Specifications

WESTLOCK CONTROLS CORPORATION
280 MIDLAND AVENUE, SADDLE BROOK, NJ 07663 TEL: [phone] FAX: [phone]
www.westlockcontrols.com
1/12/10 TECH-439/D.W.O. 19024 Page 21 of 58
3.5 Pneumatic Connection
Single Acting Actuator (Spring Return):
For single acting actuators Outlet Port 2 is to be plugged. Outlet Port 1 is to be piped to
the actuator inlet port that acts against the spring. (increasing set-point signal causes
pressure to increase in Outlet Port 1 of the positioner).
Double Acting Actuator (Double Return):
For double acting actuators Outlet Port 2 is piped to drive the actuator towards the fail
position. Outlet Port 1 is piped to drive the actuator away from the fail position.
(increasing set-point signal causes pressure to increase in Outlet Port 1 of the
positioner and pressure to decrease in Outlet Port 2 of the positioner).
Note: Air supply to the positioner must be clean, dry, oil free instrument air per ISA-
S7.3. Maximum supply pressure is 120 psi. All pneumatic connections are 1/4” NPT.
1. Single Acting/Spring Return (Plug Outlet Port 2) increasing signal causes pressure to
increase in Outlet Port 1.
2. Double Acting/Double Return (Pipe Outlet Port 2 to drive actuator towards the
desired failure direction) increasing signal causes pressure to decrease in Outlet Port
2 and pressure to increase in Outlet Port 1.
Notes:
1. On loss of electrical power Outlet Port 1 has zero pressure and Outlet Port 2 has full
pressure.
Figure 3-11