What are the different methods of instrument calibration?

Instrument calibration is a crucial process in ensuring the performance, efficiency, and safety of equipment. The accuracy of all measuring devices and instruments degrades over time. This creates what is known as ‘measurement drift’ - a growing level of inaccuracy which needs to be addressed by periodic recalibration. Organisations must meet recognised international calibration standards when recalibrating equipment.

Each industry utilises different engineering and manufacturing methods, which in turn requires different methods of instrument calibration. So, what are some of the most common methods of instrument calibration, and what are the compliance standards that manufacturers have to adhere to for each?

Mechanical calibration

Mechanical calibration encompasses a range of different equipment and calibration methods. The instruments that require mechanical calibration are those which measure physical forces, parameters and elements. As each instrument varies in how they measure, specific calibration methods are required.

Pressure

Pressure calibration plays a vital role in ensuring safety and precision for a wide range of appliances and equipment. Pressure readings are used to identify features in chemical reactions, predict weather by measuring barometric pressure, and are used by customers in a range of devices. Specific examples of pressure based instruments include:

Pressure gauges
Barometers
Pressure transducers

Pressure instruments are calibrated by recording the measurement of a device under test (DUT) and comparing it to a reference standard, which is an accurate pressure reading device. The DUT is then calibrated to match the reference standard. An ISO/IEC 17025 accreditation is given to businesses that are within regulatory compliance to provide pressure as well as other calibration services.

Temperature

Temperature measurement needs to be precise and reliable for a range of engineering and manufacturing applications. Industrial thermometers require accuracies ranging from 5 °C to 0.5 °C to maintain efficiency, whereas laboratory environments require sensitive standard platinum resistance thermometers (SPRT) that provide accuracies from 0.5 °C to 0.02 °C. Further examples of temperature measuring instruments include:

Infrared metres
Furnaces
Thermal cameras

Temperature calibration is based on a sourcing temperature, which is either simulated using an electronic device or created under a controlled environment using dedicated furnaces, IR calibrators for temperature chambers. The DUT is then calibrated to these precise and controlled temperature sources in compliance with The International Temperature Scale of 1990 and ISO 9001:2015.

Dimensional

Dimensional precision is the foundation of architecture, engineering, and almost every other manufacturing environment; without the correct dimensional calibration, entire projects would fall apart from the ground up. Dimensional instruments are used to measure length, width and mass, and demand exact precision. Examples of these instruments include:

Verniers
Micrometres
Taper Gauges

Dimensional calibration involves the comparison of a specific instrument to an applicable measurement standard. ISO 17.020 - 17.040 includes the international standards for the various dimensional calibrations. Instruments must be calibrated in compliance with these standards so that the process from design to manufacture or construction can be a seamless one.

Torque

Torque measurement is extremely important to automotive industries to ensure peak performance and international compliance. Precise torque measuring instruments are vital in the research, inspection and production stages of these industries; Examples include:

Torque gauge
Torque metre
Torque sensor

British standard 7882:2008 provides an agreed method of utilising a calibration beam to calibrate torque instruments within the UK. Instruments are rotated around the beam through a set series of torques in four different mounting positions to get an accurate calibration. BS 7882:2008 also provides standardised environment and temperature conditions(within the range 18°C to 28°C) for the tests to ensure precision of the results.

Electrical calibration

A wide range of industries depend on electrical test instruments to maintain the safety and quality of their devices. Ineffective test instruments can directly result in product defects, equipment failures and health risks to individuals. Electrical calibration is required to ensure the quality of test apparatus across all major parameters.

Electronic calibration is performed by using a precise device that evaluates the performance of a unit under test (UUT) based on specific electrical parameters, such as voltage or resistance. The precise device is regularly calibrated in compliance with international and regional standards of the specific parameter being tested, ensuring accuracy and compliance. These standards include:

Voltage standards
AC/DC transfer standards
AC measurement standards
Resistance standards
Ratio standards
Current shunts

Keeping your instruments calibrated and compliant

Ensuring your test equipment is accurately calibrated and reliable is a necessary process in any industry. Not only does it avoid manufacturing defects and safety risks, but ensures you are compliant with international standards and regulations.

At DM Systems & Test, our calibration solutions are certified by the United Kingdom Accreditation Services (UKAS) and compliant with ISO 9001:2015. Our expert engineers are trained to calibrate mechanical and electrical equipment used in specialist industries, and our laboratory facilities are state of the art to ensure accuracy and precision.

To learn more about how we can take care of your organisation’s calibration requirements, no matter how complex or what industry you are in, contact our team today.