Spirax Sarco SP8-10, Installation And Maintenance Instructions Manual

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IM-P707-01 CTLS Issue 1
35
SP8-10 Smart positioner
Information on double acting actuators with spring-return mechanism
On double-acting actuators with spring-return mechanism, a pressure that significantly exceeds the supply
air pressure value can be generated during operation by the springs in the chamber opposite the springs.
This may damage the positioner or adversely affect control of the actuator.
To eliminate the possibility of this occurring, it is recommended to install a pressure compensation valve
between the spring less chamber and the supply air for these types of applications. It enables the increased
pressure to be transferred back to the air inlet line.
The opening pressure of the check valve should be < 250 mbar (< 3.6 psi).
Fig.23
Marking Pipe connection
IN Supply air, pressure 1.4 to 10 bar (20 to 145 psi)
OUT1 Output pressure to the actuator
OUT2 Output pressure to the actuator (2. Connection with double acting actuator)
Join the pipe connections according to the designation, observing the following points:
-
All pneumatic piping connections are located on the right-hand side of the positioner. ¼ 18 NPT tapped
holes are provided for the pneumatic connections. The positioner is labeled according to the tap holes
available.
-
We recommend that you use a pipe with dimensions of 12 × 1.75 mm.
-
The supply air pressure required to apply the actuating force must be adjusted in line with the output
pressure in the actuator. The operating range of the positioner is between 1.4 to 6 bar (20 to 90 psi)***.
(1) OUT 2
(2) OUT 1