Burkert Type 2012 - Manual (Page 19)

19
Conversionofcontrolfunction
Type 2000, 2002, 2012
7 conveRsion of conTRol funcTion
7.1 description of the functions
Depending on the version, the seat of the valve is closed with or against the medium flow. Spring force (CFA) or
pneumatic control pressure (CFB and CFI) generate the closing force on the swivel plate. The force is transferred
via a spindle which is connected to the actuator piston.
The exact description of the control functions can be found in the operating manual for Type 2000 under:
www.burkert.com .
7.1.1 control function a (cfa)
In rest position, the valve is closed by spring force. By pressurizing the lower control connection, the seal is lifted
from the seat and the flow-through is enabled. The open status is displayed by a position indicator located in the
cover of the actuator.
7.1.2 control function B (cfB)
When not under pressure, the valve is opened by the spring force acting under the piston. By pressurizing the
upper control connection, the valve is closed by the control pressure acting on the piston.
7.1.3 control function i (cfi)
The device operates without spring force. Here, the piston is pressurized alternately, namely at the lower control
connection for opening and at the upper one for closing the valve.
7.1.4 flow below the seat
Depending on the version, the valve is closed against the medium flow by spring force (control function A, CFA) or
by control pressure (control function B, CFB).
As the medium pressure is under the swivel plate, this pressure contributes to the opening of the valve
CFA/CFI CFB/CFI
Figure 5: Flow below the seat (closing against medium)
english