Temperature Calibration for a Storage Refrigerator

[sh.samir]

We are operating electro-technical calibration lab. We want to calibrate our client's refrigerator (for blood storage) having measurement in +5 Deg. C.
The temp. meter don't have specified TC / RTD type used to measurement.
When we measure TC mV our master instrument measures 2.3 V DC
We dont know which type TC gives this type of reading we aware only about mV or resistance.
Please provide details (with table if available) the Tc type used in this measurement.

 

[BradM]

Re: Temperature calibration

Hello there! Welcome to the Cove!!

Are you saying you have a meter that can read thermocouples, and you are looking for what type of thermocouple to use?

First, let's assume that you have a calibrated meter. You will need to procure a calibrated thermocouple to use with that meter. Since you stated refrigerator, I am assuming this is in the neighborhood of 3C to 20C or so. Lots of thermocouples will work; I am preferential to Type T.

Second, there are two things you can do on the refrigerator. You can verify the accuracy of the controller (if it has an indicating type). Place your calibrated thermocouple tip next to the tip of the controller and verify its accuracy.

Next, you could verify the uniformity of the refrigerator. This would be to verify any temperature variations depending on the location inside the refrigerator. Do note, the uniformity may change depending on how much material is loaded into the refrigerator.

Not sure any of that helps. Please feel free to clarify if I got off on the wrong path.

 

[somashekar]

Re: Temperature calibration

Hello there! Welcome to the Cove!!

Are you saying you have a meter that can read thermocouples, and you are looking for what type of thermocouple to use?

First, let's assume that you have a calibrated meter. You will need to procure a calibrated thermocouple to use with that meter. Since you stated refrigerator, I am assuming this is in the neighborhood of 3C to 20C or so. Lots of thermocouples will work; I am preferential to Type T.

Second, there are two things you can do on the refrigerator. You can verify the accuracy of the controller (if it has an indicating type). Place your calibrated thermocouple tip next to the tip of the controller and verify its accuracy.

Next, you could verify the uniformity of the refrigerator. This would be to verify any temperature variations depending on the location inside the refrigerator. Do note, the uniformity may change depending on how much material is loaded into the refrigerator.

Not sure any of that helps. Please feel free to clarify if I got off on the wrong path.

Hi and welcome here Samir.
Did you also take a look at THIS thread ~~~

 

[alex.Kennedy]

An un-calibrated test instrument is a useless piece of equipment and regulators world-wide would close you down for even contemplating the use of such an instrument. There are literally dozens of configurations for thermocouple wire combinations. These are selected depending on the temperature range and response times that you are trying to measure.

I think your first task is to study your own national requirements for the work you are undertaking. (or proposing to undertake).

Calibration must be performed using test instrument or standards (used in their calibration) that are traceable to national standards. You must hold calibration certificates for all your test instrumentation and these certificates must clearly show this traceability.

Alex

 

[dv8shane]

We are operating electro-technical calibration lab. We want to calibrate our client's refrigerator (for blood storage) having measurement in +5 Deg. C.
The temp. meter don't have specified TC / RTD type used to measurement.
When we measure TC mV our master instrument measures 2.3 V DC
We dont know which type TC gives this type of reading we aware only about mV or resistance.
Please provide details (with table if available) the Tc type used in this measurement.

Determine the clients process requirements and have them agree to this in writing. Next as Brad mentioned use a calibrated system (probe readout) to monitor the results. I would add it would be better it both the system probe and the measuring probe were as close as possible. The system used to measure should have an accuracy at least 4 times better than the unit under test (the measuring system includes the UUT repeatability and resolution) or guard banding of the tolerances may be needed to issue a statement of conformance.

 

[supremo]

From what you have stated, it is clear that you have no established procedure for calibrating a temperature chamber.

All the replies above are very helpful. But everything must be documented first.

Establishing work instruction for calibration of temperature chambers must be your first step.