SUN HYDRAULICS
QPACLDN
$169.96 USD
- SUN HYDRAULICS
- Material:QPACLDN
- Model:QPAC-LDN
- Summary:Cartridge
Quantity in stock: 0
***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 QPACLDN (QPACLDN) is an advanced accumulator sense, pump unload pilot valve specifically designed to monitor pressure in an accumulator at port 1. When the pressure at this port reaches the predetermined setting, the valve facilitates a connection between port 2 and port 3 to vent a relief valve and unload the pump. Notably, this model features a 30% ratio between unload setting and reset, meaning that when the pressure at port 1 drops below 70% of the setpoint, port 2 is blocked from port 3, allowing the pump to recharge the accumulator. A separate check valve is required between port 1 and the pump for optimal operation. The design ensures a precise pressure differential between unload and reset within \u00b11% of the stated ratio, with up to an additional 25 psi due to dynamic seal friction. This valve's spool design maintains a fixed differential ratio as it resists wear over time. To reduce silting potential, minimum clearances are maintained between spool and sleeve, alongside a sealed pilot piston diameter. A separate drain line is necessary to avoid erratic operations from tank line pressure fluctuations. The QPACLDN requires careful selection of adjustment range due to system pressure drops and flow rates impacting unloading valves' operations. It incorporates Sun's floating style construction to mitigate internal part binding risks from installation torque or machining variations. With a cavity specification of T-11A Series 1 and a maximum operating pressure of 5000 psi (350 bar), this model supports a pilot flow capacity of .75 L/min with specific installation torque requirements for optimal performance.
The Sun Hydraulics QPACLDN (QPACLDN) is an advanced accumulator sense, pump unload pilot valve specifically designed to monitor pressure in an accumulator at port 1. When the pressure at this port reaches the predetermined setting, the valve facilitates a connection between port 2 and port 3 to vent a relief valve and unload the pump. Notably, this model features a 30% ratio between unload setting and reset, meaning that when the pressure at port 1 drops below 70% of the setpoint, port 2 is blocked from port 3, allowing the pump to recharge the accumulator. A separate check valve is required between port 1 and the pump for optimal operation. The design ensures a precise pressure differential between unload and reset within \u00b11% of the stated ratio, with up to an additional 25 psi due to dynamic seal friction. This valve's spool design maintains a fixed differential ratio as it resists wear over time. To reduce silting potential, minimum clearances are maintained between spool and sleeve, alongside a sealed pilot piston diameter. A separate drain line is necessary to avoid erratic operations from tank line pressure fluctuations. The QPACLDN requires careful selection of adjustment range due to system pressure drops and flow rates impacting unloading valves' operations. It incorporates Sun's floating style construction to mitigate internal part binding risks from installation torque or machining variations. With a cavity specification of T-11A Series 1 and a maximum operating pressure of 5000 psi (350 bar), this model supports a pilot flow capacity of .75 L/min with specific installation torque requirements for optimal performance.
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 30% ratio between unload setting and reset; when pressure at port 1 falls below 70% 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, QCDC, 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 |
Show FAQ
Additional Resources
- Sun Cartridges with EPDM Seals
- Sun Expands Corrosion-Resistant Solutions
- CavitySaver multi-function valves deliver single-cartridge solutions
- Series 4 PLUS Cartridges Offer Higher Flows with Lower Pressure Losses
- QuickDesign with SmartConnect Offers Drag-and-Drop Schematic Tool
- Accumulator Sense, Pump Unload Valves
- Sun Offers Zinc-Nickel Plating for Corrosion Resistance
- Manufacturing Sun Cartridge Cavities
- Circuit Savers
- Fluid and Temperature Recommendations
- 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