SUN HYDRAULICS
PSDBOBN

$125.10 USD

SUN HYDRAULICS
Material:PSDBOBN
Model:PSDB-OBN
Summary:Cartridge

Quantity in stock: 0

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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 PSDBOBN (PSDBOBN) is a direct-acting, pressure reducing/relieving valve designed to maintain a constant reduced pressure at port 1 while offering full-flow relief from port 1 to tank port 3. This valve features a damped construction for stable operation, making it suitable for use with high reduced pressure applications. It is particularly effective in accumulator circuits due to its design that minimizes secondary circuit leakage by eliminating pilot control flow. The direct-acting mechanism ensures reliable performance even in contaminated systems and provides superior dynamic response compared to pilot-operated models, although it may not be ideal for counterbalancing applications due to the transitional step between reducing and relieving modes. The valve accommodates a maximum pressure of 3000 psi at port 3 and can handle up to 5000 psi inlet pressure across all spring ranges. Pressure on drain port 4 directly affects the valve setting at a 1:1 ratio, with limits up to 5000 psi. Notably, leakage from port 3 is proportional to the pressure differential and inversely proportional to viscosity, necessitating careful monitoring in specific applications. The Sun floating style construction helps prevent internal binding due to installation or machining variations. Installation requires a cavity T-21A with series 1 capacity of up to 10 gpm and proper torque specifications for various components like the adjustment screw and locknut. The PSDBOBN model weighs approximately .30 lb and includes options for Viton seal kits. Users should consider adding separate check valves if reverse free flow is needed in their circuit designs, as the main spool may close under certain conditions when reverse flow occurs from reduced pressure port 1 back to inlet port 2.

Description

Direct-acting, pressure reducing/relieving valves reduce 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). Draining port 4 makes the valve insensitive to pressure at port 3. These valves incorporate a damped construction for stable operation allowing the use of high reduced pressure.

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.
Unlike pilot operated versions, direct acting valves exhibit a transitional step between reducing and relieving modes. This step equals 5% of the high end of the adjustment range, independent of the valve setting. Therefore, these valves may not be suitable for counterbalancing applications.
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.
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.
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	10 gpm40 L/min.
Factory Pressure Settings Established at	blocked control port (dead headed)blocked control port (dead headed)
Maximum Operating Pressure	5000 psi350 bar
Maximum Valve Leakage at 110 SUS (24 cSt)	2 in³/min.@1000 psi30 cc/min.@70 bar
Adjustment - Number of Clockwise Turns to Increase Setting	55
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	.30 lb0,15 kg
Seal kit - Cartridge	Viton: 990-021-006

Show FAQ

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.
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.

Additional Resources

Notes:

For Series 1 cartridges configured with an O control (panel mount handknob), a .75 in. (19 mm) diameter hole is required in the panel.

SUN HYDRAULICSPSDBOBN

Additional Resources

SUN HYDRAULICS
PSDBOBN