How do you calibrate a thermometer?

Discussion in 'Meat Thermometers' started by daddyzaring, Apr 9, 2010.

  1. daddyzaring

    daddyzaring Smoking Fanatic

    I am going to be investing in some thermometers soon and I have no idea how to calibrate a thermometer?
  2. ddave

    ddave Master of the Pit OTBS Member SMF Premier Member

    Get a pot of water boiling and stick the thermo probe in. The thermometer should read close whatever the boiling point of water is at your altitude.

    Some dial thermos have a screw that can be used to adjust the pointer to correct the error if there is any. Most digital thermos can't be adjusted.

    Here is a web site that will calculate the boiling point at different altitudes.

    Some people also make an ice slurry (crushed ice in water) and check to see how close it reads to 32°. Most inexpensive thermos have a "sweet spot range" that they are designed for so they are more accurate in the range that they are meant for like cooking. And their accuracy or inaccuracy is not linear. For this reason, I don't bother with calibrating at 32°.

    Hope this helps.

  3. chefrob

    chefrob Master of the Pit OTBS Member

    i've always calibrated my therms (even cheap ones) in ice water and have never had any issues........
  4. graybeard

    graybeard Smoking Fanatic OTBS Member

    My opinion is this. If you are selecting dial thermometers and they are not adjustable keep looking. I went all digital because I demand accuracy.

  5. daddyzaring

    daddyzaring Smoking Fanatic

    How do I find out what my altitude is?
  6. ddave

    ddave Master of the Pit OTBS Member SMF Premier Member

    Go to Google and type in your city, state elevation and press enter.

    Worked for me. It will probably give you the elevation according to Wikipedia.

  7. hannibal

    hannibal Smoke Blower

    Great topic. Can the ET73 be calibrated?
  8. daddyzaring

    daddyzaring Smoking Fanatic

    Cool got it. I found it earlier too, but wasn't 100% sure. Now I just have to figure out how to use this thermometer. lol
    Thank you
  9. caveman

    caveman Master of the Pit SMF Premier Member

    It can be checked. I don't know about calibration. I think calibrating a digital thermo is just checking the accuracy. I use boiling water, & if I don't hit that 212° mark, then I know mine is off. I haven't had a problem with any of my wireless thermo's yet & I checked (calibrated?) them all. For one of those other "Taylor" like types, where you just stick in the meat, that can be adjusted or calibrated. Of course, if my information is wrong or off a degree° or so, someone will chime in.
  10. daddyzaring

    daddyzaring Smoking Fanatic

    Well I knew I probably can't calibrate my digital, but I just got it today, and wasn't able to figure out how to check it. Was too tire to mess with it too much. lol
  11. bbally

    bbally Master of the Pit OTBS Member

    Just calibrate with ice water. The freezing point does not change with altitude or barometric pressure.
  12. water i have aways used..even ones at work for the health inspectors
  13. got14u

    got14u Master of the Pit OTBS Member SMF Premier Member

    You can only use ice water if your thermometer goes down that far, some don't. If not boiling water for the win
  14. daddyzaring

    daddyzaring Smoking Fanatic

    It's not the temp, I just need to figure out how this thermometer works, so I can check it. lol
  15. ozark rt

    ozark rt Meat Mopper OTBS Member

    Wow. Thanks DDave. I've always thought my probes were a couple of degrees off but after checking that website it appears 210° is the boiling point of where I live.[​IMG]
  16. chefrob

    chefrob Master of the Pit OTBS Member

    i guess it takes a trusted authority..............[​IMG]
  18. dick foster

    dick foster Smoking Fanatic

    As the others have said check it at two known points for water freezing or 32F or 0C with an ice bath and boiling 212F or 100C.

    If there is an adjustment set it at boiling water as that is closer to the temp you will be cooking at.

    Most thermometers will be withing a couple of degrees and even digital is no guarantee of being spot on accurate but then again for what we're doing it's not that important anyway.

    Digital is just a means of making something easier to read, it doesn't necessarily make it any more accurate. If anything there is more to go wrong and need adjustment in all the circuitry involved with an electronic thermometer. Remember one of the best lab standard thermometers is still a simple mercurial type.

    If you have a digital type then the sensor used determines the accuracy more than anything else. For good accuracy you want a platinum type like a PT100 over a thermocouple or PN junction type sensor.

    Platinum changes it's resistance with temperature and platinum based sensors are typically more linear in response than the other types. They also usually cost no more than the other sensor types.

    The PT100 sensor I use in my smoker along with a PID controller, I got for 5 bucks and it has a stainless steel housing. Perfect for the task. I tweaked it at the boiling point a couple of degrees but that was probably due to an offset in the ciricuit instead of the sensor itself.
  19. great info thx

Share This Page