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Design / Selection

3. Surge voltage suppressor

1) The surge voltage suppressor built into the valve is intended to

protect the output contacts so that the surge generated inside
valve does not adversely affect the output contacts. Therefore, if
an overvoltage or overcurrent is received from an external
peripheral device, the surge voltage protection element inside
the valve is overloaded, causing the element to break. In the
worst case, the breakage causes the electric circuit to enter
short-circuit tatus. If energizing continues while in this state, a
large current flows. This may cause secondary damage to the
output circuit, external peripheral device, or valve, and may also
cause a fire. So, take appropriate protective measures, such as
the installation of an overcurrent protection circuit in the power
supply or a drive circuit to maintain a sufficient level of safety.

2) If a surge protection circuit contains nonstandard diodes, such

as Zener diodes or varistor, a residual voltage that is in
proportion to the protective circuit and the rated voltage will
remain. Therefore, take into consideration the surge voltage
protection of the controller. In the case of diodes, the residual
voltage is approximately 1V.

4. Surge voltage intrusion

With non-polar type solenoid valves, at times of sudden

interruption of the loading power supply, such as emergency

shutdown, surge voltage intrusion may be generated from loading

equipment with a large capacity (power consumption), and a

solenoid valve in a de-energized state may switch over (see

Figure 1).

When installing a breaker circuit for the loading power supply,

consider using a solenoid valve with polarity (with polarity

protection diode), or install a surge absorption diode between the

loading equipment COM line and the output equipment COM line

(see Figure 2).

Operation in a low temperature condition

It is possible to operate a valve in extreme temperature, as low
as -10

Take appropriate measures to avoid freezing of

drainage, moisture etc. in low temperature.

Operation for air blowing

When using a solenoid valve for air blowing, use an external
pilot type.
Use caution because the pressure drop caused by the air
blowing can have an affect on the internal pilot type valve when
internal pilot type valves and external pilot type valves are used
on the same manifold.
Additionally, when compressed air within the pressure range of
the established specifications is supplied to the external pilot
type valve’s port, and a double solenoid valve is used for air
blowing, the solenoids should normally be energized when air is
being blown.

7. Mounting orientation

Mounting orientation is free.

Initial lubrication of main valve

The following initial lubricant has already been applied to the

main valve.

• Rubber seal, spool valve: Grease

Please consult with SMC, as there are some standard valve

products that use fluorine grease for food processing equipment

(NSF H-1).

9. For the pilot EXH (PE) port

If the solenoid valve and the manifold’s pilot EXH (PE) port is
restricted extremely or blocked, abnormal operation of the
solenoid valve may occur.

SX3000/5000/7000 Series