Temperature measurement is important in many industries, such as manufacturing, pharmaceuticals, food processing and energy production. Temperature calibration is one of the most essential processes that maintains accuracy in temperature measurement and ensures that instruments provide precise and reliable data over the years.
In this blog, we discuss everything you need to know about temperature calibration, its significance, procedures, calibration ranges, and industry standards.
What is Temperature Transmitter Calibration?
Temperature transmitter calibration is the process of checking and adjusting a temperature transmitter to ensure its reading accurately reflects the actual temperature being measured. A temperature transmitter converts the signal of a sensor (such as an RTD or thermocouple) into a standard output signal, usually 4-20 mA.
In the long run, factors such as environmental conditions, ageing components, and mechanical stress may affect the accuracy of these devices. Calibration ensures that the transmitter continues to function within acceptable limits and meets operational standards.
Importance of Calibration of Temperature Measuring Instruments
The calibration of temperature measuring instruments is essential due to a number of reasons:
- Ensures precise temperature readings, thereby minimising the risk of faulty processes.
- Most industries have stringent safety standards that require accurate temperature control.
- Ensures consistent product quality, particularly in sectors such as pharmaceutical and food processing.
- Helps meet national and international calibration requirements.
- Eliminates mistakes which may lead to wastage, rework, or equipment damage.
Calibration Procedure for Temperature Transmitter
The calibration procedure for a temperature transmitter is normally done in the following steps:
- Gather the required equipment, including a calibrator, a reference thermometer, a power supply, and a communication device. Isolate the transmitter from the process.
- Check for any physical damage, loose connections, or wiring issues.
- Next, enter a known temperature with a calibrator or dry block calibrator.
- Measure the transmitter’s output signal and compare it to the desired value.
- In case of discrepancies, adjust transmitter output with calibration tools or software.
- Do the same for several points to ensure you get accurate results across the range.
- Lastly, record the outcome on a temperature calibration graph for future use and compliance.
- How to Calibrate a Temperature Transmitter Using a HART Communicator
- A HART (Highway Addressable Remote Transducer) communicator enables technicians to programme and calibrate smart transmitters digitally.
The process includes:
- Attach the HART communicator to the transmitter loop.
- Viewing calibration settings using the interface.
- Entering reference values.
- Digitally adjusting zero and span values.
- Checking the accuracy of the output signal.
Temperature Transmitter Calibration Range Explained
The temperature transmitter calibration range refers to the lowest and the highest temperature values within which the transmitter is calibrated and expected to perform accurately.
For example:
The transmitter can be calibrated between 0 and 100 degrees Celsius. Another may work between -50 and 300 degrees Celsius.
Calibration is generally performed at various points within this range (e.g., 0%, 25%, 50%, 75%, and 100%). It is essential to maintain accuracy across the entire range for a reliable performance.
Temperature Sensor Calibration and Its Role
The calibration of temperature sensors is closely linked with transmitter calibration. As the transmitter is dependent on the sensor input, any error in the sensor will have a direct impact on the output.
The types of common temperature sensors are the following:
- Resistance Temperature Detectors (RTDs)
- Thermocouples
- Infrared (IR) sensors
Temperature Meter Calibration Process
The temperature meter calibration process ensures that the temperature indicators and display units give accurate readings.
Steps typically include:
- Connecting the meter to a known temperature source.
- Comparing the readings displayed with reference values.
- Adjusting the meter to match the standard.
- Recording results in a calibration report
Temperature Calibration Standards and Guidelines
Compliance with temperature calibration standards guarantees consistency and reliability across industries.
The commonly known standards are:
- Guidelines by ISO (International Organisation for Standardisation)
- IEC (International Electrotechnical Commission) standards
- Standards defined by the national calibration laboratory.
Furthermore, deviations and compliance are tracked using tools such as the temperature calibration chart.
Other related procedures are:
- Temperature indicator calibration for display units.
- Temperature switch calibration refers to the calibration of safety systems which are activated when the temperature reaches certain levels.
- Dry-block calibration for industrial field testing
At a Glance
Temperature transmitter calibration is an important process that ensures accurate temperature measurement across various industrial applications. With their focus on regular calibration and maintenance, industries can reduce mistakes, enhance performance and guarantee long-term success.
