If we had NIST Certified Thermometers would we still need weekly calibration?

Hey everyone,

So in our company we calibrate our thermometers weekly using the ice bath method against a NIST certified reference thermometer.

The question that we were discussing this morning was, if we had all NIST certified thermometers would we still have to do a weekly calibration?

Yes. 

We send out NIST thermometer out annually to verify it's calibration. Just because you start with a NIST thermometer doesn't mean it can't fall out of calibration. 

How do you use the thermometers? Is it possible to be mishandled by personnel? If yes, i would still do verification but will review the frequency.

mixers have a thermometer to check batch weights and also we want to place a certified NIST wall thermometer that continuously reads and logs the cooler temp. It has a certification for 3 years 

How do you use the thermometers? Is it possible to be mishandled by personnel? If yes, i would still do verification but will review the frequency.

One little misconception someone cleared up for me a few years ago, is the difference between 'calibration' and 'verification.'

• Calibration-performed by a certified accredited vendor
  • Typically this is quarterly or annually, depending on risk or manufacturers recommendations
• Verification- Can be performed in house by a trained employee
  • Typically performed with ice bath, boiling point, by using a verification thermometer (or mixture of the 3)
  • You can usually find the recommended verification procedures and frequency under 'maintenance' sections of the thermometer's manual, however depending on your risk you might want to do this weekly, daily, per shift, etc.

EDIT: I've almost always ever just replaced the thermometers at the 1 year mark as they come calibrated. The price to send them out to a certified accredited vendor and then deal with that hassle of making sure they are up on their certifications, that they will get them back to you in a timely manner, and that they will possibly just charge you to tell you that you need a new thermometer, made it not ever seem worth getting them calibrated in my experience.

EDIT: I've almost always ever just replaced the thermometers at the 1 year mark as they come calibrated. The price to send them out to a certified accredited vendor and then deal with that hassle of making sure they are up on their certifications, that they will get them back to you in a timely manner, and that they will possibly just charge you to tell you that you need a new thermometer, made it not ever seem worth getting them calibrated in my experience.

We used to do this as well. It was cheaper to buy a new calibrated one with certificate than send away the old to be calibrated.

However, last year we started checking our thermometers against a service provider's thermometer (and got their calibration certificate as reference). This is even cheaper than buying new thermometer every year (and more environmentally friendly as well).

The service provider is the same company that helps us with pest control and is a link between us and external laboratory. So we have three areas in our agreement covered by this company. Very handy.

One little misconception someone cleared up for me a few years ago, is the difference between 'calibration' and 'verification.'

• Calibration-performed by a certified accredited vendor
  • Typically this is quarterly or annually, depending on risk or manufacturers recommendations
• Verification- Can be performed in house by a trained employee
  • Typically performed with ice bath, boiling point, by using a verification thermometer (or mixture of the 3)
  • You can usually find the recommended verification procedures and frequency under 'maintenance' sections of the thermometer's manual, however depending on your risk you might want to do this weekly, daily, per shift, etc.

EDIT: I've almost always ever just replaced the thermometers at the 1 year mark as they come calibrated. The price to send them out to a certified accredited vendor and then deal with that hassle of making sure they are up on their certifications, that they will get them back to you in a timely manner, and that they will possibly just charge you to tell you that you need a new thermometer, made it not ever seem worth getting them calibrated in my experience.

Hi Tim,

In practice, these terminologies along with Validaton often become a semantic, metrological, nightmare for the ordinary human being.

With paracetamol at the ready, welcome to digest the first 2 attachments below followed by the somewhat less head-banging 3rd file.

IIRC, "Calibration" of equipment is often referred to in haccp texts as a "Verifcation" activity for the haccp team.

Perhaps someone should (cautiously) sponsor the terminologies internal/external Calibration. :smile:

in-house Calibration - UKAS-LAB_14_Edition5July2015.pdf   308.81KB   45 downloads

calibration, Verification, etc.pdf   2.18MB   43 downloads

TCS-3LCD-calibration-procedure.pdf   7.48KB   35 downloads