33 replies to this topic

[3rd party JKor]

I'm getting ready to mash in, heating up my strike water. I pull out my handy dandy, brand new calibrated lab thermometer, get the water up to temp, pour into the MLT, measure the temp with my trusty dial thermo and it's 10F less than the calibrated thermo. WTF?I go get two other digital termos and fire up my temp controller. Now I have my dial thermo, two digital meat thermometers and the thermocouple from my temp controller reading between 149 and 152, the 'calibrated' thermo reads 160. So, apparently, all four of the thermos in my house are off by exactly the same amount! riiiiiiight...

[3rd party JKor]

Hey! Whaddya know, my 'calibrated' thermometer reads 218F in boiling water!!!

[ThroatwobblerMangrove]

Hey! Whaddya know, my 'calibrated' thermometer reads 218F in boiling water!!!

Can you recal it somehow? You've just convinced me to stick with my digital meat thermo

[3rd party JKor]

it's a glass tube thermo, no recal possible. To the trash with that one.

[ThroatwobblerMangrove]

So what stage of MLPA are you in now? Or do you forget...

[chuck_d]

Hey! Whaddya know, my 'calibrated' thermometer reads 218F in boiling water!!!

How do you know what the temperature of boiling water is? It shouldn't be 218, but my point is that it's a bad point to use for checking a thermometer since so many factors affect boiling point, even the material in which the water is boiled. Best thing is to use the melting point of ice. I can hit you with a couple of links if you want the details on that process.Edit: BTW, where did you get your "calibrated" thermometer? Personally I just bought a "certified" thermometer but that's still in the mail to replace my old lab thermometer.

Edited by chuck_d, 25 May 2009 - 11:20 AM.

[ncbeerbrewer]

I just recently bought a new thermometer and have been checking it against my older one I have been using. I thought the older one was off a few degrees and I was not sure of the melting ice idea just heard of it. I too boiled up and noticed that it was off from 210 as I had expected. Then I figured with the new one that my old thermometer wasn't really broken at all. Chuck if you can post up that link. I would like to check it out as well. Hey 160 is pretty far off from 152 so maybe the majority rules. I know I would be mad if I intended to mash at 152 and really was at 160.

[chuck_d]

I just recently bought a new thermometer and have been checking it against my older one I have been using. I thought the older one was off a few degrees and I was not sure of the melting ice idea just heard of it. I too boiled up and noticed that it was off from 210 as I had expected. Then I figured with the new one that my old thermometer wasn't really broken at all. Chuck if you can post up that link. I would like to check it out as well. Hey 160 is pretty far off from 152 so maybe the majority rules. I know I would be mad if I intended to mash at 152 and really was at 160.

210? 212 is the nominal boiling temp of water.The best link is the last link, but it may be a little dense for some people so I put the more user friendly links first.The basics of calibrating at the ice point is that you want as pure a sample of water for both the ice & water, like distilled water, and you don't want to float the ice. Just put enough water in there to fill the spaces between the ice cubs where you will be sampling. It is recommended to not add water but rather let the ice melt. The reproducibility of the ice point is what makes it such a useful calibration point while boiling points can and will vary between labs.Here is some useful information on using partial immersion & total immersion thermometers properly and at the bottom they discuss a little bit about calibrating at the ice point.BYO has an article on calibrating thermometers.This page has some useful info including rejoining spirits.NIST has the real deal information on liquid-in-glass recalibration. Reading through the whole document will give you some insight into using liquid-in-glass thermometers, understanding the ice point depression that occurs while using such a thermometer frequently rather than to just calibrate others, etc. The information about how to do an ice bath is in sections 4 & 5 starting on page 7.

[xd_haze]

Here is some useful information on using partial immersion & total immersion thermometers properly and at the bottom they discuss a little bit about calibrating at the ice point.

Check to see if you have a partial immersion or a total immersion thermometer. You can't use them the same way, and I imagine you wouldn't want a total immersion thermo. mike h

[chuck_d]

Check to see if you have a partial immersion or a total immersion thermometer. You can't use them the same way, and I imagine you wouldn't want a total immersion thermo. mike h

Weird that the link doesn't persist when you quoted me. Yeah, that link also has information on how to identify which type of thermometer you have.

[jammer]

Waht do you guys think of the instant read laser thermometers? They have a problem reading off of reflective surfaces, such as a kettle, but i just dip my spoon in the wort and take a reading off the spoon.

[stangbat]

Check to see if you have a partial immersion or a total immersion thermometer. You can't use them the same way, and I imagine you wouldn't want a total immersion thermo. mike h

This is a point I was going to make. If you aren't using it right, you won't get accurate readings.

[3rd party JKor]

Hmmm, the immersion level could have been the issue. I didn't consider that.

[NomNomHopzinator]

Elevation affects boiling temp due to vapor pressure...not sure if that is your case be keep in it mind. In mountains, one should boil lower than 100C or 212F....the higher you are, the less vapor pressure there is, which = drop in boiling point of liquid. The opposite applies as well. Perhaps it was calibrated somewhere with a different elevation than where you are or you are at a low elevation. Stupid world of relativity. https://encarta.msn....ling_point.html

[stangbat]

FYI:Partial immersion - Have a line showing the immersion depthTotal immersion - Thermometer is immersed so that the depth is approximately equal with the temp on the thermometer's scaleFull immersion - The entire thermometer is immersed, usually used in a site tube on equipmentI have a partial immersion thermometer that is not accurate when you stick it in boiling water. However, it is accurate at room temp and cooler, and at mash temps. So not being accurate at boiling is not necessarily a deal breaker. You should be concerned about accuracy around the points you are typically going to use it for measurement.

Edited by stangbat, 25 May 2009 - 08:07 PM.

[chuck_d]

Perhaps it was calibrated somewhere with a different elevation than where you are or you are at a low elevation. Stupid world of relativity.

That shouldn't matter. No matter where the thermometer was calibrated it should work everywhere (well, not in a microgravity environment ). The boiling point changes, yes, but that doesn't affect the ability of a thermometer to read the temperature at which it boils. Relativity only comes into play when two observers are traveling at high velocities with respect to each other.

Edited by chuck_d, 25 May 2009 - 08:36 PM.

[Stout_fan]

Yep, those partial immersion ones are a bit tricky.The glass itself expands so keeping the temp gradient across the length of the glass is a source of error.The temperature of the room you are in also affects measurement.Designed to be read in a 25°C environment IIRC.

[BrewerGeorge]

210? 212 is the nominal boiling temp of water.

Adjusted for elevation, my water boils at 210.6. I use 210F when I'm setting the kettle controller to prevent unwanted boiling.All-in-all, though, that fact is a good argument for the ice-water calibration method.

[3rd party JKor]

Here's the one I got: ebaySays it's partial immersion. Definitely could've affected my readings, since I was immersing it about to where the temp reading was.

[stangbat]

Here's the one I got: ebaySays it's partial immersion. Definitely could've affected my readings, since I was immersing it about to where the temp reading was.

I went to the manufacturer's website and downloaded a Word document giving details about their spirit filled thermometers. It mentions that they have both total and partial immersion models. For the partial immersion, it says that the immersion depth is 76mm (3 in) for all models. It is strange that it doesn't have an immersion line on it, but who knows. Give it a try with a 3" submersion and see if that helps.Info was found here:https://www.thermcop...m/Products.htmlWord document is here.

Edited by stangbat, 26 May 2009 - 09:17 AM.