Avid Technology SMARTCAL - Pneumatic Connection

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12/17/12 TECH-440/D.W.O. 23135 Page 18 of 55
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 or 1/4 BSP.
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 3-9