Walvoil DPX Series: Pressure-Compensated Load-Sensing and Flow-Sharing Directional Valves

The Walvoil DPX Series is a family of post-pressure-compensated sectional directional valves built specifically for mobile applications, combining load-sensing (LS) with flow-sharing technology in a single platform. It covers flow rates up to 160 l/min (42 US gpm) at the working ports and is offered in three sizes — DPX050, DPX100, and DPX160 — with Standard, High Pressure (HP), and High Flow (HF) configurations depending on size.

What distinguishes the DPX Series from a conventional load-sensing valve is its patented compensator behaviour during flow saturation. The compensator holds the margin pressure as a constant pressure drop across the spool metering area, so flow to each workport depends only on spool position. When pump flow can't satisfy total demand, the pressure drop across all spools is reduced equally, so every active function slows proportionally instead of one movement starving another. The operator keeps control of all functions simultaneously, just at reduced speed. For OEM buyers specifying valves for series production, this is the core selling point: predictable multi-function control without oversizing the pump.

What is a flow-sharing directional valve, and how does the DPX Series implement it?

In a standard load-sensing system, when demand exceeds pump capacity the highest-load function tends to stall while lighter loads keep moving. Flow sharing changes that. In the DPX Series, because every spool sees the same pressure drop across its metering area, all flows are reduced in proportion during saturation. The governing relationship is dimensionless — flow is a function of metering area, pressure drop and oil density — but the practical outcome is simple: proportional speed reduction across the board, no loss of controllability.

This makes the DPX Series a "full flow-sharing" sectional valve rather than a basic LS valve, which matters for machines where two or three actuators move together — loaders, cranes, aerial platforms, and similar mobile equipment.

DPX Series sizes and key specifications

The three sizes share the same architecture but scale flow and pressure:

Shared working conditions across all sizes: mineral oil, fluid temperature range −20 °C to 100 °C (−4 °F to 212 °F), viscosity operating range 15–75 mm²/s, and a maximum contamination level of ISO 4406 19/18/15 (NAS 1638 class 9). The HP version is stackable with the standard version, which gives builders flexibility to mix pressure ratings within one valve bank.

For verified per-spool flow curves and section dimensions on a specific build, refer to the size-specific pages of the DPX catalogue [VERIFICARE: portata per sezione l/min on chosen spool].

How do you configure a DPX Series valve?

The DPX Series is sectional: an inlet section, one or more working sections, and an outlet section. Configuration depends on control type.

For mechanical, hydraulic, or electric controls, the valve uses standard inlet sections, working sections without pilot lines, and standard outlet sections. For electrohydraulic or mixed controls, working and outlet sections require pilot lines, and there are positioning rules: two-side electrohydraulic sections must sit after one-side sections, and electrohydraulic sections must be grouped toward the outlet. To insert a manual/hydraulic section between two electrohydraulic sections, a specific working-section kit able to cross the pilot line is required.

Available options that affect specification include an inlet section with unidirectional restrictor (for damping LS-line pressure peaks), working sections with priority features under saturation, and dedicated spools for customised flows, back pressures, or pressure control. These are typically quoted through Walvoil Sales for non-standard builds.

Why the DPX Series suits series production and OEM mobile applications

For OEM buyers, the value-for-money case rests on three things. First, energy efficiency: on a closed-centre system the pump produces only the flow and pressure the actuators require, reducing power loss and heat. Second, compact flow capacity: the flow-passage design allows high P and T flow rates within standard valve dimensions, so a builder doesn't move up a frame size to get throughput. Third, configurability without redesign: the sectional architecture and stackable HP sections let one valve platform cover a range of machine variants in series production.

The DPX Series is made in Italy by Walvoil S.p.A. (Reggio Emilia), part of Interpump Group, with a global service and sales network — relevant for OEMs supplying machines into multiple markets.

FAQ

What flow rate does the Walvoil DPX Series handle?

Up to 160 l/min (42 US gpm) at the working ports on the DPX160, with the DPX050 and DPX100 rated at 50 l/min and 90 l/min respectively (standard versions, at 14 bar margin pressure).

What's the difference between load sensing and flow sharing on the DPX Series?

Load sensing matches pump output to the highest load demand. Flow sharing adds proportional control under saturation — when demand exceeds pump flow, all DPX functions slow proportionally instead of the heaviest load stalling.

What maximum pressure can the DPX Series withstand?

Standard DPX050 reaches 300 bar at the P inlet and 350 bar at the A/B ports. HP and HF versions of the DPX100 and DPX160 reach up to 380 bar (inlet) and 420 bar (working ports).

Is the DPX Series suitable for closed-centre systems?

Yes. On a closed-centre circuit it produces only the flow and pressure the actuators require, which reduces energy loss and heat — a key advantage for mobile machinery.

Can high-pressure and standard sections be combined in one valve?

Yes. The High Pressure (HP) version is stackable with standard sections, letting builders mix pressure ratings within a single valve bank.

Where is the DPX Series manufactured?

The DPX Series is made in Italy by Walvoil S.p.A. in Reggio Emilia, part of Interpump Group, with a worldwide sales and service network.