The Z2DB 6 series pressure relief valve is a sandwich-plate design engineered for the limitation of system pressure within hydraulic circuits, conforming to ISO 4401-03-02-0-05 mounting patterns. Designed for stackable configurations, this valve utilizes a pilot-operated poppet mechanism to provide stable pressure regulation across varying flow rates, effectively mitigating the pressure overshoot common in direct-acting designs. The valve body houses a pilot stage and a main stage poppet, where the pilot stage controls the opening pressure and the main stage manages the bulk flow, ensuring high-frequency response and minimal hysteresis under static and dynamic load conditions.
For complete selection guidelines and cross-reference documentation on this product line, please consult our Rexroth equivalent hydraulic valves guide.
Technical Specifications and Performance Parameters
The Z2DB 6 is designed for integration into modular manifold systems where space constraints necessitate compact, vertical stacking. The following table outlines the primary operational parameters for the standard series.
| Parameter | Specification |
|---|---|
| Interface | ISO 4401-03-02-0-05 |
| Max Operating Pressure | 315 bar |
| Max Flow Rate | 60 L/min |
| Pressure Stages | 50, 100, 200, 315 bar |
| Fluid Temperature Range | -30°C to +80°C |
| Viscosity Range | 10 to 800 mm²/s |
| Mounting Orientation | Optional |
Hydraulic Characteristics and Operational Stability
The Z2DB 6 operates on the principle of a pilot-controlled poppet. When the system pressure at the P-port exceeds the force exerted by the pilot spring, the pilot poppet lifts, creating a pressure drop across the orifice in the main spool. This pressure differential causes the main poppet to open, diverting excess flow to the tank (T-port).
Engineers must account for the pressure-flow characteristic curve, as the cracking pressure is subject to slight variations based on the viscosity of the hydraulic fluid. To maintain the rated pressure stability, the pilot stage requires a consistent flow path; therefore, the T-port must be connected to a low-pressure return line to prevent backpressure from influencing the pilot setting.
Contamination Control and ISO 4406 Standards
Hydraulic system longevity is fundamentally linked to fluid cleanliness. The Z2DB 6, like all pilot-operated valves, is susceptible to spool silting and pilot orifice clogging if particulate matter is present.
- Cleanliness Requirements: To ensure reliable operation and prevent premature wear of the poppet-seat geometry, the hydraulic fluid must meet a minimum cleanliness class of 20/18/15 according to ISO 4406.
- Filtration: It is recommended to utilize a return-line filter or pressure-line filter with a beta ratio of β(c) ≥ 1000 to maintain these levels, particularly in systems prone to metallic wear debris.
Seal Elastomer Compatibility
The selection of seal materials is critical for chemical compatibility and thermal stability. The Z2DB 6 is typically supplied with either NBR (Nitrile Butadiene Rubber) or FKM (Fluorocarbon/Viton) seals.
- NBR (Nitrile): Suitable for standard mineral-oil-based hydraulic fluids (HLP/HLPD). It provides excellent mechanical properties but is limited in high-temperature applications exceeding 80°C.
- FKM (Viton): Mandatory for applications involving synthetic esters, phosphate esters, or high-temperature environments. FKM offers superior resistance to chemical degradation and aging, though it requires careful monitoring during installation to prevent pinching or shearing of the O-ring profiles.
Compliance with DIN 24340 and ISO 5781 standards ensures that the Z2DB 6 remains interchangeable with other industry-standard modular valves, facilitating maintenance and system upgrades in existing hydraulic power units.