Based on international standard, protection type solenoid valve and flameproof type solenoid valve of our company apply the requirements for NAMUR and in- line (pipe) connection and can be adapted for 3/2 NC or 5/2 functions for controlling double-acting and single-acting pneumatic actuators without any adaptor. And spool valves comprise a manual override providing
operation without electrical supply. The valve is a real multifunctional solenoid valve. Armed with “environmentally-protected structure”，all the exhaust ports of this spool valve are connectable which offer excellent environmental protection against the ingress of liquids, dusts or other foreign
matter. Working pressure from 1bar to 8bar (Aluminum) or 1. 5bar to 8bar (SS316L) and the working voltage from 12 -48VDC，110- 240VAC.

According to the NAMUR international standard, the POT board-mounted solenoid valve POT521 / 321 can be directly
installed in the air source interface (or pipe connection) of the pneumatic actuator to implement the switching control of
the pneumatic actuator / valve. Air source working pressure 1-8bar, power supply voltage 12-48VDC, 110-240VAC.
POT521 is 5/2 for Double acting type Pneumatic actuator.
POT321 is 3/2 for Single acting type Pneumatic actuator.