22
Conversion of control function
Type 2000, 2002, 2012
9 CONVERSION OF CONTROL FUNCTION
9.1 Description of the functions
Dependingontheversion,theseatofthevalveisclosedwithoragainstthemediumow.Springforce(CFA)
orpneumaticcontrolpressure(CFBandCFI)generatetheclosingforceontheswivelplate.Theforceistrans-
ferred 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.
9.1.1 Control function A (CFA)
Inrestposition,thevalveisclosedbyspringforce.Bypressurizingthelowercontrolconnection,theseal
isliftedfromtheseatandtheow-throughisenabled.Theopenstatusisdisplayedbyapositionindicator
located in the cover of the actuator.
9.1.2 Control function B (CFB)
Whennotunderpressure,thevalveisopenedbythespringforceactingunderthepiston.Bypressurizing
theuppercontrolconnection,thevalveisclosedbythecontrolpressureactingonthepiston.
9.1.3 Control function I (CFI)
Thedeviceoperateswithoutspringforce.Here,thepistonispressurizedalternately,namelyatthelower
controlconnectionforopeningandattheupperoneforclosingthevalve.
9.1.4 Flow below the seat
Dependingontheversion,thevalveisclosedagainstthemediumowbyspringforce(controlfunctionA,
CFA)orbycontrolpressure(controlfunctionB,CFB).
Asthemediumpressureisundertheswivelplate,thispressurecontributestotheopeningofthevalve
CFA/CFI CFB/CFI
Figure 7: Flow below the seat (closing against medium)