Products

Common Methods of Thermocouple Calibration

UKAS Accredited Thermocouple and RTD Pt100 Calibration

Thermocouples are widely used in industrial and scientific applications to measure temperature. However, whilst thermocouples are robust temperature sensors that cover a wide temperature range, the voltage they generate can be prone to drift over time and through exposure to certain atmospheres. Because thermocouples and associated equipment are usually critical to the processes they monitor, regular calibration, where the thermocouple's output is compared to a known reference temperature and making necessary adjustments, is recommended to monitor any potential drift and to ensure the continued efficacy of the sensor. For some applications, for example those that see a large cycling of temperatures, calibration should be performed frequently.

Why calibrate thermocouples?

Calibrating a thermocouple probe is essential for several reasons:

  1. Accuracy: Over time, thermocouples can drift and lose their accuracy. Regular calibration helps to maintain the precision of temperature measurements.

  2. Quality Control: Many industrial processes rely on precise temperature control. Calibration ensures that the thermocouples used in these processes provide accurate data.

  3. Compliance: In some industries, regulatory standards require specific periodic calibration to maintain compliance with quality and safety standards.

  4. Preventing Errors: Incorrect temperature measurements can lead to costly errors and product defects. Calibration can help prevent these issues.

What is thermocouple calibration?

A thermocouple is a simple but reliable device widely used for temperature measurement in industrial and scientific applications. Thermocouples produce a voltage corresponding to a difference in temperature between a measuring junction and a reference junction. The process of thermocouple calibration involves comparing the thermocouple output measurement against a known reference standard at a known temperature.

A thermocouple calibrator usually refers to a device that simulates a thermocouple voltage. Thermocouple calibrators are used to calibrate thermocouple instruments, transmitters and data acquisition equipment. In this article, we are concerned mainly with the calibration of the thermocouple probe / sensor rather than instrumentation, although we do offer accurate instrument calibration and system calibrations (probe and instrument together) in our laboratory.

How to calibrate a thermocouple probe

There are a few ways to calibrate a thermocouple probe. The most accurate thermocouple calibration is achieved is by using a Fixed Point cell where the thermocouple's output is measured against a number of fixed points along the International Temperature Scale developed in 1990 ITS-90 at the fixed point transition of various metals along the scale. Whilst this is the most accurate method of calibration, the temperatures are not always convenient or useful in practical terms for the intended use of the thermocouple. For example, the melting point of gallium is 29.7646 °C which is not a temperature most thermocouples will be used at. However, the triple point of water (0.01ºC) is used quite regularly in our laboratory.

By far the most popular type of calibration procedure our lab technicians perform is the comparison method where the test sensor is placed in a stirred liquid bath, furnace / oven or dry block calibrators at a specified temperature and it's output is compared against a known reference thermocouple or RTD Pt100 thermometer placed alongside the test thermocouple in the chamber. The sensor can thus be calibrated at virtually any temperature required. Our laboratory can calibrate sensors from liquid nitrogen right up to 1590 degrees celsius as shown in the measurement uncertainty data below.

How often should I calibrate my thermocouple?

The biggest problem for a thermocouple is drift which is caused by temperature cycling and environmental conditions causing contamination. The amount of cycling and contamination will depend on the application. In practice, we would suggest that thermocouple calibration is performed once a year although this should be reduced for thermocouples in use in arduous conditions. Our experienced engineers are available to offer advice either by phone, email or using Live Chat.

What are the risks of not calibrating a thermocouple?

As mentioned above, thermocouples drift over time leading to measurement errors and without regular calibration they may give a reading that is either a bit higher or lower than the actual temperature and so lead to measurement inaccuracy. Having a calibrated thermocouple means that instrumentation can be offset according to the calibration results.

Can thermocouple wire be calibrated?

Yes, if you are making simple thermocouples from a reel of thermocouple wire, then we can issue a calibration for the reel of thermocouple cable used.

Specialists in Thermocouple and RTD (Pt100) Calibration

TC Ltd specialise in thermocouple calibration and RTD calibration and we are proud to offer a wide variety of industry sectors with accurate and traceable In-House or UKAS (United Kingdom Accreditation Service) accredited calibration. This service is applicable for thermocouples, RTD sensors, instrumentation and cables under the scope of ISO/IEC 17025 & ISO 9001, all within our fully UKAS accredited calibration laboratory.

With the drive towards higher product quality standards and energy efficiency, end users are demanding more certainty and traceability from the products they purchase. A speedy, economical and reliable calibration service is provided in all respects. Significant investment has resulted in our UKAS accredited laboratory offering a world class service in terms of both CMC (Calibration and Measurement Capability) and volume throughput.

For more information on thermocouple and RTD calibration, please contact one of our experienced engineers on 01895 252222 or by using the Live Chat.

thermocouple calibration laboratory in action

UKAS or Traceable In-House Certification of Thermocouples and RTD Sensors

Traceable In-house or UKAS accredited calibration is available for Base and Noble metal thermocouples and RTD sensors (Pt100) performed within our fully accredited laboratory.

Calibration is usually by comparison, traceable to National Physical Laboratory primary standards, against SPRTs or Type R reference thermocouples from -100 to +1590ºC. Fixed point calibration also available at -196ºC.

Measurement Uncertainty Data for Thermocouple Calibration and RTD Calibration

Our uncertainty of measurement is listed below for various ranges for thermocouples and RTD sensors:

Type of Sensor

Range Calibration and Measurement Capability (CMC) Expressed as an Expanded Uncertainty
Resistance Thermometers Liquid nitrogen (-196ºC)
Triple point of water (0.01ºC)
-100ºC to -30ºC
-30ºC to + 20ºC
20ºC to 90ºC
90ºC to 200ºC
200ºC to 400ºC
400ºC to 620ºC
0.2ºC
0.050ºC
0.60ºC
0.20ºC
0.20ºC
0.20ºC
0.40ºC
0.40ºC
Thermocouples -
Noble Metal
20ºC to 200ºC
200ºC to 400ºC
400ºC to 620ºC
620ºC to 1100ºC
1100ºC to 1200ºC
1200ºC to 1330C
1330ºC to 1590ºC
0.90ºC
0.90ºC
0.90ºC
1.70ºC
1.70ºC
2.70ºC
3.30ºC
Thermocouples -
Base Metal
Liquid nitrogen (-196ºC)
-100ºC to -30ºC
-30ºC to + 200ºC
200ºC to 400ºC
400ºC to 620ºC
620ºC to 1100ºC
1100ºC to 1200ºC
1200ºC to 1330ºC

0.35ºC
0.60ºC
0.30ºC
0.50ºC
0.60ºC
1.80ºC
1.80ºC

2.60ºC



International and Industry Specific Standards

Calibration can be performed to meet the requirements of most international and industry specific standards including AMS2750G, IEC 60584-1, IEC 60571, ASTM E220, ANSI MC 96.1, ASTM E235, ASTM E608, ASTM E839, GDCD16 & BAC5621K. We can also perform batch and reel calibration on selected material to ensure the best results possible when adhering to these strict standards.

Other Calibration

Electrical simulation for precision instrumentation calibration. Surface measurement is also available as well as calibration of sensors and instrumentation together as a system.

International Calibration Bodies

NPL is a signatory to the CIPM MRA (Mutual Recognition Agreement) and as such results shown on our certificates can be considered as being traceable to all other NMIs (National Measurement Institutes) who are signatories to the MRA including NIST.

Conclusion

Thermocouple calibration is a crucial step in ensuring accurate temperature measurements in various applications. Regular calibration helps maintain the reliability and precision of thermocouples, reducing the risk of errors and improving product quality. By following the appropriate calibration methods and documenting the process, you can ensure that your thermocouples provide consistent and accurate temperature data.

For more information on thermocouple and RTD calibration, please contact one of our experienced engineers on 01895 252222 or by using the Live Chat.

thermocouples being calibrated in a furnace

Enquiry Form

1. Type of Calibration

2. Number of Sensors

3. Calibration Points Required

4. Type of Sensor

4a. Sensor diameter (optional)

4b. Sensor Length (optional)

Contact Details

Company Name


Your Name


Title/Dept.


Email


Telephone


Additional Information

If your enquiry is for more than one style of sensor, please email us with your requirements or use the box below



Send Enquiry  

We will only use your email address to contact you. We will never give your email address to 3rd parties and we do not sell data on to any other company. We prefer to concentrate on making quality temperature related products. Our privacy policy can be viewed here.

BACK TO TOP
Products

Contact Us

About TC

FREE Guide

Privacy Policy

Terms and Conditions

Sitemap
FREE Wallchart Guide to
Thermocouples and RTD Sensors


Join over 500,000 engineers and buyers who have already received our FREE 74 page A3 Guide to Thermocouple and Resistance Thermometry

Company Name
  Address 1
Your Name
  Address 2
Title / Dept.
  County / Region / State
Email
  Postcode / ZIP Code
Telephone
  Country
Company Name
Your Name
Title / Dept.
Address 1
Address 2
County / Region / State
Postcode / ZIPCode
Country
Email
Telephone

We will only ever use the information you provide to occasionally contact you regarding our products and we will never disclose your details to a third party. Please see our privacy policy for more details.



I agree to the terms and conditions listed in the Privacy Policy

View our ISO 90001/2008 Certficate recycle products EHS Policy
View our ISO 90001/2008 Certficate

recycle products

EHS Policy



Thermocouple Sensors
Mineral Insulated Thermocouples
Thermocouples with Mini Plug
Thermocouples with Terminal Head
Thermocouples with Cable
High Temperature Thermocouples
General Purpose Thermocouples
ATEX/IECex Thermocouple Sensors
Ceramic Thermocouple Sensors
Fast Response Thermocouple Sensors
Autoclave Thermocouple Sensors
Surface Measurement Thermocouple Sensors
FEP Insulated Thermocouple

Platinum Resistance Thermometers
Mineral Insulated RTD Pt100 Sensors
Rigid Stem RTD Pt100 Sensors
Hand Held RTD Pt100 Sensors
Surface Measurement RTD Pt100 Sensors
RTD Pt100 Sensors with Cable
RTD Pt100 Sensors with Mini Plug
Autoclave RTD Pt100 Sensors
RTD Pt100 with Terminal Head
ATEX/IECex Platinum Resistance Thermometers
Fast Response RTD Pt100 Sensors
Air Temperature RTD Pt100 Sensors
Magnetic RTD Pt100 Sensors
Cable
PVC Single Pair Thermocouple Cable
PFA Single Pair Thermocouple Cable
Fibreglass Single Pair Thermocouple Cable
PVC Multipair Thermocouple Cable
PFA Multipair Thermocouple Cable
Fibreglass Multipair Thermocouple Cable
PVC RTD Pt100 Cable
PFA RTD Pt100 Cable
Fibreglass RTD Pt100 Cable

Miniature Thermocouple Connectors
Mini Thermocouple Connectors – 220ºC Rated
Mini Thermocouple Connectors – 350ºC Rated
Mini Thermocouple Connectors – 650ºC Rated
Mini Thermocouple Connector Accessories
Mini Thermocouple Connector Panels
Mini Three Pin Connectors

Standard Thermocouple Connectors
Standard Thermocouple Connectors – 220ºC
Standard Thermocouple Connectors – 350ºC Rated
Standard Thermocouple Connectors – 650ºC Rated
Standard Thermocouple Connector Accessories
Standard Thermocouple Connector Panels
Standard Three Pin Connectors
Instrumentation
Hand Held Indicators
Panel Indicators
Temperature Transmitters
Temperature Controllers
Temperature Programmers
Temperature Calibrators
Chart Recorders
Multi Channel Indicator
DIN Rail Mounted Transmitters
Head Mounted Transmitters
ATEX/IECEx Rated Transmitters
Dry Block Calibrator
Temperature Dataloggers

Temperature Accessories
Compression Fittings
Pressure and Vacuum Feedthroughs
ATEX/IECEx Compression Fittings

Calibration
UKAS Calibration Services

Pressure
Pressure Gauges
Pressure Transmitters


© 1998- TC Ltd., P.O. Box 130, UXBRIDGE, UB8 2YS, United Kingdom
Tel.: 01895 252222, Email: info@tc.co.uk
© 1998- TC Ltd., P.O. Box 130, UXBRIDGE, UB8 2YS, United Kingdom
Tel.: 01895252222, Email: info@tc.co.uk