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Pressure Ramp Up for Fixed Displacement Pumps

The anti-shock relief valve like RP*T has a fixed ramp time of about 300 ms and controls the relief function of the SC*AA FD*. A flow control valve can be used to increase the ramp time.


  • Direct-acting sequence:   SC*A
  • Relief valves as pilot:    RP*T
  • Flow control:                    FD*A    
  • 2/2 way directional valve:    DL*A
Benefits of this circuit arrangement:
  • The 2/2-way DL*A directional valve fully unloads a pump to tank. When the pump is brought on line by energizing DL*A, the pressure build up in the system will follow ramp times as shown in the graph. The ramp time is adjusted via a FD*A with a flow rate of 0.25 to 1 gpm.
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