Shijiazhuang Laiye Import& Export Trading Co., Ltd. is one of the leading manufacturers and suppliers of da series pilot operated unloading valve 31.5 mpa in China, also supports customized service. If you're going to wholesale high quality da series pilot operated unloading valve 31.5 mpa made in China, welcome to get pricelist from our factory.
Product Summary
The DA Series Pilot Operated Unloading Valve 31.5 MPa is a pilot-operated unloading valve that diverts pump flow back to tank when a preset pressure is reached. It is available in three specifications: 10, 20, and 30, with maximum flow ratings of 60 L/min, 120 L/min, and 240 L/min respectively. All specifications share a maximum working pressure of 31.5 MPa and a pressure adjustment range of 5, 10, 20, and 31.5 MPa. The design number is 50.
Why an Unloading Valve Exists
Think about a pump that keeps running at full pressure when nothing in the system needs flow. That's wasted energy. The oil gets hot. The power bill climbs. An unloading valve stops that. Once pressure reaches the set point, the valve opens and dumps pump flow back to tank. The pump runs unloaded. When pressure drops below the set point, the valve closes and the pump starts building pressure again.
The DA Series is pilot operated. The main spool doesn't get pushed by a heavy spring - it gets shifted by pilot pressure. That's what lets it work at higher flows without a stiff spring that would wear out or need constant adjustment.
Three Flow Classes
The difference between the three specs is flow capacity. Nothing else changes.
Spec 10 is the smallest - it handles up to 60 L/min. Spec 20 goes to 120 L/min. Spec 30 takes 240 L/min. All three have the same maximum working pressure (31.5 MPa) and the same adjustment range (5, 10, 20, or 31.5 MPa).
Picking one is simple. Look at your pump output. If it's around 60 L/min, go with spec 10. Around 120 L/min, spec 20. Around 240 L/min, spec 30.
Design number 50 is the same across all three. It's the internal design version, and you'll need it when ordering replacement parts.
What the Pressure Adjustment Range Means
The adjustment range covers 5, 10, 20, and 31.5 MPa. These are the set points at which the valve will unload the pump. The correct setting depends on the system. If the system needs to maintain 10 MPa, the valve should be set to unload at that pressure. If it needs 20 MPa, the valve should be set accordingly.
The adjustment range is specified as discrete values, not a continuous range from 5 to 31.5 MPa. This means the valve is configured for one of these set points at the time of order, or adjusted within the available spring range. If your system requires a specific unloading pressure, confirm the setting before ordering.
Where This Valve Fits
The DA Series Pilot Operated Unloading Valve 31.5 MPa is used in hydraulic circuits that need pressure-controlled unloading. This includes systems with accumulators, where the pump should unload once the accumulator is charged. It also includes dual-pump systems, where one pump unloads when the other takes over the flow demand.
The valve is not a relief valve. A relief valve modulates flow to hold pressure. An unloading valve shifts fully to unload the pump. The difference matters in systems where heat generation and power consumption are concerns. An unloading valve reduces both during periods when the system does not need flow.
Installation and Maintenance Notes
The DA Series mounts on a subplate or manifold. The mounting surface must be flat and clean. Tighten the bolts evenly to avoid distorting the valve body.
Keep the hydraulic oil clean. Contamination is the leading cause of spool sticking and seal wear. Replace filters on schedule. If the valve becomes sluggish or fails to unload, check the pilot orifice for blockage. A partially blocked pilot passage can prevent the main spool from shifting.
Check for external leakage at the mounting face and port connections. A small weep usually indicates a damaged O-ring or an uneven mounting surface. Address it before it becomes a larger leak.
About the Manufacturer
The DA Series is produced by Shijiazhuang Laive Import & Export Trading Co., Ltd., part of Hebei Onederful® Hydraulic Technology Co., Ltd. The company was founded in 1988 and has more than 35 years of experience in pressure valve components. It employs over 200 people and ships more than 10,000 containers of specialized products each year to customers in more than 20 countries. ISO9002 certification was obtained in 2000.
For full company information, visit About Us.
FAQ
Q: How do I choose between specification 10, 20, and 30?
A: Match the flow rating to your system's maximum flow. Specification 10 is rated at 60 L/min. Specification 20 is rated at 120 L/min. Specification 30 is rated at 240 L/min. All three share the same maximum working pressure of 31.5 MPa and the same pressure adjustment range.
Q: Can the unloading pressure be adjusted in the field?
A: The pressure adjustment range covers 5, 10, 20, and 31.5 MPa. The valve is configured for one of these set points at the time of order. Field adjustment may be possible within the available spring range. For a specific unloading pressure, confirm the setting with the supplier before ordering.
Q: What is the function of the pilot stage in this valve?
A: The pilot stage controls the main unloading spool. When system pressure reaches the set value, the pilot stage directs oil to shift the main spool, which unloads the pump. This allows stable operation at higher flows without a heavy spring.
Q: How is this different from a relief valve?
A: A relief valve modulates flow to hold pressure. An unloading valve shifts fully to unload the pump when the set pressure is reached, reducing heat and power consumption. It is typically used in accumulator circuits or dual-pump systems.
Q: What maintenance does the valve require?
A: Keep the hydraulic oil clean and replace filters on schedule. Check for external leakage at the mounting face and port connections. If the valve becomes sluggish or fails to unload, check the pilot orifice for blockage.
Q: What is the warranty and typical delivery time?
A: The warranty is 12 months against B/L date. Standard delivery time is 10–14 business days for items not in stock, or 2–3 business days if stock is available.
Hot Tags: da series pilot operated unloading valve 31.5 mpa, China da series pilot operated unloading valve 31.5 mpa, manufacturers, suppliers, factory, directional flow control valve, hydraulic directional, hydraulic monoblock solenoid directional control valve, hydraulic pilot operated directional control valve, monoblock spool valve, sectional valve
