Standard substances are substances that meet the requirements of uniformity and stability, have reliable metrological traceability and uncertainty in their characteristic values, and meet the needs of metrological activities such as metrological traceability, value transfer, and measurement accuracy evaluation.
Function and significance
Value transmission and traceability: As a measurement standard, it ensures the transmission and traceability of characteristic values, ensuring consistency in measurement results between different laboratories.
Evaluation of measurement methods: By comparing with standard substances, evaluate the accuracy and repeatability of the measurement method, verify and improve the measurement method.
Quality control: In collaborative experiments between laboratories, the same standard substance is used to calibrate data and improve the reproducibility of measurement results. At the same time, it is used to create quality control charts to ensure that the measurement results of the inspection work are under quality control.
Technical arbitration and standard setting: When formulating testing methods, standard methods, and product standards, standard substances are used as working standards to obtain reliable data.
Main Categories
According to the type of characteristic values: divided into chemical composition standard substances (such as pure substances, alloy standards), physical characteristic standard substances (such as density, hardness standards), and engineering technical characteristic standard substances (such as particle size, viscosity standards).
According to the fixed value level, it is divided into * * standard substances (used for calibrating secondary standards and high-precision measurements) and secondary standard substances (industry level, used for daily measurement calibration).
By form: including solids (such as metal blocks, powders), liquids (such as standard solutions), and gases (such as standard gas mixtures).
Management and usage precautions
Certificates and Uncertainty: Each standard substance has a corresponding certificate, which provides the standard value and measurement uncertainty of the standard substance.
Validity period and storage: Standard substances have an expiration date, and standard substances that exceed the expiration date may cause a significant increase in uncertainty. Therefore, standard substances should be properly stored according to the requirements and storage conditions specified in the certificate to prevent external contamination.
Usage: When using standard substances, follow the instructions in the certificate to ensure the accuracy and reliability of the measurement results.