 2025 Sun Hydraulics 1 of 2

MODEL

QPACQPAC

30%, accumulator sense, pump unload valve - pilot capacity

SERIESSERIES 1 / 1 / CAPACITY:CAPACITY: 0,75 L/min. / 0,75 L/min. / CAVITY:CAVITY: T-11A T-11A

NOTE: DATA MAY VARY BY CONFIGURATION. SEE CONFIGURATION SECTION.

The accumulator sense, pump unload pilot valve is used to sense pressure in an accumulator

at port 1 of the valve and when the pressure at port 1 reaches the valve setting, port 2

connects to port 3 to vent a relief valve and unload the pump. This valve has a 30% ratio

between unload setting and reset; when pressure at port 1 falls below 70% of the valve

setting, port 2 is blocked from port 3 and the pump will come back online to recharge the

accumulator.

This valve requires a separate check valve between port 1 and the pump. Another version of

the accumulator sense, pump unload valve, QCDC, includes a free-flow check valve for pump

flows under 12 gpm (50 L/min).

TECHNICAL DATATECHNICAL DATA

Cavity T-11A

Series 1

Capacity 0,75 L/min.

Maximum Operating Pressure 350 bar

Pilot Flow Capacity 0,75 L/min.

Adjustment - No. of CW Turns from Min. to Max. setting 5

Valve Hex Size 22,2 mm

Valve Installation Torque 41 - 47 Nm

Adjustment Screw Internal Hex Size 4 mm

Locknut Hex Size 15 mm

Locknut Torque 9 - 10 Nm

Seal kit - Cartridge Buna: 990011007

Seal kit - Cartridge Polyurethane: 990011002

Seal kit - Cartridge Viton: 990011006

Model Weight 0.16 kg.

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QPAC

 2025 Sun Hydraulics 2 of 2

(L)(L)CONTROLCONTROL

LL Standard Screw Adjustment

CC Tamper Resistant - Factory Set

(A)(A)ADJUSTMENT RANGEADJUSTMENT RANGE

AA 1000 - 3000 psi (70 - 210 bar),

1000 psi (70 bar) Standard

Setting

BB 500 - 1500 psi (35 - 105 bar),

500 psi (35 bar) Standard

Setting

CC 2000 - 5000 psi (140 - 350 bar),

2000 psi (140 bar) Standard

Setting

DD 250 - 800 psi (18 - 55 bar), 250

psi (18 bar) Standard Setting

(N)(N)SEAL MATERIALSEAL MATERIAL

NN Buna-N

VV Viton

TECHNICAL FEATURESTECHNICAL FEATURES

The pressure differential between unload and reset will be within +2/-3% of the stated ratio of the valve.

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.

PERFORMANCE CURVESPERFORMANCE CURVES

Model Code Example: QPACLANModel Code Example: QPACLANCONFIGURATION OPTIONSCONFIGURATION OPTIONS