Since many valves are used, pressure loss is large, resulting in low reliability of a pump. Even when the period of increasing and decreasing the volume of a pump chamber is long, and a piezoelectric element is used as an actuator that drives a diaphragm, a driving operation cannot be performed at a...http://www.google.com.au/patents/US6623256?utm_source=gb-gplus-sharePatent US6623256 - Pump with inertance value of the entrance passage being smaller than an inertance value of the exit passage
