Compressible bench flow adaptations to the experimental characterization of pneumatic fluid power components. Application to the determination of flow-rate characteristics of a Festo MPYE-5-3/8-010-B proportional valve

Abstract

This paper describes the operating and basic characteristics of a general purpose compressible flow bench facility developed to accomplish experimental test in fluid dynamics, as well as the required adaptations according to ISO 6358 for pneumatic fluid power components characterization such as, valves, regulators, filters, filter-regulators, cylinders, ... etc, are described. The experimental characterization of pneumatic fluid power components, espccially proportional valves and servo-valves are required when their performance must be modelled. The technical characteristics from suppliers are, in general, insufficient. The sonic conductance, critica! pressure ratio, coefficient of compressibility effect, and effective area, must be specified according to ISO 6358. In additíon, the corrected mass flow rate as function of the absolute inlet pressure and pressure ratio must be calculated. In this work, the experimental flow-rate characteristics of a Festo MPYE-5-3/8-010-B pnewnatic fluid power proportional valve operating in open-loop circuit control, is obtained. The actual and corrected mass flow rates, sonic conductance and effective area at dífferent absolute inlet pressures versus excitation voltage are shown. The corrected mass flow rate has been obtained in both, with upstream and downstream measuring tubes, and exhausting directly to atrnosphere for different spool positions. This allows to obtain a vei:y useful experimental correlation between effectíve area and excitation voltage. Also the hysteresis effects have been studied. In conclusion, a closed loop circuit control operating is recorrunended, since for high excitation voltage these effects are significant.