Danfoss EV251B Data sheet

Data Sheet

Solenoid valve
Type EV251B

Compact servo operated with assisted lift for general purpose

EV251B with assisted lift is especially suitable
for applications such as closed systems with
low and uctuating pressure conditions or
open systems with dierential pressure down
to 0 bar.

EV251B valves are supplied complete, including
coil and plug.

Features and versions

• For water, oil, compressed air and similar
neutral media

• Clip on coil

• Ambient temperature: Up to 80 °C

• Coil enclosure: IP65

AI236986442833en-000901

Features

EV251B

Body material

Brass

DN [mm]

10-22

Connection

G3/8'' - G1''

Sealing material

NBR

Function

NC

Kv [m3/h]

1.5-3.5

Dierential pressure range [bar]

0-10

Temperature range [°C]

-10-90

Solenoid valve, type EV251B

1 Portfolio overview

Table 1: Portfolio overview

© Danfoss | Climate Solutions | 2021.06 AI236986442833en-000901 | 2

1

234567899.1

9.2

Coil

Armature

Closing spring

Valve plate

Pilot orice

Diaphragm

Main orice

Equalizing orice

Assist

Assist spring

Assist connector

Solenoid valve, type EV251B

2 Function

2.1 Function NC

Coil voltage disconnected (closed)

When the supply voltage to the coil (1) is disconnected, the valve plate (4), is pressed down against the pilot orice
(5), by the closing spring (3). The pressure across the diaphragm (6), is built up via the equalizing orice (8). The
diaphragm closes the main orice (7), when the pressure above the diaphragm exceeds the inlet pressure below
due to the larger diameter of the upper side and the compression of the closing spring (3). The valve will be closed
for as long as the voltage to the coil is disconnected.

Coil voltage connected (open)

When the voltage is applied to the coil, the armature (2), and the valve plate (4), are lifted clear of the pilot orice (5).
If there is a dierential pressure across the valve, the pressure across the diaphragm (6), drops because the pilot
orice is larger than the equalizing orice. This causes the diaphragm to be lifted clear of the main orice (7). If there
is no dierential pressure across the valve, the armature (2) draws the diaphragm (6) clear of the main orice (7),
using the assist spring (9.1) and assist connector (9.2). The valve will be open for as long as there is voltage to the
coil.

Figure 1: Function NC

© Danfoss | Climate Solutions | 2021.06 AI236986442833en-000901 | 3