R900423723 DBDS6K1X/100 Plug in overflow valve from Rexroth, Germany

FAQ - Frequently Asked Questions

Q1: What does the "/100" in the model number mean? Can it be adjusted to 200 bar?

A:​ No, it cannot.​ The "/100" indicates the valve is equipped with a spring for the 100 bar pressure stage. The DBDS6K series uses different springs to define pressure ranges (e.g., /25, /50, /100, /200, /315, /400). While the valve body is rated for 400 bar, the /100 model's spring is only designed for reliable adjustment up to about 100 bar. For higher pressures, you must select the corresponding high-pressure model (e.g., DBDS6K1X/200).

Q2: What are the critical installation considerations?

A:​ The most important factors are the cavity size and tightening torque.

• Cavity Must Match:​ A standard DBD NG6 (M28×1.5) cavity​ is required. An incorrect cavity will cause the valve to malfunction or leak.

• Tightening Torque:​ The recommended installation torque is 50±5 Nm​ (for pressure stages ≤ 200 bar). Excessive torque can damage the cartridge or seals, while insufficient torque can cause leaks.

Q3: Can the T port (tank port) handle backpressure?

A:​ Yes, but with a limit.​ The T port can tolerate backpressure, but this backpressure is added directly to the system pressure. For example, if the valve is set to 80 bar and the T port has 10 bar of backpressure, the actual relief pressure will be about 90 bar. Ensure the total pressure (set pressure + T port backpressure) does not exceed the valve's maximum operating pressure limit of 400 bar.

Q4: Why does the valve exhibit significant pressure overshoot or oscillation near the set point?

A:​ Direct-operated relief valves are prone to this at high pressures and high flows. Main causes include:

1. Excessive Flow:​ The NG6 valve's full-flow opening capability near 100 bar is limited. If the actual flow is close to 50 L/min, consider upgrading to an NG10 valve.

2. Unstable Tank Line Backpressure:​ Check if the T port return line is unrestricted and if the backpressure is stable.

3. Fluid Contamination:​ Dirt can cause the spool to stick, leading to sluggish pressure response.

Q5: Can it be used as the main system safety valve?

A:​ Yes, that is its primary purpose.​ The DBDS series is designed for pressure limitation and safety protection. It is typically installed at the pump outlet or in the main line to limit the maximum system pressure and prevent overload. The valve port remains closed (P→T blocked) until the system pressure reaches the set value, at which point it opens to divert excess flow to the tank.