Brochure

Maximum Operating Pressure Differential
The maximum pressure differential against which
a solenoid valve can open is generally abbreviated
MOPD. This is illustrated in Figure 4.
MOPD ratings are established at 85% of rated voltage
and with a hot coil after its maximum temperature is
reached. For any given valve and coil design, the fac-
tors that effect MOPD are voltage deviation and coil
temperature.
Synthetic Seating
Introduced by Sporlan in 1947, synthetic seating
provides permanent seat tightness. Our experience in
the use of these superior seating materials provides a
reliable basis for durable construction best suited for
various applications.
Solenoid Coil
The interchangeability of solenoid coils is necessarily
limited by considerations of the varying requirements
of power and plunger movement. Nevertheless, only
three coil sizes are required for the extensive line of
Sporlan Solenoid Valves. Each coil is interchangeable
between a number of valves within a given size range.
Maximum Rated Pressure
Don’t confuse the MOPD rating of a valve with the
maximum rated pressure. The rated pressure of a
solenoid valve is a design specification indicating the
maximum pressure under which the valve should be
applied. Actually, the valve must be able to withstand
three times its maximum rated pressure and pass fa-
tigue cycle tests, to qualify for listing by Underwriters’
Laboratories.
Manual Lift Stem
Occasionally, circumstances require that a solenoid
valve be opened independently of the electrical power.
Therefore, a manual lift stem is available on all valves
from the B6 and E6 series up through the MA50 series.
315 psi
INLET
15 psi
OUTLET
Page 22 / Bulletin 30-10
General Sporlan Solenoid Valves
open, the disc is held off the seat by the pressure dif-
ference across the port. When the coil is de-energized,
the stem and plunger assembly drops, due to gravity
or the kick off spring, and closes the pilot port. As
shown in D the pressure above the disc is no longer
vented to the downstream side of the valve. Fluid flow
and pressure drop causes the pressure above the disc
to be higher than below the disc, and the disc drops,
closing the main port. In some valves the plunger is
spring loaded and does not rely on gravity to close.
All Sporlan Solenoid Valves except the A3, E3, W3,
MA5A3 and 180 SPC are pilot operated and employ
either the floating disc, floating piston or floating
diaphragm construction. The pilot operated valves
require a very low, 1 psi, pressure differential for full
operation.
Normally Open Solenoid Valves operate very
similar to the normally closed type. The system pres-
sure is utilized to open and close these valves.
The major difference in the normally open construction
is that with the coil de-energized, a spring is used to
push the stem and plunger assembly upward holding
the pilot port open. This then allows the disc to rise,
because of the pressure difference between the bottom
and top of the disc, and permits flow to take place.
When the coil is energized, the stem and plunger as-
sembly is pulled DOWN, closing the pilot port. The
pressure on top of the disc then equalizes with the
incoming pressure and the disc moves down closing
the main port. The valve will remain closed as long as
the coil is energized.
Direct-Connected Piston Assemblies, with the
stem and plunger mechanically connected to the pis-
ton, are used on applications where the valve must be
sized for very small pressure drop, such as on suction
lines. While the pilot operated principle is still used to
open the valve, the magnetic pull of the coil is utilized
to hold the piston open, preventing possible pulsa-
tions. A disadvantage of the direct-connected type is
the case where dirt prevents free piston movement and
the plunger is unable to center itself in the coil. This
will cause overheating of the coil and the danger of
coil burnout is present. The “floating piston or disc”
type permits independent operation of the plunger to
allow a complete magnetic circuit regardless of the
piston’s position and thereby eliminates the possibility
of coil burnout due to restricted piston or disc move-
ment. For additional information, see Page 27, Suction
Line Service.
Figure 4
Design
MOPD
300 psi