PILOT OPERATED SEQUENCE VALVE - Series VR4S Veljan Sequence Valve Series VR4S are pilot operated controls and enable a hydraulic system to operate in a sequence. Fluid is allowed to pass to a secondary system ( Port B ) after the primary system ( Port A ) pressure reaches the preadjusted value set at pilot spring. VR4S consists of a high flow poppet type seat valve section controlled by the low flow, adjustable pilot section mounted on top. Pressure setting is altered by means of a knurled knob. For tamper proof setting , acorn nut with lead seal is available as option. Optional vent valve VWO sandwiched between the pilot section and the main body can be used for venting the VR4S valves. Pilot drain can be taken out externally from a pilot head or from a subplate. Exceptionally fast response is obtained due to the precise ratio between the main piston area and its mass. The unique design features of pilot allows for accurate and stable secondary pressure controls. Precise adjustment and quick response eliminate pressure variation and system shocks. Port A is connected to the primary section and port B to the secondary section of a hydraulic system. At low pressure, flow entering to Port A is blocked by the main poppet. Pressure at Port A passes through orifices to the pilot section as well as to the top of the main poppet. No flow takes place to this section until the pressure overcomes the spring setting of the pilot cone. The pilot cone is lifted from its seat releasing a small pilot flow through external drain and resulting in a pressure drop across the main poppet. The main poppet opens and allows only enough flow to the secondary system ( Port B ) maintaining the primary system pressure ( Port A ) at the pre-set value until the pressure at secondary port rises to the same value. As soon as the pressure is equal in both ports, the control piston in the pilot section closes preventing loss of oil through external drain. The main poppet opens fully and allows pressure at A and B to rise to a higher value than set. In such a situation the VR4S works as a gate valve allowing flow in either

PILOT OPERATED SEQUENCE VALVE - Series VR4S Mounting position Port sizes (nominal] Ambient temperature Special working conditions Pressure control range Maximum operating pressure Pilot operated Sequence Valve Poppet type Consult VELJAN Minimum - depends on flow PortX (pilot) PortY, Yi (Pilot drain Without pressure to tank Fluid Temperature Range Mineral oil as per DIN 51 524/25 or other fluids on request Viscosity Range Optimum operating viscosity Seal compatibility Cleanliness recommended Code 1 (Buna N) or Code 5 (Viton) (contact Veljan with specific oil details] Better than NAS 1 638 Class...

PILOT OPERATED SEQUENCE VALVE - Series VR4S ORDERING CODE Max. Pressure of Valve Body Body Mounting 0- Cartridge Yi port = V4" NPTF Threaded body 6 - Threaded body VR4S03 = ^" B.S.PP D- Threaded body VR4S06 = ^"B.S.PP Subplate mounting (Yi port - W NPTF with drain line code 2] SAE - 4 (7/16" - 20 UNF) with drain line code 2] (Yi Port = V4" B.S.PP ; with drain line code 2] Flange body 2 - Flange body ( X,Yi port - V¡ NPTF ] 1 ) Only with Drain line code 2 2) Port Yi is only available at Drain line (code2) external from pilot head. Seal Class Design letter Solenoid Voltage (Omit for non vent version]...

PILOT OPERATED SEQUENCE VALVE - Series VR4S Panel opening Block mounting face Location hole 1 ) Optional from pilot head or subplate. Port Yi is only available at Drain line (code 2) external from the pilot head Note : For details of Subplate & mtg. screws please refer page 48

PILOT OPERATED SEQUENCE VALVE - Series VR4S Location hole Mounting screws are included in subplate order. For valves ordered without subplate, mounting screws must be ordered separately.

PILOT OPERATED SEQUENCE VALVE - Series VR4S CARTRIDGE WITH PILOT VALVE VR4S03 (3/8") ( #0, #E & #G ) Orifice position [orifice is content of delivery) 1) Port Yi is only available at Drain line (code 2) external from the pilot head. * Mounting screws must be ordered separately