SUN HYDRAULICS
QPADLBN
- SUN HYDRAULICS
- Material:QPADLBN
- Model:QPAD-LBN
- Summary:Cartridge
Due to extremely high demand, please call 800-289-1330 for availability
***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 QPADLBN (QPADLBN) is an advanced accumulator sense, pump unload pilot valve designed to efficiently manage hydraulic systems by sensing pressure in an accumulator at port 1. When the pressure reaches the designated valve setting, it connects port 2 to port 3 to vent a relief valve and unload the pump, ensuring optimal system performance. This model features a precise 50% ratio between unload setting and reset; if the pressure at port 1 falls below half of the valve setting, port 2 is blocked from port 3, reactivating the pump to recharge the accumulator. Notably, this valve requires a separate check valve between port 1 and the pump for proper operation. The QPADLBN offers reliable performance with a minimal pressure differential between unload and reset within \u00b11% of the stated ratio plus an additional potential of up to 25 psi due to dynamic seal friction. Its spool design maintains a fixed differential ratio through diameters that resist wear over time. Additionally, minimum clearances between spool and sleeve paired with a seal on the pilot piston diameter reduce silting risks significantly. For effective application, this cartridge necessitates a separate drain line to mitigate erratic operations from tank line pressure fluctuations. System designers should carefully select adjustment ranges due to impacts from system pressure drops and flows on unloading valves' operations. The valve supports high flow rates which may result in significant pressure drops impacting its differential functionality. Constructed with Sun's floating style design, this model minimizes potential binding issues caused by excessive installation torque or machining variations in cavity/cartridge setups. It fits into Cavity T-11A Series 1 with a maximum operating pressure of 5000 psi (350 bar) and has a pilot flow capacity of 46 in\u00b3/min (0.75 L/min). The installation torque ranges from 30-35 lbf ft (41-47 Nm), ensuring secure setup for optimal hydraulic management applications.
The Sun Hydraulics QPADLBN (QPADLBN) is an advanced accumulator sense, pump unload pilot valve designed to efficiently manage hydraulic systems by sensing pressure in an accumulator at port 1. When the pressure reaches the designated valve setting, it connects port 2 to port 3 to vent a relief valve and unload the pump, ensuring optimal system performance. This model features a precise 50% ratio between unload setting and reset; if the pressure at port 1 falls below half of the valve setting, port 2 is blocked from port 3, reactivating the pump to recharge the accumulator. Notably, this valve requires a separate check valve between port 1 and the pump for proper operation. The QPADLBN offers reliable performance with a minimal pressure differential between unload and reset within \u00b11% of the stated ratio plus an additional potential of up to 25 psi due to dynamic seal friction. Its spool design maintains a fixed differential ratio through diameters that resist wear over time. Additionally, minimum clearances between spool and sleeve paired with a seal on the pilot piston diameter reduce silting risks significantly. For effective application, this cartridge necessitates a separate drain line to mitigate erratic operations from tank line pressure fluctuations. System designers should carefully select adjustment ranges due to impacts from system pressure drops and flows on unloading valves' operations. The valve supports high flow rates which may result in significant pressure drops impacting its differential functionality. Constructed with Sun's floating style design, this model minimizes potential binding issues caused by excessive installation torque or machining variations in cavity/cartridge setups. It fits into Cavity T-11A Series 1 with a maximum operating pressure of 5000 psi (350 bar) and has a pilot flow capacity of 46 in\u00b3/min (0.75 L/min). The installation torque ranges from 30-35 lbf ft (41-47 Nm), ensuring secure setup for optimal hydraulic management applications.
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 50% ratio between unload setting and reset; when pressure at port 1 falls below 50% 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, QCDD, includes a free-flow check valve for pump flows under 12 gpm (50 L/min).
- The pressure differential between unload and reset will be within +/- 1% of the stated ratio of the valve with up to an additional 25 psi (1,7 bar) due to dynamic seal friction.
- 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.
| Cavity | T-11A |
| Series | 1 |
| Capacity | 46 in³/min.0,75 L/min. |
| Maximum Operating Pressure | 5000 psi350 bar |
| Pilot Flow Capacity | 46 in³/min.0,75 L/min. |
| 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 | .35 lb0,15 kg |
| Seal kit - Cartridge | Viton: 990-011-006 |
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- Sun's Floating Style Screw-In Cartridge
- Performance Data
- Sun Model Code Explanation; 999-901-334
- Units of Measure, Settings, and Conversions
- Cartridges: Materials of Construction
- Cavity Information (S-171) and Tooling
