Verifying Calibration of Thermocouples at different Temperatures

G

GTJunghoon

#1
I'm attempting to draft procedures that will verify the accuracy of thermocouples before being used to gather temperature data of chambers (coolers and incubators).

I want to purchase a portable thermocouple calibrator . The verification will require the calibrator to send temperature signals to the thermocouple, and operators will compare the temperature displayed on the calibrator (Tcal) to the temperature displayed on a computer (thermocouple -> DAQ -> computer) (Tcpu). The thermocouple passes if Tcpu is within 0.5C of Tcal.

If I'm verifying the thermocouples for a cooler that maintains 2-10C, are my verification points different than if I was preparing for an incubator that maintains 55-60C?

Covers, I'll appreciate feedback on the design. It can't be this simple. :thanks:
 
Elsmar Forum Sponsor

Ninja

Looking for Reality
Staff member
Super Moderator
#2
I'm attempting to draft procedures that will verify the accuracy of thermocouples before being used to gather temperature data of chambers (coolers and incubators).

I want to purchase a portable thermocouple calibrator . The verification will require the calibrator to send temperature signals to the thermocouple, and operators will compare the temperature displayed on the calibrator (Tcal) to the temperature displayed on a computer (thermocouple -> DAQ -> computer) (Tcpu). The thermocouple passes if Tcpu is within 0.5C of Tcal.

If I'm verifying the thermocouples for a cooler that maintains 2-10C, are my verification points different than if I was preparing for an incubator that maintains 55-60C?

Covers, I'll appreciate feedback on the design. It can't be this simple. :thanks:
Agreed, it can't be that easy.

What is the range of temperatures you are measuring with your thermocouples?

My first reaction to the technique is that you are verifying the meter...not the thermocouple. What are you using to verify the thermocouple itself?

The purpose of a thermocouple is to generate a known (predictable) voltage given a temperature gradient. I don't see a temperature gradient anywhere in that cool piece of equipment.

The readout/meter/display translates the voltage signal to a displayed temperature. Sending a voltage signal to the meter and getting the correct temperature on the display verifies the meter...but not the thermocouple.

A properly functioning meter hooked up to a drifted thermocouple will still give you the wrong answer.

I ask about the temperature ranges to get a feeling for the speed of drift.

For a type J or K, they are pretty stable. For a Type R or B, that meter is a cool gadget that is useless.

I have looked into getting calibrated thermocouples (B and R) for furnace verification...and not a single vendor will calibrate a thermocouple that is not brand new. They'll sell you a new one, calibrated, and good for a single use, but the TC drifts too fast to bother trying to recalibrate a used one.
 
G

GTJunghoon

#3
Ninja,

That's a pretty good point. I plan on using Type-T thermocouples for temperatures ranging from 0-60C.

Do you have any experience with ASTM E2846-11?
 
Last edited by a moderator:

Ninja

Looking for Reality
Staff member
Super Moderator
#4
I don't know much about the Type-T.

Copper from 0-60C is not something that raises any flags for me though...

Just thinking out loud:
If you verify/validate/calibrate/check your meter using your cool gadget, then hook a thermocouple to it and put it in a known temperature gradient and get a correct reading (within tolerance), is that a defensible technique for the standard or customer you are trying to comply with?

What makes you think the cool gadget is correct/calibrated/valid ? Is it calibrated somehow?

Another approach is to have your TC's calibrated/validated by bringing an outside company in...and see what equipment they use to do it. Then go shopping for that.
 

Hershal

Metrologist-Auditor
Staff member
Super Moderator
#5
A portable thermocouple calibrator, at least a good one, will allow you to verify the thermocouple electrically. Your calibrator however needs to be itself calibrated and you need the uncertainty. Why?

You need to know how much error you begin with, before you start checking.

Hope this helps.
 

Ninja

Looking for Reality
Staff member
Super Moderator
#6
A portable thermocouple calibrator, at least a good one, will allow you to verify the thermocouple electrically. Your calibrator however needs to be itself calibrated and you need the uncertainty. Why?

You need to know how much error you begin with, before you start checking.

Hope this helps.
Hi Hershal,

Just for my own learning...what do you mean when you say "verify the thermocouple electrically".

I am curious as to what can be gained here that I might use as well...

Thanks in advance!
 

BradM

Staff member
Admin
#7
There seems to be a mix of two things here. There is the calibration of the thermocouples and the calibration of meter that will read the thermomcouples.

You can calibrate them both as a loop (thermomcouples connected to the measurement device). However you will need a calibrated master thermocouple/ temperature meter to verify the loop devices. It should be of sufficient accuracy, which is why Hershal suggested making sure you have a calculated total uncertainty.

Otherwise, you can electronically simulate the thermocouple signals using the Altek meter (the link you provided), assuming there is sufficient accuracy. Then, you will need to devise a solution for calibrating the thermocouple sensors/wires.

If you are going to calibrate the sensors/wires, you will need to assure you have a low temperature calibration dry block or other suitable means to "create" a uniform test environment.
 
G

GTJunghoon

#8
To clarify, I can verify the accuracy of the thermocouple with the Altek meter (assuming it's acceptable). If the thermocouple is out of calibration, then I can discard it and replace it with a thermocouple that has been verified as calibrated.
 

BradM

Staff member
Admin
#9
To clarify, I can verify the accuracy of the thermocouple with the Altek meter (assuming it's acceptable). If the thermocouple is out of calibration, then I can discard it and replace it with a thermocouple that has been verified as calibrated.
At this point, you aren't interested in verifying any of the process/monitoring instruments that are permanently attached to the coolers and incubators. You are only interested in verifying the instrumentation used to map the chambers for temperature uniformity. Correct? Let me know if I am wrong on that one.

So for the mapping instrumentation,

A. The meter/recorder/ indicator that the mapping thermocouples will be connected to.
B. The mapping thermocouples.
C. Calibrated temperature sensor.
D. Calibrated meter for temperature sensor.
E. Uniform calibration environment (dry block, oil bath, etc.)

A and B; and C and D; may be calibrated as a loop; or they may be calibrated individually.

So, you first have C and D calibrated with sufficient accuracy to Calibrate A and B. So to keep it simple, if A+B must meet ?1?C, then C+D need to have an accuracy of around ?.25?C.

So then, if you are going to calibrate B, you will need E. The uniformity should be good enough that it does not affect the ?.25?C accuracy.

I listed things in accuracy to keep it simple. The better way would be to calculate the uncertainty of A and B; then evaluate against the uncertainty of C, D, and E collectively.

I hope I did not confuse things here. :)
 
#10
If accuracy is important, you can always specify a SLE type thermocouple (special limits of error). Usually the SLE types are 1/2 of the standard thermocouple tolerance. For example, a standard type T is ?1?C or ?0.75%RDG; however, a type T SLE would be: ?0.5?C or ?0.4%RDG.
 
Thread starter Similar threads Forum Replies Date
F Checking Gages In and Out and Verifying Calibration Status Calibration and Metrology Software and Hardware 8
N Verifying Calibration of Hardness Gauge vs Actually Calibrating It General Measurement Device and Calibration Topics 2
K Verifying gas tight glass syringe used for making standards General Measurement Device and Calibration Topics 4
D Tolerance when verifying an analytical balance General Measurement Device and Calibration Topics 3
L Verifying training effectiveness for procedure changes ISO 13485:2016 - Medical Device Quality Management Systems 4
X Heat Treat - Verifying mechanical properties on heat treated material per the ASTM Manufacturing and Related Processes 6
G Acceptance Criteria when Verifying a Gauge General Measurement Device and Calibration Topics 2
G Verifying the Documents we have in place AS9100, IAQG, NADCAP and Aerospace related Standards and Requirements 2
C Verifying In House Laboratory Weight Sets General Measurement Device and Calibration Topics 2
T What is clause ISO9001:2008 for Acc/Rej Criteria and Verifying QA process Internal Auditing 2
R Verifying Documents have been removed or destroyed once the Retention Period expires ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 12
J Verifying a Standard with a Standard using Micrometers General Measurement Device and Calibration Topics 10
Q Basis for Verifying Corrective Actions and Effectiveness ISO 13485:2016 - Medical Device Quality Management Systems 12
AnaMariaVR2 Tracking Water Resistivity - Verifying Reverse Osmosis Water Purification Misc. Quality Assurance and Business Systems Related Topics 3
J Verifying the Effectiveness of Corrective Action - Challenge with an external auditor Nonconformance and Corrective Action 16
D Difficult Inspection Level/AQL - Verifying it is the correct part AQL - Acceptable Quality Level 5
N Sampling Plan for Verifying Inventory Status Inspection, Prints (Drawings), Testing, Sampling and Related Topics 3
A Different Methodologies for Verifying Legal Compliance Under ISO 22000:2005 Food Safety - ISO 22000, HACCP (21 CFR 120) 5
T Calibrating or Verifying Metal or Steel Tape Measures General Measurement Device and Calibration Topics 195
B Are there any guidelines / procedures / books to verifying a new equipment? Manufacturing and Related Processes 1
P Verifying Applied Torque General Measurement Device and Calibration Topics 11
P Verifying improvement results - Indication that controls have worked Statistical Analysis Tools, Techniques and SPC 5
C Need help verifying certification for 3000 psi pressure gauge General Measurement Device and Calibration Topics 3
C I need help verifying formula's in a database for LCL UCL Cp Cpk PPk Statistical Analysis Tools, Techniques and SPC 14
B Verifying Accuracy Automated Measurement Device - Width of a strip of steel Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 10
I Verifying our process to approve suppliers for indirect material Supplier Quality Assurance and other Supplier Issues 2
T Closing Out Corrective Actions and Verifying their Effectiveness ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 29
S Corrective Actions - Specifically closing out and verifying effectiveness Nonconformance and Corrective Action 30
lanley liao Question regarding the calibration of monitoring and measure equipment. Oil and Gas Industry Standards and Regulations 0
N IATF Calibration Lean in Manufacturing and Service Industries 3
Q Do these certificates of calibration meet ISO 9001 requirements for traceability to NIST? ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 10
T Plug Gage Calibration Calibration and Metrology Software and Hardware 1
M Load Cell Calibration using a totalizer on a flow meter General Measurement Device and Calibration Topics 0
E Calibration Records needed ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 1
D Limited Range Calibration - 5000 lb Industrial floor scale General Measurement Device and Calibration Topics 3
D Calibration of Small Scales General Measurement Device and Calibration Topics 26
C How to Establish the Calibration & Measurement Capability (CMC)? ISO 17025 related Discussions 1
I IQOQ or just initial calibration required? General Measurement Device and Calibration Topics 3
B Calibration in real life ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 3
J Calibration cycle for monitoring & measuring tools used in medical device manufacturing General Measurement Device and Calibration Topics 5
A Is calibration of test weight required General Measurement Device and Calibration Topics 4
S Calibration Frequency for Slip Gauge Kit used for CMM Calibration? General Measurement Device and Calibration Topics 0
S Calibration/Verification of customer fixtures IATF 16949 - Automotive Quality Systems Standard 6
Ron Rompen Calibration by manufacturer ISO 17025 related Discussions 4
Q Calibration verification records 7.1.5.2.1 IATF 16949 - Automotive Quality Systems Standard 2
B AS9100D 7.1.5.2 Calibration or Verification Method using outside cal lab AS9100, IAQG, NADCAP and Aerospace related Standards and Requirements 1
W Next Calibration Due Date Calibration Frequency (Interval) 5
S Where do l get calibration standards to run a calibration lab? Other ISO and International Standards and European Regulations 2
A OEM On-Site Calibration issues during Covid19 ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 12
D Calibration tolerance question using Pipettes Medical Device and FDA Regulations and Standards News 1

Similar threads

Top Bottom