Why should the accuracy of a master instrument be 4 times than the device under calibration?

Instrument_Engineer · January 10, 2024, 4:58pm

The necessity for precise and reliable measurements in a variety of industries is the reason behind the requirement that the master instrument have an accuracy four times higher than the device being calibrated.
The concept is in keeping with established procedures and standards supplied by organizations such as the National Institute of Standards and Technology (NIST) and the International Organization for Standardization (ISO), even though there may not be a global standard requiring this specific ratio.
Accurate measurements are essential in a variety of industries, including research and development, manufacturing, and healthcare.
An instrument’s accuracy is determined by how well it can produce results that are near to the true or reference value.
Ensuring the accuracy of measurements requires calibration, which is the act of adjusting an instrument to match its readings with a recognized standard.
Although not commonly instructed, the 4:1 ratio is considered a safe calibration technique.
This ratio acts as a safety support, allowing for fluctuations, uncertainties, and possible errors in the calibration equipment as well as the master instrument.
There is a higher likelihood of inaccuracy in the calibration process if the master instrument is only marginally more accurate than the device being calibrated.
Having a master instrument with a much better accuracy reduces errors and uncertainties in precision measurement conditions.
This is especially crucial in highly sensitive sectors where accuracy is essential, such semiconductor production, medical equipment, and aerospace technology, where the calibrated instrument is used.
In addition, companies can use the 4:1 ratio into their quality management systems to meet ISO requirements, such ISO/IEC 17025 for calibration laboratories or ISO 9001 for quality management.
These standards support the general quality of goods and services by highlighting the significance of measuring consistency, traceability, and reliability.
In order to ensure that the calibration process satisfies the necessary accuracy criteria, calibration laboratories frequently adhere to particular protocols and recommendations.
Leading metrology organization NIST offers traceable standards and recommendations that impact calibration lab best practices around the world.
In addition to being a theoretical suggestion, the idea of a master instrument with greater accuracy serving as a reference has real-world applications for getting accurate measurements.
It is helpful to take into consideration factors that can change an instrument’s accuracy over time, such as manufacturing process variations, weather conditions, and instrument wear and tear.
In summary, even though a strict international standard defining a 4:1 ratio may not exist, the idea of using a master instrument that is noticeably more accurate than the device being calibrated is generally accepted and adhered to in the search for measurement reliability and accuracy.
This procedure is based on the overriding objective of delivering precise and consistent outcomes in a variety of industries, protecting the integrity of industrial processes, scientific research, and other applications where accuracy is critical.