16 replies to this topic

[Big Nake]

Every once in awhile, I look at my various tools and decide I no longer trust them. My pH meter is toast (apparently) and so I also decided to check the accuracy of my Thermapen since it's actually older than my pH meter. I got this off the Thermapen site. Apparently it only applies to their product although I'm pretty sure the instructions for making the ice bath would apply to any thermometer. They say...An ice bath test is the easiest way to test the accuracy of any thermometer, but only if the ice bath is created properly. Many internet videos notwithstanding, an icebath is NOT just a glass of ice water. Follow this four-step process carefully to create a proper ice bath:Step 1: Fill a large glass to the very top with ice (crushed ice is preferred but not required).Step 2: Slowly add very cold water until the water reaches about one half inch (1 centimeter) below the top of the ice. Note: If the ice floats up off the very bottom of the glass at all, the ice bath will likely be warmer than 32°F (0°C). Pour off any excess water.Step 3: Gently stir the ice mixture and let it sit for a minute or two.Step 4: Insert the probe of the thermometer being tested about 2 inches (5 centimeters) into the ice mixture and gently stir while you take your reading.Note: Be sure to keep stirring gently. If the tip of your thermometer probe comes to rest against a chunk of ice, it will show a temperature below the ice point and if it comes to rest against the sides or bottom of the glass, it may read higher. Your Thermapen will drop to 33°F (1°C) within 3 seconds and will continue to approach 32.0°F (0.0°C) over the next 2 or 3 seconds. The final resting temperature should be between 31.3°F and 32.7°F (-0.4°C and 0.4°C) (worst case). If your Thermapen is accurate in a proper ice bath, it will almost certainly be accurate at all other temperatures.I tried this on mine and it rested at 31.9° which suggests it's all good. That temp range of 1.6° is a little off-putting as we typically shoot for relatively precise mash temps.  Mine measured .6 higher than the low and .8 lower than the high so it seems to be close to the middle of the range.  Cheers Beerheads.

Edited by Village Taphouse, 11 February 2015 - 08:03 PM.

[neddles]

I tried this on mine and it rested at 31.9° which suggests it's all good. That temp range of 1.6° is a little off-putting as we typically shoot for relatively precise mash temps.  Mine measured .6 higher than the low and .8 lower than the high so it seems to be close to the middle of the range.  Cheers Beerheads.

 

Nice info. If I am reading that correctly then a thermapen is going to be no more than 0.8ºF off from your target temp, not 1.6ºF. And yours looks like it is only 0.1º

 

My wife broke ours several weeks back and I am using a brand new one so it had better be accurate!

[Big Nake]

Nice info. If I am reading that correctly then a thermapen is going to be no more than 0.8ºF off from your target temp, not 1.6ºF. And yours looks like it is only 0.1º  My wife broke ours several weeks back and I am using a brand new one so it had better be accurate!

Yeah, it sounds like they have a longer life than the meters do and these guys are VERY proud of their thermos and it appears to be for good reason. Bummer that your wife broke yours but I'm not surprised you picked up a new one. Have you ever stuck yourself with the probe? That thing is sharp!  

[SchwanzBrewer]

Love my thermapen.

[denny]

I wouldn't trust that method to work with anything other than a Thermopen.  When I've tried it with other thermos in the past, they were still off at mash temps (since I don't mash at 32F!).

[jammer]

Love my thermapen.

 

 

this.

[BlKtRe]

For $20 I got a Thermoworks Pocket tested against NIST Traceable and the Thermopen. I see no reason to buy the Thermopen at this time when for $70 cheaper you get the same thing. 

 

 

https://www.thermowo...st/rt301wa.html

[Corbin]

I wouldn't trust that method to work with anything other than a Thermopen.  When I've tried it with other thermos in the past, they were still off at mash temps (since I don't mash at 32F!).

Denny how do you test your thermometers? I need to check on mine to make sure it's accurate.

[denny]

Denny how do you test your thermometers? I need to check on mine to make sure it's accurate.

 

I bought a calibrated, certified lab thermometer and test my brewing thermos against it at 150F.

[darkmagneto]

I bought a calibrated, certified lab thermometer and test my brewing thermos against it at 150F.

 

Not to be a dick, but how do you know it's at 150F?

 

Just curious as I've never heard of a scientific test on calibration at 150F.  Science has proven two thermal occurrences.  Which is why we calibrate to those.

 

Again, just curious on how you achieve 150F with accuracy.  Details are much appreciated.

[BlKtRe]

Not to be a dick, but how do you know it's at 150F?

 

Just curious as I've never heard of a scientific test on calibration at 150F.  Science has proven two thermal occurrences.  Which is why we calibrate to those.

 

Again, just curious on how you achieve 150F with accuracy.  Details are much appreciated.

 

Gotta trust something. I trust a glass lab that Denny talks about and the Thermoworks I posted above. 

[Brauer]

Not to be a dick, but how do you know it's at 150F?

 

Just curious as I've never heard of a scientific test on calibration at 150F.  Science has proven two thermal occurrences.  Which is why we calibrate to those.

 

Again, just curious on how you achieve 150F with accuracy.  Details are much appreciated.

Spirit thermometers are linear from 32 F to 100 F, so you can check their calibration, in ice water and boiling water and, if accurate there, they will be accurate at 150 F. Unless the scale is printed wrong, of course, but that shouldn't be a question with a lab thermometer. Then, you calibrate your digital or dial thermometer against your spirit thermometer at ~150 F. 

 

Just remember that lab thermometers can go bad, usually due to a gap in the column, so they need to be calibrated, as well. They can often be repaired by shaking the spirit down to the bulb boiling followed by an ice bath.

 

For good measure, I like to check my dial thermometer at 2 points, usually 148 F and 160 F, periodically, just to make sure that it is working correctly, because you can adjust a broken thermometer to 150 F, but if it isn't working, it's not going to read correctly when you go to use it. I've had thermometers do this to me, calibrating properly at 150 F, but reading around 155 F at 170 F.

Edited by Brauer, 14 February 2015 - 06:16 AM.

[BlKtRe]

Spirit thermometers are linear from 32 F to 100 F, so you can check their calibration, in ice water and boiling water and, if accurate there, they will be accurate at 150 F. Unless the scale is printed wrong, of course, but that shouldn't be a question with a lab thermometer. Then, you calibrate your digital or dial thermometer against your spirit thermometer at ~150 F. 

 

Just remember that lab thermometers can go bad, usually due to a gap in the column, so they need to be calibrated, as well. They can often be repaired by shaking the spirit down to the bulb boiling followed by an ice bath.

 

For good measure, I like to check my dial thermometer at 2 points, usually 148 F and 160 F, periodically, just to make sure that it is working correctly, because you can adjust a broken thermometer to 150 F, but if it isn't working, it's not going to read correctly when you go to use it. I've had thermometers do this to me, calibrating properly at 150 F, but reading around 155 F at 170 F.

 

This. If you choose to get a spirit thermo make sure you check and see if its partial immersion or full immersion. That just means where the temp is taken on the thermo itself. There are lines where the liquid needs to be at to get a proper reading. I use a partial immersion when calibrating because the thermo only needs to be submerged a few inches vs all the way to the temp you want to read on the full immersion. This way a normal sized pot on the stove can be used. 

Edited by BlKtRe, 14 February 2015 - 07:16 AM.

[Brauer]

This. If you choose to get a spirit thermo make sure you check and see if its partial immersion or full immersion. That just means where the temp is taken on the thermo itself. There are lines where the liquid needs to be at to get a proper reading. I use a partial immersion when calibrating because the thermo only needs to be submerged a few inches vs all the way to the temp you want to read on the full immersion. This way a normal sized pot on the stove can be used. 

I bet that a lot of full immersion thermometers are used incorrectly. 

[denny]

Not to be a dick, but how do you know it's at 150F?

 

Just curious as I've never heard of a scientific test on calibration at 150F.  Science has proven two thermal occurrences.  Which is why we calibrate to those.

 

Again, just curious on how you achieve 150F with accuracy.  Details are much appreciated.

 

Because my certified calibrated thermometer tells me it is.

Because my certified calibrated thermometer tells me it is.

 

And keep in mind that this is not just any spirit filled glass thermo.  I paid about $300 for the thing, I care for it like a baby, and I trust that it works.

[BlKtRe]

I bet that a lot of full immersion thermometers are used incorrectly. 

 

Probably. Kinda of a pain to use but I used to use them in the mash to get down deeper into the grain. 

[Stout_fan]

I have a certified ( one standard removed from NIST.  ie: calibrated against a secondary standard) that is laser marked after production.  It wasn't cheap, but I wanted my color E6 process to be right on as temps affect color saturation and contrast.

 

Now I use use it to calibrate my brewing thermometers (also spirit filled).

Ah, ya gotta love the digital revolution.

Great for beer, lousy for photography(at least my rather large investment).