ASTM E220: Thermocouple Comparison Calibration Testing Services
ASTM E220 is used to describe the principle, apparatus, and procedure to calibrate thermocouples by comparing them with a reference thermometer.
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- Overview
- Scope, Applications, and Benefits
- Test Process
- Specifications
- Instrumentation
- Results and Deliverables
What Is ASTM E220 Thermocouple Comparison Calibration?
ASTM E220 specifies a standardized procedure for calibrating unused thermocouples in relation to a reference thermometer. It specifies the procedures for measuring the differences in the electrical potential generated by the thermocouple and the reference standard at a given temperature.
This procedure is applicable to unused thermocouples. It cannot be applied to thermocouples that have already been used because inhomogeneity of the materials may be present and cannot be detected using calibration procedures. When calibrating thermoelements with large diameters and sheathed thermocouples, special attention must be taken to reduce thermal conduction losses.
Applications and Benefits of ASTM E220 Thermocouple Comparison Calibration Testing
Scope
The test specimen is installed between two reverberation rooms, and a diffuse sound field is generated in the source room. Sound energy strikes the specimen, causing it to vibrate and transmit sound into the receiving room. Sound pressure levels are measured in both rooms, and the sound absorption in the receiving room is determined. For improved accuracy, the test may be repeated with the source and receiving rooms reversed, and the results are averaged to obtain the final transmission loss values.
Applications
- Thermocouple manufacturing quality control
- Calibration laboratories
- Industrial temperature measurement systems
- Furnace and heat-treatment process validation
- Power generation industries
- Research and development laboratories
- Metrology and standards verification
Benefits
- Ensures thermocouple accuracy before use
- Provides traceable calibration data
- Detects deviations from standard EMF tables
- Improves measurement reliability
- Supports compliance with quality standards
- Applicable over a wide temperature range
- Offers multiple calibration approaches
Our ASTM E220 Testing Procedure
Measurement Setup
Thermocouples are connected via automated scanning or manual sequence, with reference readings taken for accuracy.
1EMF Measurement
EMF is measured for each thermocouple, or directly as a differential EMF in the differential method.
2Temperature Stabilization
Measurements are repeated at the same stabilized temperature to ensure consistency and minimize variation.
3Data Calculation
ΔE is calculated as Er – E, where Er is the reference EMF and E is the measured EMF.
4ASTM E220 Test Parameters and Requirements
| Parameter | Details |
|---|---|
| Calibration Range | -195°C to 1700°C |
| Applicable Specimens | Unused thermocouples only |
| Measurement Output | Electromotive Force (EMF) deviation |
| Calculation Formula | ΔE = Er – E |
| Reference Requirement | Standard EMF reference tables |
| Limitation | Not applicable to used thermocouples |
- Reference thermometer (meeting required uncertainty)
- Voltmeter (high-precision EMF measurement)
- Scanning unit (for automated method)
- Data acquisition and storage system
- Calibration furnace or temperature source
- Calibrated EMF reference source
- Switching system (manual method)
Equipment and Instrumentation Used for ASTM E220 Testing
What You Receive: Test Report, Data, and Certification
- EMF deviation values at calibration points
- Calibration tables across temperature range
- Measurement uncertainty evaluation
- Compliance verification with reference tables
- Traceable calibration report
ASTM E220 Thermocouple Comparison Calibration FAQs
The ASTM E220 standard calibrates a thermocouple by matching its EMF response with that of a reference sensor at the same temperatures. Such a method of comparison allows for the calibration of a thermocouple at various temperatures within a reasonable testing period.
The comparison medium ensures that both sensors are exposed to the same temperature. Liquid baths reduce temperature gradients at lower to moderate temperatures, while furnaces with equalization blocks are used at higher temperatures.
ASTM E220 is applicable to base metal and noble metal thermocouples over a wide range of temperatures. The type of the reference sensor depends on the temperature range, which ensures accuracy in comparison and reduces the uncertainty of measurement for various thermocouple configurations.
The results of the calibration process include the nominal temperature, reference temperature, and the deviation of the thermocouple. These results are used to determine the correction factors or coefficients that can be used in the instrumentation to improve the accuracy of temperature measurement.
ASTM E220 can be applied across a wide temperature range depending on thermocouple type and comparison medium, allowing accurate calibration from cryogenic temperatures up to high-temperature furnace conditions using appropriate reference sensors.
Why Choose Infinita Lab for Thermocouple Comparison Calibration Testing
At the core of this breadth is our network of 2,000+ accredited laboratories across the USA, offering access to over 10,000 testing methods and analytical services. From advanced materials characterization (SEM, TEM, RBS, XPS) to mechanical, chemical, environmental, biological, and standardized ASTM/ISO-compliant testing, we deliver unmatched flexibility, specialization, and scale. You are never limited by geography, facility, or methodology — Infinita Lab connects you to the right expertise and testing solution, every time.
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