band), (another link)
Heat in a beaker or similar and note when the crystals turn clear (remember to keep stirring).

Might sound like a bit of dicking around but it works and is very accurate.

MHB
 
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I've sort of been meaning to ask a similar question myself.

I have two thermometers. One is a distillers thermometer. The other is one of those non-contact infra red laser ones.

I want to know, which one do you think is more accurate? Also are there any tips to ensuring an accurate reading with the non-contact one? For example if I'm measuring water, which is obviously clear, the laser itself goes through the clear water to the bottom of the pot. Will the actual temperature reading be the surface of the water though? Or will it be the temperature of the metal at the bottom of the pot? Or will it be somewhere in between?

The funny thing is I bought it and it's kind of expensive but I find myself not trusting it, and using the distilling thermometer instead. The infra red one is good for checking fridge / fermenting temps etc though.
 
The LASER just tells you where the sensor is pointing; it plays no role in the actual measurement. Thats a function of IR emission (I think its called black body radiation) from the surface.

IR thermometers dont like shiny stuff like Stainless or Aluminium, but if you put a bit of tape on the surface they read that, mine works on the surface of water (and wort) just fine

Whether either or both are accurate I cant tell you that but its why this thread was started, you need to know the answer to that question to be able to brew to your full potential.

So I guess you will have to go and calibrate one of them (I would try the glass one first)

MHB
 
What's involved in calibrating them? The ice bath and boil method above? Will that really be accurate enough if I do it?
 
Great timing of this topic, this has been on my mind for the last few months and i have been meaning to calibrate my thermometers since i noted several variances.

-mercury thermometer water boiling at ~101c
-distillers thermometer showing boiling at 106
-2-3 deg variation when i first bought my mash master dial thermometer for the mash pot
-and the need to calibrate my temp prove on my fermentation controller (brain child :icon_drool2: ).

-boiling is an easy one to set near enough to 100
-ice bath another for 0c

then to assume a linearity on my brain child probe should allow me to calibrate my mash dail guage around the 60c mark.

just burbling out loud, and many ways around it but it took this topic being raised for me to get my a$$ into gear.

EDIT: spose i now need to go back over the last 2months worth of recopies and adjust the mash and ferment temps accordingly.
 
I would rather rely on a standard other than water, my first choice has always been Naphthalene (sic Moth Balls) as it melts at 80.26 Co its cheap, easy to purify a small sample by recrystallising some in a test tube and its MP is very close to where I want to use the thermometer.

Just put a small piece of a moth ball into a test tube and heat the sample until it vaporises, it will recondense further up the tube.
Scrape a small amount of the condensate onto a plate and load into a capillary tube ()
Attach the capillary to the thermometer or sensor you want to calibrate (just use a rubber band), (another link)
Heat in a beaker or similar and note when the crystals turn clear (remember to keep stirring).

Might sound like a bit of dicking around but it works and is very accurate.

MHB



Naphthalene is a sensitizer though (repeated exposure is known to cause an alergic reaction to it - all of a sudden one day you become alergic to it). When we purified it at school, the lab teacher told us that he had to stay away from it as he had worked with it for years and now even the smallest wiff of it made his eyes water and nose run like crazy. By the end of the class he was pretty messed up!
 
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good thread, I am just going through the act of calibrating my gear

I had boiling water and my 76mm glass thermo looked to be spot on 100deg - assuming this i let it cool down to 80deg and adjusted my dial temp probe. ( is this correct or should i use 100 deg on the dial also - i assumed that the glass is doing well so it should be close at 80 also) given the dial looks different depending on a slight angle change i feel happy enough. - i used a PID for the temp control this dial is just a indication (mash)

for my chiller dial i plan to use the ice method as its much closer to the temps it will need to read.

with my PID controllers (RTD sensors) shold i use the boiling water, the glass thermo at 60-80 or some other method?

cheers
 
Does it really matter that much? I guess between 66 and 68 there is not much difference, but how unhappy are these customers,
, how far out are these thermometers? are they generally optimistic or conservative?
 
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