ASTM D4584-05 (2022) Standard test method for the measurement of apparent pH value in electrical coating tanks specifies the standard test method for measuring the apparent pH value of solutions in electrical coating tanks. This method is mainly used in the electro-coating process. The pH value of the electrolysis liquid in the electric coating tank is measured to monitor the alkaline, thereby ensuring the Stability and mass of the coating process. The standard details the selection of instruments, measurement procedures and operating requirements to ensure the accuracy and Repeatability of the measurement results. This test is of great significance for adjusting the chemical environment in the painting process, optimizing the coating mass and prolonging the service life of the electric coating tank.