I
MO-D52/R52
12
9/21 Rev. 0
Principle of Operation
See Fig.8, 9 and 12 for the encircled part numbers.
Direct operation
In the direct action (DA) type, the valve closes when the air-pressure to the diaphragm chamber
increases. When air-pressure is supplied from the instrument air connecting portion the diaphragm upper
case 102 to the diaphragm chamber, which consists of the diaphragm upper case, the diaphragm 108
and the diaphragm plate 104, both of which are closely set together, are activated to press down the
spring 109 and move downward. At the same time, the actuator rod 106 fixed with the diaphragm and
the diaphragm plate moves down.
Subsequently the movement of the actuator rod is transferred to the valve stem 5 via the connector
112 to move it to the valve-close position. Then when the air-pressure to the diaphragm chamber is
decreased, the diaphragm, the diaphragm plate and the actuator rod move upward by means of the
reaction force of the spring and the stem also moves toward the valve-open position.
Reverse operation
In the reverse action (RA) type, the valve opens when the air-pressure to the diaphragm chamber
increases. When air-pressure is supplied from the instrument air connecting port on the diaphragm lower
case 103 to the diaphragm chamber, which consists of the diaphragm lower case, the diaphragm 108
and the diaphragm plate 104, both of which are closely set together, are activated to press up the spring
109 and move upward. At the same time, the actuator rod 106 fixed with the diaphragm and the
diaphragm plate moves upward.
Subsequently the movement of the actuator rod is transferred to the valve stem 5 via the connector 112
to move it to the valve-open position. Then when the air-pressure to the diaphragm chamber is
decreased, the diaphragm, the diaphragm plate and the actuator rod move downward by means of the
reaction force of the spring and the stem also moves toward the valve-closed position.
