SOLENOID VALVE |
Solenoid
valve is a two or three way industrial valve which is energized
via AC or DC electrical power, and which controls the flow of
various fluid lines. They are made of coil, core, tube and the
body. The control of the flow line is provided by the movement
of the core, which is generated by the electromagnetic force on
the coil when it is energized.
olenoid valves are divided into two groups as per their
operating positions. The valves which open a closed line when
the coil is energized are called Normally Closed (N.C.), and the
valves which close an open line when the coil is energized are
called Normally Open (N.O.) |
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Direct Action Solenoid Valves |
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When the coil is energized an electromagnetic force is generated
and this force pulls the plunger to the fixed core. The plunger
opens (Normally Closed type) or closes (Normally Closed type)
the orifice through which the flow occures between valve inlet
and outlet. At the surface at which the plunger faces the
orifice is made leak-tightness is provided with the seal fitted
on the plunger. Since this seal contacts with the fluid flowing
through the valve it is extremely important to choose the
correct sealing material. Direct action solenoid valves operate
depending only on the coil force, so that they can operate even
if the line pressure is 0 Bar. For the same reason operating
pressure decreases as the orifice diameter increases. In GEVAX
direct action solenoid valve series, the orifice ranges between
1,5 mm and 6 mm while the pressure changes between 0 and 40 Bar.
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Pilot Operated Solenoid Valves |
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This type
operates on the basis of creating two pressure chambers in the
body with a diaphragm, and controlling the pressure difference
between these two chambers. Once the fluid is applied, both
sides (upper and lower sides) of the diaphragm are pressurized.
Since the pressure on the upper side is bigger, the diaphragm
closes the main flow orifice. In the normally closed pilot
operated type, when the coil is energized the pilot orifice,
which is connected with upper chamber, is opened to outlet; once
the pressure balance on the diaphragm is spoilt, main flow
orifice opens and flow occures. Because this type operates on
the basis of pressure difference, the difference between inlet
and outlet pressures of the valve must be minimum 0,5 Bar. If
not, flow does not occure through the valve. Since solenoid
valve doesn't operate as check valve the fluid flows back in
case of backward pressure. In such cases it is necessary to
install a check valve after the solenoid valve. |
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TERMS USED |
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Maximum Operating Pressure Differential |
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The maximum
pressure difference between inlet and outlet of the valve when
the valve is closed.
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Minimum Operating Pressure Differential |
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The minimum
pressure difference between inlet and outlet of the valve when
the valve is closed.
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Test Pressure |
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The
pressure which is applied during test of solenoid valves.
According to EN 12266-1:2003 if the test fluid is liquid, the
test pressure shall be minimum of 1,5 times the allowable
pressure at room temperature. |
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Operating
Temperature
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The
temperature range at which the valve can normally operate. |
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IMPORTANT REMARKS |
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Coil is one of the most
critical parts for the valve to have a long life cycle. It is very important to
use correct protection and insulation coil according to the application. The
voltage level and type (AC/DC) must be taken into consideration. GEVAX solenoid
valves are provided with proven quality world-famous coils
The minimum or maximum
pressure levels of the line or the system is very important for the selection of
appropriate valve. Inappropriate selection causes shorter life cycle.
The specifications of the
media to be applied must be considered. If not, internal valve parts may be
subject to excessive corosion.
Temperature of the media
must be taken into account
Solenoid valve must be
fitted on the line in a way that the arrow on the body and the flow are in the
same direction.
Since solenoid valve
doesn't operate as check valve the fluid flows back in case of backward
pressure. In such cases it is necessary to install a check valve after the
solenoid valve
The line to fit the valve
should be free of dirts and particles
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CODE SYSTEM |
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An
easy-to-understand code system is being used for GEVAX solenoid
valves, which indicates the functional crtiterion playing role
in valve selection. Details of code system is shown below:
NOTE: The number added at the end of the code
after " / " means pressure differentiation in the same physical structure while
the letter “M” added at the end shows that the valve has manual
by-pass system. |
