Pneumatics

An I/P module with subsequent pneumatic amplifier is used to

control the pneumatic actuator. The well-proven I/P module

proportionally converts the permanent electrical setpoint signal

from the CPU into a pneumatic signal used to adjust a 3/3 way valve.

The air flow for pressurizing or depressurizing the actuator is

continuously adjusted. As a result, excellent control is

achieved. When reaching the setpoint, the 3/3-way valve is

closed in center position to minimize the air consumption.

Four different pneumatics versions are available: for single

acting or double-acting actuators, each with “fail-safe” or “fail freeze” function.

“Fail-safe” function

If the electrical supply power fails, the positioner output 1 is

depressurized, and the pneumatic actuator’s return spring

moves the valve to the defined safe position. In case of a

double-acting actuator the second output 2 is additionally pressurized.

Change from two to one column

“Fail-freeze” function

If the electrical supply power fails, the positioner output 1 (and

2. if applicable) is closed and the pneumatic actuator stops

(“freezes”) the valve in the current position. If the compressed

air supply power fails, the positioner depressurizes the actuator.