SUN HYDRAULICS
PSDLLBN812

$291.10 USD

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SUN HYDRAULICS
Material:PSDLLBN812
Model:PSDL-LBN@812
Summary:Cartridge

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***Disclaimer: The following summary contains information gathered from various sources such as product descriptions, technical specifications and catalogs. While efforts have been made to provide accurate details, inaccuracies may occur. It is advised to verify all information by contacting Sun Hydraulics directly.***
The Sun Hydraulics PSDLLBN812 (Material Number: PSDLLBN812) is an electroproportional, direct-acting reducer-reliever valve designed to manage hydraulic pressure efficiently. This valve reduces high primary pressure at the inlet port 2 to a consistent, lower pressure at port 1 while offering a full flow relief function from port 1 to tank port 3. The valve is initially biased to the relieving mode, but energizing the coil connects port 2 to port 1, with increased current proportionally raising the reduced pressure at port 1. Should the pressure at port 1 surpass the coil-induced setting, it is relieved to port 3. The valve's design ensures insensitivity to pressure changes at port 3 by draining through port 4. The PSDLLBN812 offers reliable performance even in contaminated systems due to its direct-acting concept, which is particularly effective under dead-headed conditions. It features a slightly open transition from reducing to relieving mode for superior pressure control and dynamic response. Manual control is optional for emergency adjustments or boosting settings during power failures. This model supports up to a maximum operating pressure of 5000 psi (350 bar) and has a capacity of handling flow rates up to 5 gpm (20 L/min). The valve's construction minimizes internal binding risks due to excessive installation torque or machining variations. For optimal functionality, an amplifier with current sensing and adjustable dither between 100-250 Hz is recommended. The valve also supports reverse flow from reduced pressure port 1 back to inlet port 2 but may require an additional check valve for free flow in reverse circuits. With its robust design and operational versatility, this Sun Hydraulics valve serves as a reliable component in hydraulic systems requiring precise pressure management and relief functions.

Description

This electro-proportional, direct-acting reducer/reliever valve reduces a high primary pressure at the inlet (port 2) to a constant reduced pressure at port 1, with a full flow relief function from port 1 to tank (port 3). The valve is biased to the relieving mode. Energizing the coil connects port 2 to port 1. Increasing the current to the coil will proportionally increase the reduced pressure at port 1. If pressure at port 1 exceeds the setting induced by the coil, pressure at port 1 is relieved to port 3. Draining port 4 makes the valve insensitive to pressure at port 3. This valve is open in the transition from reducing to relieving which provides good pressure control and dynamic response. Optional full manual control is available.

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.
Direct acting concept provides highly reliable operation in contaminated systems, especially at dead headed conditions.
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.
The transition from reducing to relieving is slightly open. The result is very good pressure control with oil consumption of about 0.1 gpm (0,4 L/min.).
For optimum performance, an amplifier with current sensing and adjustable dither should be used. Dither should be adjustable between 100 - 250 Hz.
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.
Uses for the 'L' manual screw adjustment include: emergency valve setting during power failure or alternatively boosting the valve setting
With the 'L' adjustment screw, all ranges are factory set at zero (adjustment screw fully backed out). With the coil de-energized, clockwise adjustment of the screw will increase the spring bias load up to the maximum setting for that range. With the coil energized, any mechanical pressure setting is directly additive to the coil induced value.
By controlling the pressure at the drain (port 4), the effective setting of the valve can be increased over the nominal valve setting.
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.

Cavity	T-21A
Series	1
Capacity	5 gpm20 L/min.
Maximum Operating Pressure	5000 psi350 bar
Maximum Valve Leakage at 110 SUS (24 cSt)	20 in³/min.330 cc/min.
Adjustment - Number of Clockwise Turns to Increase Setting	55
Solenoid Tube Diameter	.75 in.19 mm
Valve Hex Size	7/8 in.22,2 mm
Valve Installation Torque	30 - 35 lbf ft41 - 47 Nm
Adjustment Screw Internal Hex Size	5/32 in.4 mm
Locknut Hex Size	9/16 in.15 mm
Locknut Torque	80 - 90 lbf in.9 - 10 Nm
Model Weight (with coil)	1.20 lb0,55 kg
Seal kit - Cartridge	Viton: 990-021-006
Seal and nut kit - Coil	Viton: 990-770-006Viton: 990-770-006

Show FAQ

Will your reducing/relieving valve relieve my pump to tank?	No. A reducing/relieving valve throttles a supply of oil to maintain a set pressure in a secondary circuit. The valve is open until the secondary or downstream pressure rises to the setting of the valve at which time it starts to close to limit the pressure. If the secondary or downstream pressure is caused to go above the setting, the valve shifts into relieving mode and throttles the secondary circuit back to tank to prevent over-pressure. At no time can the valve connect the supply to tank.
How big is a drop of hydraulic oil?	There are exactly 250 Sun drops in a cubic inch or 15 in a cc.
Direct acting or pilot operated - what do I use?	Direct-acting valves are used to prevent over pressure, and pilot-operated valves are used to regulate pressure. If you are unsure, use a direct-acting valve. Sun's direct acting valves are very fast, dirt tolerant, stable, and robust. Sun's pilot-operated valves are moderately fast, they have a low pressure rise vs. flow curve, and they are easy to adjust.
Can I back flow through a reducing valve from port 1 to port 2?	Yes. A reducing or reducing/relieving valve is normally open. If the pressure in the secondary circuit is less than the setting, it will be open.2 caveats: (1) If the valve is in the reducing mode and you suddenly reverse the flow, the valve will not have time to open and will shift into relieving mode or (2) If the back flow generates a pressure drop through the valve that exceeds the setting, the valve will shift into the relieving mode.When in doubt, use a reverse flow check.
What are the tolerances on pressure settings for Sun's pressure control valves?	Pressure setting tolerances are listed in our Performance Data page. A link to this page can also be found in the Additional Resources tab of the applicable product page.
I need a reducer on B. Can I connect the drain to A?	Yes. If you look in the sandwich section you will see that we offer many such packages. When you are pressurizing B, A is connected to tank, allowing the reducer to do its job. When you reverse, the drain or tank port of the reducer is pressurized by A. This increases the setting of the reducer and helps keep the reducer open in the reverse flow direction.
What do you mean by maximum differential?	Our reducing valves are outside-in valves; the supply pressure on the outside of the working parts is higher than the inside. At some pressure differential, the outside (sleeve) will close in on the piston and cause the valve to stick. A D range is adjustable from 25 to 800 psi with a maximum differential of 2000 psi. This means you could set the valve at 600 psi and expect it to work correctly with a supply pressure of 2600 psi. The valve may work at higher differentials, but we do not recommend it. The W and C ranges are tested over their entire range with an inlet pressure of 5000 psi. All direct-acting valves are tested with an inlet pressure of 5000 psi.

Additional Resources

Notes:

Please verify cartridge clearance requirements when choosing a Sun manifold. Different valve controls and coils require different clearances.

SUN HYDRAULICSPSDLLBN812

Additional Resources

SUN HYDRAULICS
PSDLLBN812