Product Overview

　　Walvoil SD5/1-P(KG3-160)/28L/AET is a 1-spool hydraulic control valve and manual hydraulic directional control valve delivering 45 L/min flow at 315 bar maximum pressure.Designed for metallurgical,marine,and construction equipment hydraulic systems with G3/8”PABT ports.

　　Product Type Definition

　　A manual hydraulic directional control valve is a device that starts,stops,and directs fluid flow to hydraulic actuators such as cylinders or motors through manual lever actuation.This product category includes monoblock(one-piece body)and sectional(stackable)constructions,with classification by number of spools,circuit type(parallel,series,or tandem),and spool center configuration(open or closed).The Walvoil SD5/1-P is a single-section monoblock valve in the parallel circuit configuration(denoted by“-P”),which maintains full system pressure to all downstream sections simultaneously.This design is optimized for medium-flow applications up to 45 L/min,making it suitable for systems requiring simultaneous actuator operation without pressure loss across functions.

　　Key Specifications

　　Rated pressure:315 bar(4600 psi)

　　Rated flow:45 L/min(12 US gpm)

　　Number of sections:1

　　Circuit type:Parallel(P)

　　Port thread:G3/8”BSP(P,A,B,T)

　　Control type:Manual lever(spring return to center)

　　Spool diameter:16 mm

　　Spool stroke:6 mm

　　Maximum return line pressure:25 bar

　　Actuating force:<200 N

　　Leakage(A,B to T):15 cm³/min at 120 bar

　　Fluid temperature range:-15°C to+80°C(NBR seals)

　　Ambient temperature(mechanical control):-40°C to+60°C

　　Viscosity range:15 to 75 mm²/s(cSt)

　　Filtration requirement:10 to NAS 1638

　　Technical Highlights

　　Parallel circuit maintains full pressure to all functions.The parallel configuration ensures each downstream section receives the full system pressure of 315 bar,preventing pressure drop when multiple actuators operate simultaneously.For applications requiring high pressure but lower flow on individual functions,the parallel circuit maximizes available force per actuator.

　　Monoblock construction eliminates internal leakage paths.Unlike sectional valves that require sealing between stacked sections,the one-piece cast body of the SD5/1-P has no internal mating joints,reducing potential leak points by over 50%compared to multi-section alternatives.This design directly contributes to the rated leakage of only 15 cm³/min at 120 bar.

　　Integrated main relief valve and load check valve in P-channel.Factory-set pressure relief(adjustable from 50 to 220 bar)protects the system from overpressure events,while the load check valve prevents actuator drift due to backflow.For applications requiring low-temperature operation down to-40°C ambient,the unit maintains consistent manual actuation force below 200 N with appropriate low-viscosity fluid selection.

　　Compact footprint with 37 mm pitch spacing.The 37 mm center-to-center spool spacing allows multiple SD5 sections to be mounted in tight equipment enclosures,a critical advantage in metallurgical and marine applications where space is constrained.The G3/8”BSP ports are standardized across the series,reducing fitting inventory requirements.

　　Applications

　　Metallurgical hydraulic systems:Provides directional control for furnace door actuators and material handling cylinders,operating reliably within 315 bar pressure rating in high-ambient-temperature mill environments(tested to ISO 4406 contamination level 19/16).

　　Marine hydraulic systems:Delivers corrosion-resistant operation(housing:special cast iron,NBR seals)for winch controls and hatch actuators,with operating temperature tolerance from-15°C to+80°C covering tropical and cold-sea deployments.

　　Construction equipment:Enables precise boom and bucket control on small front loaders and truck-mounted cranes,with manual lever actuation force under 200 N reducing operator fatigue during extended shifts.

　　Agricultural machinery:Powers implement lift cylinders and steering functions on harvesters and balers,with rated flow of 45 L/min matching the hydraulic demand of mid-range tractors(40-80 HP).

　　Log splitters and material handling:Controls single-acting or double-acting cylinders with spring-return-to-center spool configuration,achieving cycle times within 1.5 seconds under full flow.

　　Selection Guidance

　　Suitable for:Open-center hydraulic systems requiring manual directional control of one actuator with flow demand up to 45 L/min at pressures up to 315 bar.

　　Suitable for:Applications where compact envelope(37 mm pitch)and monoblock construction are preferred over sectional valves due to space constraints.

　　Suitable for:Equipment operating in ambient temperatures from-40°C to+60°C with mechanical control,including outdoor construction and marine applications.

　　Not recommended for:Systems requiring flow exceeding 45 L/min or pressures above 315 bar.For higher flow requirements(e.g.,80 L/min),consider the Walvoil SD8 series or alternative valves with larger port sizing.

　　Not recommended for:Electro-hydraulic proportional control applications.The SD5/1-P is a manual on/off directional valve;for variable flow control or proportional actuation,select a proportional valve with integrated electronics.

　　Not recommended for:Closed-center hydraulic systems requiring load-sensing functionality.The SD5 series supports open and closed center configurations,but load-sensing variants require specific ordering codes(not available in base SD5/1-P model).

　　FAQ

　　1.What hydraulic fluid types and viscosity grades are compatible with the Walvoil SD5/1-P?

　　Mineral base oil with viscosity between 15 and 75 mm²/s(cSt)at operating temperature.The factory performance data is measured with ISO VG 46 mineral oil at 40°C;NBR seals are compatible with standard mineral oils,while FPM seals are required for phosphate esters or high-temperature fluids up to 100°C.

　　2.What is the maximum operating pressure and flow rate for the parallel circuit configuration?

　　315 bar at 45 L/min for parallel circuit type SD5/1-P.For series circuit configurations(SD5/1-S),maximum operating pressure is reduced to 250 bar at the same flow rate.Do not exceed 25 bar return line pressure.

　　3.What are the ambient and fluid temperature limits for reliable operation?

　　Fluid temperature range is-15°C to+80°C with NBR seals.Ambient temperature with mechanical(manual lever)control ranges from-40°C to+60°C;if equipped with electric devices,the ambient range narrows to-20°C to+60°C.For applications consistently above 80°C fluid temperature,specify FPM seals(factory order option).

　　4.How does the SD5/1-P differ from the SD5/1-N and SD5/1-D variants?

　　SD5/1-P uses parallel circuit(full pressure to all sections),SD5/1-N has no carry-over capability(terminates flow at the valve),and SD5/1-D includes a carry-over port for power beyond applications.All three share the same 315 bar pressure rating.For systems requiring series flow priority,specify SD5/1-S(rated 250 bar).

　　5.What installation and maintenance procedures are recommended for this valve?

　　Inspect every 6 months for external leaks and lever box seal integrity;do not use high-pressure wash directly on the valve to prevent water ingress.Change hydraulic fluid every 1000 operating hours and maintain filtration to NAS 1638 Class 10.The main relief valve is factory-set between 50 and 220 bar—adjust only with a calibrated pressure gauge