Description: The ratio of the output variable to the rate of change of the input variable; Name: differential factor
Description: for a derivative element, the quotient of the value of the output variable to the value of the time derivative of the input variable; Name: derivative action coefficient
Description: NPSH-value required for a drop of 3 % in the total head of the first stage of the pump as a standard basis for use in performance curves; Name: Net positive suction head required for a drop of 3 %