Safety valve DANFOSS 6422571 DN20, spring-loaded overpressure relief valve, DN20 connection

DANFOSS 6422571 is a spring-loaded safety valve with a DN20 connection designed to protect pressurised systems by releasing excess pressure at a preset setpoint. Intended for heating, hot water and industrial pressure systems, the valve ensures controlled pressure relief to avoid component damage and maintain operational safety. The compact DN20 fitting and spring mechanism provide reliable operation across typical installation conditions.

Advantages

The spring-loaded design delivers consistent opening behaviour at the set pressure and ensures quick response to overpressure events. A DN20 connection allows compatibility with standard pipework and fittings used in domestic and light industrial systems. Constructed with materials suitable for media commonly found in heating and hot water systems, the valve offers corrosion resistance and stable performance under repeated cycles.

Suitable for

• Residential and commercial heating systems
• Hot water supply installations
• Closed-loop industrial pressure systems requiring overpressure protection
• Piping and equipment with DN20 connections

Key specifications

• Valve type: spring-loaded overpressure relief valve
• Connection size: DN20
• Function: opens at preset overpressure to release excess media
• Application: suitable for steam-free liquid and gaseous media common in heating and hot water systems
• Operating principle: mechanical spring actuation for predictable opening

How to use

Install the safety valve on the pressure vessel or pipeline at a location recommended by system designers, ensuring the DN20 connection matches the existing piping. Set and verify the opening pressure according to system requirements and applicable standards before commissioning. Ensure correct orientation and provide adequate discharge piping if required by local regulations to safely convey released media away from personnel and equipment. Regular inspection and maintenance should be performed to confirm free movement of the spring mechanism and absence of blockages.

Usage recommendations

Verify compatibility of the valve materials with the system media and operating temperatures. Follow applicable codes and manufacturer guidance for setting, installation torque and discharge arrangements. Schedule periodic functional tests and visual inspections to ensure reliable performance and replace the valve if signs of corrosion, leakage or mechanical wear are observed.