n° 8_0083 CONVERSION DA ⇒ SR OMAL S.p.A. Via Ponte Nuovo 11 - 25050 RODENGO SAIANO (BS) ITALY Tel. 030/8900145 r.a. - Fax 030/8900423

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CONVERTING A DOUBLE ACTING (DA) ACTUATOR INTO SPRING RETURN (SR) SR ACTUATOR OMAL Double Acting pneumatic actuators differ from Spring Return ones because of the way components are assembled. As the piston slots are approx. 15 degree off the center line, the two extreme positions (completely closed or completely open pistons) yield two different torque values. Specifically actuators are required to generate the highest torque value (i.e. the highest of the two mentioned above) in the “closed valve” position (where the valve gives the highest resistance). In a DA actuator the valve closes when...

SECOND STEP: ROTATE THE SCOTCH YOKE AND TURN THE PISTONS UPSIDE DOWN Acting on the output shaft, give the scotch yoke a 90° rotation and then turn the pistons upside down by 180°. THIRD STEP: RIASSEMBLING THE PISTONS Put the pistons back in trying to center the slots (the two pistons need to go in at the same time without using any hammer or tool which may damage the actuator mechanism). FORTH STEP: PUT THE SR CAPS ON OMAL SR caps come with springs. The springs pre-loaded at the factory and shall not be removed or altered in any way for any reason. 2 Conversion DA⇒SR 2000 rif. 01 - n° 8_0083...