ASCO™ Series 320 Solenoid Valve The ASCO Series 320-s are general-service solenoid valves designed for a broad range of applications. The direct-acting valves are available in voltage-ranging, harsh-environment, direct-mount, dribble-control, and long-life constructions. They are suitable for use in analytical and diagnostic equipment, dust collector systems, life sciences, and press room and metal stamping.