Working standards in the context of measurement and instrumentation refer to the reference instruments, equipment, or artifacts that are used as the basis for calibrating or verifying other measurement instruments. These standards ensure that measurements taken with various instruments are accurate, consistent, and traceable to a common reference point. Working standards are an essential part of any measurement system to maintain accuracy and reliability.
Here's how working standards typically work in the field of measurement and instrumentation:
Reference for Calibration: Working standards are often highly accurate and stable instruments that have been calibrated by a recognized metrology laboratory or organization. They serve as the primary reference points against which other instruments are calibrated. Calibration involves comparing the measurements of the instrument being calibrated with those of the working standard to determine any discrepancies and adjust the instrument's settings accordingly.
Traceability: Traceability is a crucial concept in measurement. It ensures that measurements can be linked to a known and documented reference. Working standards are traceable to national or international measurement standards through a documented chain of calibrations. This traceability provides confidence in the accuracy of measurements made with instruments that have been calibrated using working standards.
Accuracy and Stability: Working standards are chosen for their high accuracy and stability. They are carefully maintained to ensure that their measurements remain consistent over time. Any changes in their performance are carefully tracked, and adjustments are made as needed to maintain accuracy.
Interlaboratory Comparisons: To establish confidence in the accuracy of working standards, interlaboratory comparisons are often conducted. Different laboratories or organizations with recognized measurement expertise collaborate to compare their working standards' measurements. This helps identify any discrepancies and ensures consistency across different measurement systems.
Calibration Certificates: When an instrument is calibrated using a working standard, a calibration certificate is issued. This certificate documents the comparison between the instrument being calibrated and the working standard, along with any adjustments made. It provides a record of the instrument's accuracy and traceability.
Periodic Recalibration: Working standards themselves need to be recalibrated periodically to maintain their accuracy. The frequency of recalibration depends on the stability of the standard, its intended use, and industry regulations.
Types of Working Standards: There are various types of working standards, including primary standards, secondary standards, and working transfer standards. Primary standards are the highest level of reference and are often maintained by national metrology institutes. Secondary standards are calibrated against primary standards and are used for routine calibrations within calibration laboratories. Working transfer standards are used in various measurement settings and are calibrated against secondary standards.
Working standards play a critical role in ensuring the reliability and consistency of measurements in various fields, including physics, engineering, chemistry, and more. They form the foundation of traceable and accurate measurement systems.