 2020 Sun Hydraulics 1 of 2

MODEL

PSDT

Direct-acting, pressure reducing/relieving main stage piloted from port 4

SERIES 1 / CAPACITY: 40 L/min. / CAVITY: T-21A

(X)CONTROL

X Not Adjustable

(F)BIAS PRESSURE

F 100 psi (7 bar)

(N)SEAL MATERIAL

N Buna-N

E EPDM

V Viton

CONFIGURATION

X Control Not Adjustable

F Bias Pressure 100 psi (7 bar)

N Seal Material Buna-N

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

The direct-acting reducer/reliever main section is meant to act as an interface between a low flow pressure source

at port 4 and a circuit with higher flow requirements. The valve will reduce a high primary pressure at the inlet (port

2) to a reduced pressure at port 1, with a full-flow relief function from port 1 to tank (port 3).

The valve incorporates a damped construction for stable operation allowing the use of high reduced pressure.

TECHNICAL DATA

Cavity T-21A

Series 1

Capacity 40 L/min.

Maximum Operating Pressure 350 bar

Maximum Valve Leakage at 110 SUS (24 cSt) 41 cc/min.

Valve Hex Size 22,2 mm

Valve Installation Torque 41 - 47 Nm

Seal kit - Cartridge Buna: 990021007

Seal kit - Cartridge EPDM: 990021014

Seal kit - Cartridge Polyurethane: 990021002

Seal kit - Cartridge Viton: 990021006

Model Weight 0.17 kg.

sunhydraulics.com/model/

PSDT

Model Code Example: PSDTXFNCONFIGURATION OPTIONS

 2020 Sun Hydraulics 2 of 2

TECHNICAL FEATURES

The valve is biased to the relieving mode with a 100 psi (7 bar) spring. Pressure at port 4 is directly added to the setting of the valve once this threshold is

exceeded. For example, 1000 psi (70 bar) at port 4 will result in a setting of 900 psi (63 bar) at port 1.

Maximum pressure at port 3 should be limited to 3000 psi (210 bar).

All spring ranges are tested for correct operation with 5000 psi (350 bar) inlet pressure.

Suitable for accumulator circuits since the absence of pilot control flow results in reduced secondary circuit leakage.

Direct acting concept provides highly reliable operation in contaminated systems, especially at dead headed conditions.

Direct operated version offers superior dynamic response compared to equivalent pilot operated models.

Pressure on the drain (port 4) is directly additive to the valve setting at a 1:1 ratio and should not exceed 5000 psi (350 bar).

Leakage specified in Technical Data is out of port 3 with a supply pressure of 2000 psi (140 bar) and the valve set at mid range. This leakage is directly proportional

to pressure differential and inversely proportional to viscosity expressed in centistokes.

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.

Full reverse flow from reduced pressure (port 1) to inlet (port 2) may cause the main spool to close. If reverse free flow is required in the circuit, consider adding a

separate check valve to the circuit.

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