Product Overview

© Danfoss | DCS (az) | 2017.12
7
8
+
+
+
–
+
–
Data sheet | Solenoid valves for water shut off and leak detection, Types EV220T, EV220W, EV220B, and EV228B
IC.PD.200.S1.02 | 21
Function
When – (minus) is supplied to the right terminal
pin and + (plus) to the left (see fig. a), the valve
plate is pressed down against the pilot orifice (4)
by the armature spring (2).
The pressure across the diaphragm (5) is built
up via the equalizing orifice (7). The diaphragm
closes the main orifice (6) as soon as the
pressure across the diaphragm is equivalent to
the inlet pressure. The valve will stay closed, until
the poles are switched (see fig. b).
Fig. a
Fig. b
Pos. no. Description
1 Coil
2 Armature spring
3 Valve plate
4 Pilot orifice
5 Diaphragm
6 Main orifice
7 Equalizing orifice
8 Permanent magnet
Switching poles
When + (plus) is supplied to the right terminal
pin and – (minus) to the left (see fig. b), the pilot
orifice (4) is opened. As the pilot orifice is larger
than the equalizing orifice (7), the pressure across
the diaphragm (5) drops and therefore it is lifted
clear of the main orifice (6). The valve is now
open for flow and will stay open as long as the
minimum differential pressure across the valve
is maintained, until the poles are switched back
(see fig. a).