Failure Modes - Single Acting (Spring Return); Changes For Reverse Acting - EL-O-MATIC F20 Manual De Instalación Y Operación

5.0 Failure Modes / Modes de panne / Modos de fallo
1. Fail Close - Direct acting
Input
signal Rotary
actuator
1 A
F20
2
5.3
2. Fail Open - Direct acting
Input
signal
actuator
1 A
F20
2
5.4
Input 3. Fail Close - Reverse acting
signal
Rotary
actuator
1
A
F20
2
5.5
Input
4. Fail Open - Reverse acting
signal
Rotary
actuator
1 A
F20
2
5.6
Linear
actuator
A
Close
Rotary Linear
actuator
A
Close
Linear
actuator
A
Close
Linear
actuator
A
Close
22
5.2 Failure Modes - Single Acting (Spring
return)
Spring return actuators may be "fail open" or "fail close"
depending on what happens when the air fails. This air failure
mode must be built into the actuator and maintained when the
actuator is built onto the valve.
In addition both these air failure modes may be either direct
acting or reverse acting depending on what happens at the
positioner when the 4 - 20 mA. signal fails or is reduced to it's
lowest level.
Action Air connection
1
Direct A Block
Direct Block
Reverse A Block
Reverse Block

5.2.1 Changes for Reverse Acting

To change from the standard setup to reverse acting:
1. Change the tubing (see fig. 5.3 to 5.6).
2. Plug the unused actuator port.
3. Remove the cover.
4. Change the action jumper setting by setting both jumpers to
the right side (see fig. 5.2).
5. Replace the cover taking care that the "O" ring seal is in
place and the fixing screws are tightened correctly.
Failure
2 Air Signal
Close Close
A Open Close
Open Open
A Close Open
DOC,F20,EFS Rev.: -