Siemens SIPART PS2 6DR5020 Series Manual page 19

SIPART PS2 Manual
A5E00074631-01
The exhaust air output E can be provided for supplying dry instrument
air to the tapping chamber and spring chamber to prevent corrosion.
Figure 2-5, page 20 shows the pneumatic connection variants for the
different actuator types, the positioning action and the safety position
after power failure.
Design and Functional Principle
19