SUMMARY:  Cartridge

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The accumulator sense, pump unload pilot valve is used to sense pressure in an accumulator at port 2 of the valve and when the pressure at port 2 reaches the valve setting, port 3 connects to port 4 to vent a relief valve and unload the pump. This valve has a 30% ratio between unload setting and reset; when pressure at port 2 falls below 70% of the valve setting, port 3 is blocked from port 4 and the pump will come back online to recharge the accumulator. The integral free-flow check valve is suitable for pump flows up to 12 gpm (50 L/min). For higher capacity pumps, another version of accumulator sense, pump unload cartridge, QPAC, which requires a separate check cartridge is available.

  • The pressure differential between unload and reset will be within +/- 1% of the stated ratio of the valve with up to an additional 25 psi (1,7 bar) due to dynamic seal friction.
  • The accumulator sensing area is positively sealed.
  • The spool design of this valve allows it to maintain a fixed differential ratio because the areas are created by diameters on the spool that will not wear or change with use.
  • Minimum clearances between the spool and sleeve and a seal on the pilot piston diameter significantly reduce the potential for silting.
  • When applying this cartridge, a separate drain line is required to prevent erratic operation caused by tank line pressure fluctuations.
  • NOTE: Careful consideration should be given when selecting an adjustment range. System pressure drops and flows tend to affect the operation of unloading valves. Low operating pressures combined with low differentials result in a very narrow band between unload and reset, requiring precise system design. High flow rates typically mean high pressure drops, which subtract from the differential the valve has to work with.
  • Sun has designed a variety of standard accumulator/pump unload assemblies with a variety of features. These assemblies can be found on our website under SOLUTIONS: ACCUMLATOR SENSE, PUMP UNLOAD.
  • Incorporates the Sun floating style construction to minimize the possibility of internal parts binding due to excessive installation torque and/or cavity/cartridge machining variations.

Capacity15 gpm60 L/min.
Maximum Operating Pressure5000 psi350 bar
Check Cracking Pressure4 psi0,3 bar
Pressure Drop, Port 1 to Port 2100 psi@15 gpm7 bar@60 L/min.
Pilot Flow Capacity46 in³/min.0,75 L/min.
Adjustment - Number of Clockwise Turns to Increase Setting55
Valve Hex Size7/8 in.22,2 mm
Valve Installation Torque30 - 35 lbf ft41 - 47 Nm
Adjustment Screw Internal Hex Size5/32 in.4 mm
Locknut Hex Size9/16 in.15 mm
Locknut Torque80 - 90 lbf in.9 - 10 Nm
Model Weight.35 lb0,15 kg
Seal kit - CartridgeViton: 990-021-006

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