3 Tools To Measure Mean Kinetic Temperature (With a downloadable Excel spreadsheet calculator!)

Posted on: April 4th, 2014 by Dickson 15 Comments

Mean Kinetic Temperature: used by many but understood by few. For the food and pharma industries, knowing the Mean Kinetic Temperature (MKT) of a product or group of products during storage or shipment can be crucial to quality, safety, and falling in line with your auditing agency. Below we’ve outlined 3 tools below to help you calculate the MKT of your processes. But first, a brief explanation of what it actually is . . .

MKT is a number. That number is expressed in Celsius, Fahrenheit, or Kelvin, thus it is a number that expresses a temperature value. To expand a little further, MKT is a temperature value that attempts to simulate how a product was affected by temperature over a period of time. Think of it like this: you have a pharmaceutical drug recently manufactured an en route to a storage facility. The temperature at the facility it was coming from was 43F, the truck it was shipped in was 27F, and the new storage facility is 38F. MKT simulates the effect of all those temperatures on your product.

1. The Formula (Difficulty Level = Hard)

Mean Kinetic Temperature Formula

For all you math whizzes, for all you quadratic formula know-it-all’s, the formula just may be right for you. For the rest of us, easier options await your scroll!

 

2. Excel Sheet Calculator (Difficulty Level = Medium)

We had one of our engineers/programmers put together a spreadsheet that will allow you to enter in temperatures from your data logger, and then automatically calculate your Mean Kinetic Temperature with the push of a button. The link to download the Excel file is below, and contact content@dicksondata.com if you’d like more information.

Mean Kinetic Temperature Excel Sheet Calculator

 

3. DicksonOne (Difficulty Level = Easy)

DicksonOne automatically calculates your MKT for you. Yup, it just appears on the screen next to you temperature and humidity values. Seriously, it does. Look at the screenshot below. And, for more information on DicksonOne, go to DicksonOne.com, or give us a call (630.543.3747). We’d love to chat.

Mean Kinetic Temperature DicksonOne

 

 


7/1/2015: This post was updated to change the Default Activation Energy of the Downloadable Excel Calculator from 85 kJ/mK to 83.14472 kJ/mK

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15 Responses

  1. muhammed says:

    how can i convert this equation to be suitable for Celsius Temp input data?
    thanks

    • Michael says:

      Hi Muhammed! You can choose Fahrenheit or Celsius in Column F, Row 4 by inserting “F” or “C” respectively. By changing the “F” to “C’ it will convert the equation for you.

  2. Stefan says:

    Thank you for the Excel Sheet. I appreciate that. However, in the Index column it is assumed that the time interval for all data points is equal, correct?

  3. Michael Bresnick says:

    The Excel sheet shows an activation energy approximately 10x the gas constant. The formulas seem to ignore the fact that for these magnitudes, the units of the activation energy includes kJoules, while the gas constant includes Joules. Why is the factor of 1000 difference ignored in the calculation.
    Thank you
    Michael

    • Michael says:

      Hi Michael!

      Great question. I spoke with one of our engineers about your question, and have outlined their response below!

      The formula can ignore the difference because the numerator has a factor of activation energy divided by gas constant. Also, the denominator has the natural log of a factor of the exponentiation of the factor of the activation energy divided by the gas constant in each term…so you end up with a factor of 1000 in the numerator divided by a factor of 1000 in the denominator and it cancels out.

      Let us know if this helps!

      -Michael at Dickson

      • Michael Bresnick says:

        Thanks for your reply, Michael. I appreciate that you’ve taken the time to consider this. Unfortunately, I believe your engineer is wrong, but would be happy to find out otherwise. I don’t think the H/R term can be factored out of the sum of the exponentials. I’ve set it up in an Excel spreadsheet using formulas (instead of VBA) and two equal time intervals with temperatures of 20C and 100C. I get results of 55.3 (ignoring the units difference) and 90.6 (addressing the units difference). I’ll send the spreadsheet if you’d like (need email). Note that the ratio of the activation energy / gas constant is 10,000 when units are recognized. General Chapter 1079 of the USP, the gas constant is stated as 8.3114 x 10^(-3) kJ/ mole-degree. This means that someone executing by the MKT formula would be recognizing the units. I’ve made this mistake initially and once I realized the difference it makes, I recognized that the issue is that exponentiation doesn’t accommodate factoring over the sum. The magnitude of the effect depends on the range of temperatures. I will happily accept that it is my error if I see a working example, or even better a derivation.

  4. serge says:

    I am conducting temperature mapping in cold rooms for vaccines with more than 1200 data / records. How can I use the excel sheet and extend the data in column D? What about the variables, no explanations on how to complete?

    • Michael says:

      Serge,

      Thanks for your question. First, Sheet #1 of the Excel document should have instructions for using the formula.

      The data in Column D is automatically generated after you click the black “Calculate MKT” button. So, to add your 1200 data points, simply copy and paste them into Column B, click “Calculate MKT,” and you’re done! The data will display in Column D.

      Hope this helps.

      -Michael at Dickson

  5. serge says:

    Hi, am conducting temperature mapping for vaccine cold room and have more than 1,200 data / records. How to use the excel sheet so the variables are calculated (the sheet is for 48 records). What about the variables, no explanations. thanks

  6. Michael says:

    Serge,

    See comment above.

    -Michael at Dickson

  7. Tamara says:

    Thank you for the calculating sheet. What would be a “normal” value of the result after the calculating?

  8. Toryalai Hart says:

    Hi Serge,

    All of the PQS specification requirements that I’ve found for fridges and cold rooms all have this paragraph in them:

    “Acceptable temperature range: The acceptable temperature range for storing vaccine is +2°C to +8°C. However, transient excursions outside this range will be tolerated, within the following limits:
    • No excursion must exceed +20°C.
    • No excursion must reach 0°C.

    The cumulative effect of any excursions within the above range will be assessed over the five day period of the day/night test. For this test, the calculated mean kinetic temperature (MKT) 1 must remain within the range +2°C to +8°C when the default activation energy is set at 83,144 kJ per mol. Using the recorded temperature data, an MKT figure will be calculated for
    each sensor. The worst-case result will determine the outcome of the test. Excursions in other tests will be noted and must not exceed the defined upper and lower limits.”

    Spreadsheet provided uses that same value for activation energy, but with more significant figures.

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