R900424279 DBDS20P1X/400 Rexroth hydraulic valve German original relief valve

FAQ:

FAQs for Rexroth DBDS20P1X/400 Direct-Acting Relief Valve

1. Q: This valve is rated for 400 bar. How do I adjust it to a specific pressure, and is the setting stable?

   A:​ The pressure is adjusted via an external screw with a lock nut. Use a calibrated pressure gauge to monitor system pressure while making fine adjustments. After reaching the desired setting, the lock nut must be securely tightened to prevent the setting from drifting due to vibration. The valve is designed for stable settings, though changes in temperature and flow can cause slight variation within the rated hysteresis band.

2. Q: What is the main difference between the "/200" and "/400" model suffixes?

   A:​ The suffix (e.g., /200, /400) indicates the maximum adjustable pressure​ of the valve. The DBDS20P1X/400​ can be set to a maximum of 400 bar, while the DBDS20P1X/200​ is limited to 200 bar. The internal spring and possibly other components are calibrated for the respective pressure range. Do not exceed the maximum pressure rating indicated by the suffix.

3. Q: What does "direct-acting" mean, and how does it affect performance?

   A:​ "Direct-acting" means the system pressure acts directly on the valve's poppet or spool against a spring force. When the set pressure is exceeded, the valve opens directly. This design offers a very fast response time, making it ideal for pressure spike protection. However, as flow increases, the pressure required to keep the valve open also increases slightly—a characteristic known as pressure override.

4. Q: The valve is making a loud, chattering noise. What does this indicate?

   A:​ A chattering or buzzing noise typically indicates the valve is operating near its cracking point with unstable flow. This can be caused by: 1) The pressure setting being too close to the normal system operating pressure, 2) A rapid pressure pulsation from the pump, or 3) Insufficient system damping (e.g., a small accumulator). Try increasing the margin between the operating pressure and relief setting, or install a small pulsation damper.

5. Q: Can this valve be used as a pressure reducing valve or a sequence valve?

   A: No. This valve is designed solely as a pressure relief/limiting valve.​ It is a two-port valve (P to T) that opens to tank when the inlet pressure exceeds the set point. A pressure reducing valve is a three-port valve that maintains a lower, constant secondary pressure. A sequence valve is used to direct flow to a secondary circuit after a set pressure is reached. Their functions and internal designs are different.