Bosch Rexroth SV20PB4-4X/V pilot-operated check valve

SV20PB4-4X/V, manufacturer material number R901444120, is a Bosch Rexroth SV size 20 hydraulically pilot-operated check valve for subplate mounting to ISO 5781. It uses internal pilot-oil drain, with Y plugged, FKM seals and no decompression stage.

Flow is free from A to B. Reverse B-to-A flow is blocked until pressure at X opens the poppet. Opening-pressure code 4 corresponds to a forward opening-pressure class of 10 bar in the original manufacturer table. This class is distinct from the pilot pressure needed to release a loaded circuit. Required pilot pressure depends on load and return pressure, and must be read from the applicable control-pressure/load-pressure curves.

The technical reference is the original manufacturer publication RE21468, edition 2024-02. Its size-specific component operating-pressure limit is 315 bar, with a catalog control range of 5–315 bar; 5 bar is not a universal pilot-opening requirement. No independent unrestricted Y-port pressure rating or application safety certification is established by these data. The internal-drain execution must be assessed with the actual circuit backpressure.

The FKM fluid and ambient range in this reference is −15 to +80 °C, with viscosity 2.8–500 mm²/s and ISO 4406 cleanliness class 20/18/15. The pressure-drop and pilot-pressure curves use HLP46 at 40 ± 5 °C. The subplate and mounting screws are separately ordered. Representative manufacturer SV/SL subplate-mounting drawing. The Y connection applies to SL and is plugged on SV; the exact size and opening-pressure version are defined separately.