M6 SERIES IOM
6th EDITION
ISSUED 12/2014
10
C. Fail Positions
The Contromatics actuator standard operation is counterclockwise to open and clockwise to close. This is referred
to as a “fail clockwise” configuration or FCW. However, it is also available in an FCCW or “fail
counterclockwise” configuration. Figures 4.5 & 4.6 show the same actuator with the piston and pinion orientation
changed to convert the actuator from the FCW to the FCCW configuration. FCW is referred to as “fail closed”
and FCCW as “fail open” due to its intended effect on the valve. In the diagrams below, the hollow arrows show
the direction the pistons move due to the spring force, and the solid arrows show rotation of the pinion as it travels
to the fail position.
FCW (Fail Closed) Fig.4.5
Fig. 4.5 shows a FCW, spring return actuator going from the open position (left) to the fail, or closed, position
(right).
FCCW (Fail Opened) Fig.4.6
Fig. 4.6 shows a FCCW, spring return actuator going from the open position (left) to the fail, or closed, position
(right).
NOTE:
All statements above assume the valve is a quarter turn valve that opens counterclockwise and closes
clockwise. Further, it also assumes that the actuator is spring return Since a double acting actuator will always fail
in its last position (discounting any forces the valve may exert on the actuator). See also Table below.
