Abstract: Counterpoising the problems in the theoretical derivation of conventional flow equation for roatmeter, a new flow equation for rotameter is obtained based on the theoretical derivation. At the mean time, the characteristic curves of for rotameter between the new flow equation and the classical equation are compared in response to calibration data. Through the compare between the classical flow equations and the modified flow equation, the problem of the confounding of physical conception is found and explained. At last, it is pointed out that the new flow equation for rotameter and the classical flow equation for rotameter have the same character in essence.

Key words: Flow equation Characteristic curve of, Rotameter