Samson 3525 Mounting And Operating Instructions

12 EB 8823 ENDesign and principle of operation3 Design and principle of oper-ationThe single-seated Type 3525 Globe Valve iscombined with a SAMSON Type 3571Pneumatic Actuator (see Fig. 4).The seat (4) and plug with plug stem (5) areassembled in the body (1). The plug stem isconnected to the actuator stem (A7) by thestem connector clamps (A26) and is sealedby a spring-loaded V-ring packing (16). Thesprings in the pneumatic actuator (A) are lo-cated either above or below the diaphragmdepending on the selected fail-safe action(see section 3.1). A change in the signalpressure acting on the diaphragm causes theplug to move. The actuator size is deter-mined by the diaphragm area.The medium flows through the valve in thedirection indicated by the arrow. The stan-dard valve body version normally operatesin the flow-to-open direction (FTO). The me-dium flows across the plug from bottom totop. The compact valve body versions nor-mally operate in the flow-to-close direction(FTC). The medium flows across the plugfrom top to bottom.The valves have a safety bleed to detectdamaged or worn O-rings.A rise in signal pressure causes the force act-ing on the diaphragm in the actuator to in-crease. The springs are compressed. De-pending on the selected direction of action,the actuator stem retracts or extends. As aresult, the plug position in the seat changesand determines the flow rate through thevalve.There are three versions available:− Standard globe valve with flanges (seeFig. 3) or threaded ends− Compact globe valve with threaded ends− Compact T-pattern valve with threadedends (see Fig. 5)Standard globe valves >Class 900 with FKMO-ring are equipped with an additional sup-port ring (244) which is inserted into thegroove of the bottom O-ring (17).Compact T-pattern valves are equipped witha screw plug (112). The screw plug can bepositioned either at the bottom outlet or –depending on the flow direction – at the sideoutlet. It must not be positioned at the inlet.ActuatorsIn these instructions, the combination with aType 3571 Pneumatic Actuator is described.The pneumatic actuator for the standard ver-sion can be replaced by another Type 3571Pneumatic Actuator in a different size, butwith the same travel.Î Observe the maximum permissible actu-ator force.If the travel range of the actuator is largerthan the travel range of the valve, the springassembly in the actuator must be preloadedso that the travel ranges match. See associ-ated actuator documentation.Note