Air pressure switch
dreizler A 3001 E - 18.12.2015 | A 2029 - 2.14 | EN - 11.11.2014
130
40 Air pressure switch
Air pressure switch are designed to monitor air supply and are used as overpressure, underpressure, and
pressure differential switches. The membrane controlled measuring device monitors even the smallest
pressure differences, and opens the power circuit to the gas burner if the value falls below the preset min-
imum. The positions of the air pressure switch is checked during burner start-up.
NOTICE:
The installation of an air pressure switch is mandatory in accordance with EN 676.
NOTICE:
For more information about type-specific component characteristics, please see relevant manufacturer
documentation.
40.1 Function of the air pressure switch
Air pressure switch LGW...A4 , Dungs
The air pressure switch reacts when pressure rises or falls. It actuates a microswitch, which is designed as
a changer. Switching pressure is set by way of a screw or a handwheel against a spring force.
Some air pressure switches are equipped with test buttons or a test terminal for function checks during op-
eration.
When a button is pressed (both buttons for differential pressure), or the rubber cap is removed from the test
terminal, the switch actuates a switching function.
Fig. 40-1 Section air pressure switch LGW...A4
Fig. 40-2 Layout of air pressure switch LGW...A4
Switching function LGW...A4
At pressure increase:
1 NC opens, 2 NO closes.
At pressure decrease:
1 NC closes, 2 NO opens.
