Dungs Pressure switch LGW3A4 221590

The Dungs LGW3A4 pressure switch (SKU 221590) is an adjustable differential pressure switch for gas valves, suitable for gases of families 1, 2, 3, and neutral gases. It operates without auxiliary energy, using a diaphragm to actuate a microswitch based on pressure changes. The setting range is 0.4–3 bar, with a maximum operating pressure of 500 mbar. The body is aluminum die-cast, housing and switch are polycarbonate, membrane is NBK, and switching contacts are high purity silver. It has IP 54 ingress protection, ambient temperature range -15–70 °C, storage temperature -30–80 °C, and a measuring connection of Ø 9. The preset color is blue (standard) or yellow (execution Y), and it is set in vertical position at falling pressure. Approvals include CE-0085 AQ 0673 and CE0036.

Parts of this type are selected by matching the setting range, maximum operating pressure, and measuring connection size to the system requirements. The mounting position must be vertical for accurate falling pressure setting; deviations affect the switching point. Ensure the electrical rating and switching contact material are compatible with the control circuit. The pressure connection must match the existing fitting, typically Ø 9 mm.

Common failures include diaphragm rupture or leakage, leading to loss of pressure sensing and incorrect switching. The switch may fail to actuate or remain stuck, causing burner lockouts or improper gas valve operation. Check for visible damage, test the switch with a manometer, and verify the electrical continuity of the contacts.