 2025 Sun Hydraulics 1 of 2

MODEL

RPKSRPKS

Pilot-operated, balanced poppet relief valve

SERIESSERIES 4 / 4 / CAPACITY:CAPACITY: 760 L/min. / 760 L/min. / CAVITY:CAVITY: T-18A T-18A

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

Pilot-operated, balanced-poppet relief cartridges are normally closed pressure regulating

valves. When the pressure at the inlet (port 1) reaches the valve setting, the valve starts to

open to tank (port 2), throttling flow to regulate the pressure. These valves are accurate,

smooth, quiet, fast, and have low pressure rise vs. flow.

TECHNICAL DATATECHNICAL DATA

Cavity T-18A

Series 4

Capacity 760 L/min.

Maximum Operating Pressure 350 bar

Factory Pressure Settings Established at 15 L/min.

Maximum Valve Leakage at Reseat 0,7 cc/min.

Response Time - Typical 7 ms

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

Valve Hex Size 41,3 mm

Valve Installation Torque 474 - 508 Nm

Adjustment Screw Internal Hex Size 4 mm

Locknut Hex Size 15 mm

Locknut Torque 9 - 10 Nm

Seal kit - Cartridge Buna: 990318007

Seal kit - Cartridge EPDM: 990318014

Seal kit - Cartridge Polyurethane: 990018002

Seal kit - Cartridge Viton: 990318006

Model Weight 1.17 kg.

sunhydraulics.com/model/

RPKS

 2025 Sun Hydraulics 2 of 2

(L)(L)CONTROLCONTROL

LL Standard Screw Adjustment

CC Tamper Resistant - Factory Set

KK Handknob

WW Hex Wrench Adjustment

YY Tri-Grip Handknob

(A)(A)ADJUSTMENT RANGEADJUSTMENT RANGE

AA 100 - 3000 psi (7 - 210 bar),

1000 psi (70 bar) Standard

Setting

BB 50 - 1500 psi (3,5 - 105 bar),

1000 psi (70 bar) Standard

Setting

CC 150 - 6000 psi (10,5 - 420 bar),

1000 psi (70 bar) Standard

Setting

NN 60 - 800 psi (4 - 55 bar), 400 psi

(28 bar) Standard Setting

QQ 60 - 400 psi (4 - 28 bar), 200 psi

(14 bar) Standard Setting

WW 150 - 4500 psi (10,5 - 315 bar),

1000 psi (70 bar) Standard

Setting

(N)(N)SEAL MATERIALSEAL MATERIAL

NN Buna-N

EE EPDM

VV Viton

MATERIAL/COATINGMATERIAL/COATING

Standard Material/Coating

/AP/AP Stainless Steel, Passivated

/LH/LH Mild Steel, Zinc-Nickel

TECHNICAL FEATURESTECHNICAL FEATURES

Because the modulating occurs inside the cartridge, these valves are immune to most of the problems associated with cavitation,

namely noise and manifold erosion.

Cartridges configured with EPDM seals are for use in systems with phosphate ester fluids. Exposure to petroleum based fluids,

greases and lubricants will damage the seals.

Will accept maximum pressure at port 2; suitable for use in cross port relief circuits.

Valve is relatively insensitive to varying oil temperatures and oil borne contamination.

Main stage orifice is protected by a 150-micron stainless steel screen.

Back pressure on the tank port (port 2) is directly additive to the valve setting at a 1:1 ratio.

W and Y controls (where applicable) can be specified with or without a special setting. When no special setting is specified, the valve

is adjustable throughout its full range using the W or Y control. When a special setting is specified, this setting represents the

maximum setting of the valve.

Corrosion resistant cartridge valves are intended for use in corrosive environments and are identified by the model code suffix /AP

for external stainless steel components, or /LH for external zinc-nickel plated components. See the CONFIGURATION section for all

options. For further details, please see the Materials of Construction page located under TECH RESOURCES.

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

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