SF150A1-1-4X/

The SF150A1-1-4X/ prefill valve is produced by Bosch Rexroth as part of the SF Prefill Valves series. It is used in hydraulic automation to permit rapid filling and emptying of large cylinders while separating low tank pressure from the high-pressure working circuit. The valve mounts by a flange connection, simplifying integration into manifold blocks or cylinder heads. Clean operating fluid is required, and the permissible contamination level is ISO 4406 code 20/18/15 to protect the sealing edges and seating surfaces. During forward flow the control spool presents an effective area of 38.5 cm², determining the pilot force needed to shift the poppet. Port A is limited to 16 bar, so low return pressure must be maintained on that side. Pre-decompression is provided, allowing the main poppet to open gradually and reduce pressure shocks during switching. The unit can be installed in any orientation, which gives designers flexibility in compact power unit layouts.

For reverse flow the main poppet offers an effective area of 153.9 cm², enabling high flow rates with moderate pilot pressure. A pilot poppet area of 3.8 cm² defines the initial opening force when the valve begins to lift, ensuring controlled transition from closed to open states. The high-pressure lines connected to ports B, x, and y may reach 350 bar, so the body and seating components are sized for heavy-duty industrial presses and die-casting machines. These areas and pressure ratings together set the operating envelope, allowing the valve to manage large volume changes quickly while keeping pressure losses low.