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When comparing the old and new standards, the main differences are as follows: (1) The new national standard adds a \"service life\" parameter, bringing the total number of performance indicators to 14: 1 basic error； 2-cycle difference ； 3 Dead Zone ； 4 Constant point deviation ； 5 Rated stroke deviation ； 6 Leakage amount ； 7 Sealing performance of the stuffing box and other connections: 8 Sealing performance of the air chamber ； 9 Voltage withstanding strength ； 10 Rated flow coefficient ； 11 Inherent flow characteristics ； 12 Vibration resistance ； 13 Action Life Span ； 14 Appearance. (2) The new national standard classifies basic error, hysteresis, dead zone, constant position deviation, and rated stroke deviation into 8 grades: A, B, …… H, so as to select the grade with the best performance-cost ratio based on the different functional requirements of various valves. The old standard assigned a unique index to each type of valve, lacking flexibility. (3) The new national standard classifies leakage amounts into A, B… F – these 6 levels, with the highest level, F, being determined by the number of bubbles per minute. The old standard had only one grade, and requiring a leakage rate of 0 for high-pressure valves was not practical. (4) Flow characteristic error testing method: The new national standard adds a method for testing using the slope approach. (5) The new national standard replaces the term \"circulation capacity\" in the old standard with \"flow coefficient\". The values were uniformly specified under the old standards, while the new national standards allow manufacturers to determine them on their own, which facilitates the design and finalization of new products. (6) The number of test points for basic error and hysteresis has been changed from 10 according to the old standard to 5. (7) Requirements of the new national standard for the air supply and ambient temperature of control valves. The air source should be clean and dry, free of significant corrosive gases, solvents, or other liquids. For control valves equipped with positioners, the amount of solid particles in the air supply should be less than 0.1 g/m3; the diameter of these particles should be greater than 3 μm, and the oil content should be less than 1 ppm. The ambient temperature for the control valve is -25 to +55°C or -40 to +70°C. The control valve must meet the above requirements when in operation. An unclean air supply for the locator is the main cause of abnormal operation of the locator, accounting for over 2/3 of all failures; special attention should be paid to this issue.