The JJF (Petrochemical) 052-2021 film Anti-Sag Meter calibrating specification specifies the calibration method and requirements of film Anti-Sag Meter in detail. The standard is applicable to the calibrating work of film Anti-Sag Meter, the purpose is to ensure the accuracy and reliability of the instrument in the measurement of film Sag phenomenon. The standard specifies the technical requirements of film Anti-Sag Meter, the calibration procedure and the necessary conditions for verification, including the error range of sag measurement, the inspection frequency of the equipment, and the reference standard used in calibrating. By implementing this specification, the measurement accuracy of the equipment can be improved, the repeatability and conformity of the film sagging test results can be ensured, and a reliable basis for film performance evaluation can be provided.