 2020 Sun Hydraulics 1 of 2

MODEL

QPAA

15%, accumulator sense, pump unload valve - pilot capacity

SERIES 1 / CAPACITY: 0,75 L/min. / CAVITY: 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 15% ratio between unload setting and reset; when pressure at port 1 falls below

85% 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, QCDA, includes a free-flow check valve for pump flows under 12 gpm (50 L/min).

TECHNICAL 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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QPAA

 2020 Sun Hydraulics 2 of 2

(L)CONTROL

L Standard Screw Adjustment

C Tamper Resistant - Factory Set

(A)ADJUSTMENT RANGE

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

(70 bar) Standard Setting

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

(35 bar) Standard Setting

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

psi (140 bar) Standard Setting

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

bar) Standard Setting

(N)SEAL MATERIAL

N Buna-N

V Viton

MATERIAL/COATING

Standard Material/Coating

/LH Mild Steel, Zinc-Nickel

TECHNICAL FEATURES

The pressure differential between unload and reset will be within +3/-2% 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 CURVES

Model Code Example: QPAALANCONFIGURATION OPTIONS