Don't forget to calibrate

Discussion in 'Poultry' started by tlhiv, Nov 23, 2009.

  1. tlhiv

    tlhiv Smoke Blower

    Ladies and Gentlemen,

    If you're planning on smoking a turkey this week, don't forget to calibrate your thermometers. For pulled pork and brisket, say, there is little risk when missing your target temperature by a few degrees in either direction; however, for poultry we must be extra careful.

    My plan is to remove my bird from the smoker when the temperature in the thickest part of the breast is about 165°F since I am assuming that the bird's internal temperature may continue to rise a few more degrees after it has been removed from the heat. If we finish our bird at too cool an internal temperature, then we face a serious undercooked poultry health danger. If we finish our bird at too high an internal temperature, then we run the risk of drying out our bird.

    So, don't forget to calibrate these probe thermometers before your smoke. Remember that water freezes at 32°F and boils at 212°F (at standard pressure). So, if you live in higher elevations (where your pressure is less), make the necessary adjustments. For example, in Denver your water probably boils at about 202°F.

    I recommend checking your thermometers in a glass of crushed ice water, say, and in a pot of boiling water. I just did these tests on four of my thermometers, and I got the following results:

    #1 = 32°F and 213°F
    #2 = 33°F and 211°F
    #3 = 36°F and 215°F
    #4 = 32°F and 213°F

    As you can see, thermometers #1, #2, and #4 are pretty accurate. However, thermometer #3 is reading about 3-4°F too high. Therefore, I will carry the bird that is using this thermometer to probably 169°F before removing it from the heat.
  2. mballi3011

    mballi3011 Smoking Guru OTBS Member SMF Premier Member

    Thanks for posting this thread for it is really important that people have their thermometers checked to see if they are smoking to the right temp. and the reason why something are dry or under cooked.
  3. raceyb

    raceyb Smoking Fanatic

    Bump! This thread was 3 pages back on the forums and I thought it greatly deserved to be bumped. Maybe a temp sticky until all the holidays are over?
  4. luvdatritip

    luvdatritip Smoke Blower

    This is a good thing to do prior to each smoke, however since one is checking the linear accuracy of the therm, I don't think you can calibrate a probe therm. It is what it is.
  5. raceyb

    raceyb Smoking Fanatic

    Most of the smokes we do won't matter if the end product is a few degrees off, however for poultry, as the OP pointed out, a few degrees can make all the difference in the world.

    The calibration is done in the head. He has numbered his probes and he will make a mental adjustment on probe number 3. While it is not a physical calibration, it is a calibration nonetheless.
  6. tlhiv

    tlhiv Smoke Blower

    Indeed Raceyb. In fact, I have even marked on my ET-7 transmitter which port each probe was plugged into to make sure I have the exact same setup when smoking the turkeys. To me, it's just that important.
  7. bbq engineer

    bbq engineer Master of the Pit OTBS Member SMF Premier Member

    Great Reminder, and a simple thing to do to ensure that your bird is properly cooked, and not dry as cardboard. With a calibrated thermo, I will even cheat on the low side a few degrees, as the internal temp will continue to rise a few degrees after I remove it from the smoker and foil tent it to rest. I guarantee that if you brined your bird to begin with, juice will run out of your breast.

    If you have a bird with a one of those cheap plastic "POP UP THERMOMETERs", pull that thing out and throw it away. If you go by that it is guaranteed to produce a dry and barely palatable cardboard turkey. It would be like using the fire alarm as a dinner bell.

    Points to Tlhiv [​IMG]
  8. bearcarver

    bearcarver Smoking Guru OTBS Member

    Hmmm, you must be an assistant professor of Mathematics (my favorite sport).

    Thanks for your well laid out method. I saved it as a reminder.

  9. kurtsara

    kurtsara Smoking Fanatic OTBS Member

    I am not arguing here just asking but how do we know the temp of a glass of ice water, it's not 32° or it would be solid wouldn't it?

    I have only checked mine with boiling water but some say ice water is more accurate

    What's your opinion?
  10. tlhiv

    tlhiv Smoke Blower

    The freezing point of water is the point at which water goes from a liquid state to a solid state, and this temperature is 32°F. That is, if all of the water molecules are at that temperature (assuming standard pressure), then the water becomes ice. When we see water that is "partially" frozen, what this means is that some of the water molecules are at 32°F and some are at slightly higher temperatures. Similarly for boiling water. Once water molecules reach 212°F, it transforms from a liquid state to a gaseous (no burrito or bean jokes here) state. However, when the water in your pot is boiling, you'll see steam coming out (and this water has already reached the 212°F temperature and has been transformed) and you'll also still have liquid water in the pot (and this water is very close to 212°F but not quite there).

    So, theoretically you're correct. 32°F is the freezing point of water, but if the water is 32.01°F, say, then the water is not yet frozen. I was basing my test on the fact that my water was not 32°F but very close to it and using that for my calibration.
  11. silverwolf636

    silverwolf636 Smoking Fanatic OTBS Member

    As soon as I saw this tread a light turned on. I went in and checked my 2 analog and my 1 digital. It turned out that the 1 analog was 4 degrees higher than the other and this digital was in between.

    Thanx for the info and reminder

  12. bbq engineer

    bbq engineer Master of the Pit OTBS Member SMF Premier Member

    What we are looking for in the home environment is something that is readily available to use as an assignable standard...Ice water and boiling water are as close to defined standards that we can come.

    There are some variables that will affect boiling water, such as barometric pressure and altitude...for example, water will boil at ~202° if you are in Denver (5280') and ~212° along the coast. You can use this calculator to determine the precise boiling point for water at your elevation.

    Altitude has very little effect on the change of water from a liquid to a solid, however. The freezing point of water increases with a decrease in the pressure applied to it, therefore the freezing point of water will be lower at high altitude than it will be at sea level (low pressure - vs - higher pressure). This effect is , however, very, very small. The freezing point of water rises a mere hundredth of a degree per atmosphere of decrease in

    Therefore, if you calculate the boiling point of water using the elevation of your location and the current barometric pressure, it will be equally as suitable as utilizing ice water for setting your thermo...otherwise, ice water would be the more accurate standardization point. I won't even get into non linear deviations of the devices themselves. I do believe, however, that it is always better to calibrate close to the acutal usage temp...and that would be closer to 212° than 32°. So now that we understand the science, I suggest that you calculate the boiling point of water for your elevation and use that number for your calibration.

    Hope that helps.
  13. luvdatritip

    luvdatritip Smoke Blower

    Since these probe therms get their information from the probe(right or wrong) the head will only read what the probe tells it. The head or main unit in non adjustable. If a probe is few degrees off, either on the plus or minus side, one would have to check it at different temp readings, hence the linear accuracy. Another great use for the Thermapen. Imo, a few degrees either way, even with poultry won't make much difference. Case in point; if probe #3 shows 215 degrees in boiling water, how far off is it at 200 degrees or more importantly 140 degrees? You get the point.
    While it is a good thing to check the linear accuracy of the probe therms, my point was that you cannot physically or mechanically adjust the readings that you get.
  14. geek with fire

    geek with fire Master of the Pit OTBS Member

    It's also important to note that most people's probes are thermistor sensors which are (for the most part) non-linear. I bring this up because you could be off 4 degrees on one end, 2 degrees off on the other end and dead on in the middle. This make calibration tough. If you cook a lot of poultry (and we do) a great investment is a Thermapen, which uses thermocouple sensors. Super fast and dead on.

    Great post Troy.
  15. alx

    alx Master of the Pit OTBS Member

    Very good advice...My thermapen or taylor commercial model are my final internal temp probe as well.....
  16. raceyb

    raceyb Smoking Fanatic

    Thats why he does two tests, one with ice water and one with boiling water. If he only did boiling water and it read say 217. it would be hard to tell how far off it might read at say, 165 degrees. By doing the ice test as well, he can see if it is a linear or a static fault with the thermo. :)

    Not trying to argue with ya, but a few degrees is important with poultry. If I pull my turkey at 160 degrees and expect it to climb by 5 degrees as it rests, what of my thermo was off by 5-6 degrees on the low side? My turkey will NEVER hit 165 and the salmonella would have not been totally killed off.

    I agree that in most cases, ribs, brisket, shoulder, hams, etc, a few degrees won't matter. In the case of poultry, EVERY degree matters.
  17. luvdatritip

    luvdatritip Smoke Blower

  18. alx

    alx Master of the Pit OTBS Member

    Some folk like to argue...LMBO.Knowing your smoker and using accurate thermos is all you need...Retired friend of mine was a well known executive chef and he went by feel and time-not recommended for most,but years of experience and knowing your smokers/ovens is important....The best brisket cooks i know rarely probe but use the cheek test....Definetly recommended for 99% of folk to probe meat....But then the wiggle test on legs and clear juices was what most did before thermos...which was not long ago.....I dont remember mass kill offs in the old days from salmonella etc...Safety first though.....

  19. bearcarver

    bearcarver Smoking Guru OTBS Member

    I have enjoyed this discussion. I think it did me some good too:
    I had a "Thermapen" on my Christmas list, but it was so expensive ($99) I changed it to a much cheaper "instant" thermometer. After reading the comments about the "Thermapen" on this thread, I changed my wish back to the Thermapen.

    I would presume that was a wise decission.

    Is that the best price out there?

    Thanks gang,
  20. ldrus

    ldrus Smoking Fanatic OTBS Member

    Roflmbo..........Just to clear things up on the calibration for ya he is saying the calibration is done in your head not the head of the gage silly!!!! you just have to remember how far off yours is reading and adjust (mentally)

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