The vitamin C powder on the test sieve keeps moving with the vibration of the sieve. The fine powder continuously passes through the sieve, but the large particles cannot pass through the sieve, thereby achieving the separation of large particles and small particles and achieving the screening pass rate test. the goal of. After screening for a certain period of time, weigh the mass of the objects on the sieve, and divide the difference between the mass of the objects on the sieve and the mass before screening by the total mass before screening to obtain the pass rate. Normally, the screening pass rate of vitamin C powder will gradually stabilize as the number of repetitions increases or the screening time prolongs.