Abstract
Improper selection and sizing of hydraulic control valves at the preliminary design stage may cause many technical problems. Hydraulic control valves vary in arrangement and complexity depending on their function. The roots of the valve selection dilemma lie in the extraordinary variety of valve designs and the multidisciplinary skills required in selecting proper valves for control applications. Due to lack of complete information, uncertainty, and imprecision for system selection, a technique to perform design calculations on imprecise representations of parameters is presented in this work. This technique is based on fuzzy logic using fuzzy sets. Hydraulic directional control valve alternatives are expressed in terms of fuzzy orders of magnitude. Calculations based on fuzzy weighted average are performed to produce the ratings among design alternatives. Membership functions for the alternative rating are presented for comparison.