Precautions On Design/Selection - SMC Networks VQ7-6 Series Operation Manual

VQ7-6/7-8 Series
5 Port Solenoid Valve / Precautions 1
Be sure to read before handling.
Design / Selection
Warning
1. Confirm the specifications.
Products represented in this manual are designed only for use
in compressed air systems (including vacuum).
Do not operate at pressures or temperatures, etc., beyond the
range of specifications, as this can cause damage or
malfunction. (Refer to the specifications.)
We do not guarantee against any damage if the product is
used outside of the specification range.
2. Actuator drive
When an actuator, such as a cylinder, is to be driven using a
valve, take appropriate measures (cover installation or
approach prohibition) to prevent potential danger caused by
actuator operation.
3. Intermediate stops
For 3-position closed center or double check valve type, it is
difficult to make a piston stop at the required position
accurately due to the compressibility of air.
Furthermore, since valves and cylinders are not guaranteed
for zero air leakage, it may not be possible to hold a stopped
position for an extended period of time.
Please contact SMC if it is necessary to hold a stopped
position for an extended period of time.
4. Effect of back pressure when using a
manifold
Use caution when valves are used on a manifold, because an
actuator may malfunction due to back- pressure.
For 3-position exhaust center valve or single acting cylinder,
take appropriate measures to prevent malfunction by using it
with an individual EXH spacer assembly (VV71-R-).
5. Holding of pressure (including vacuum)
Since the valves are subject to air leakage, they cannot be
used for applications such as holding pressure (including
vacuum) in a pressure vessel.
6. Not suitable for use as an emergency shutoff
valve, etc.
The valves listed in this manual are not designed for safety
applications such as an emergency shutoff valve. If the valves
are used for the mentioned applications, additional safety
measures should be adopted.
7. Release of residual pressure
For maintenance purposes install a system for releasing
residual pressure. Especially in the case of 3-position closed
center valve or double check valve type, ensure that the
residual pressure between the valve and the cylinder is
released.
8. Double solenoid type
When using the double solenoid type for the first time,
actuators may travel in an unexpected direction depending on
the switching position of a valve. Implement measures to
prevent any danger from occurring when operating the
actuator.
9. Ventilation
Provide ventilation when using a valve in a confined area,
such as in a closed control panel. For example, install a
ventilation opening, etc. in order to prevent pressure from
increasing inside of the confined area and to release the heat
generated by the valve.
10. Extended periods of continuous energization
If a valve will be continuously energized for an extended
period of time, the temperature of the valve will increase due
to the heat generated by the coil. This will likely adversely
affect the performance of the solenoid valve and any nearby
peripheral equipment. Therefore, when it is continuously
energized or the energized period per day is longer than the
de-energized period use a DC specification valve.
For applications such as mounting a valve on a control panel,
incorporate measure to limit the heat radiation so that it is
within the operating temperature range. For example, the
temperature will be high when a 3 station manifold.
If conflicting instructions are given in the "Specific Product
Precautions" or on the "How to Order Valves" page, give them
priority.
11. Do not disassemble the product or make any
modifications, including additional
machining.
Doing so may cause human injury and/or an accident.
12. Resumption after a long period of holding time
When resuming operation after a long period of holding time,
there are cases in which, regardless of whether the product is
in an ON or OFF state, there is a delay in the initial response
time due to adhesion. Conducting several cycles of running-in
operation will solve this problem. Please consider
implementing this before resumption.
Caution
1. Precautions for 2-position double solenoid
valves
If a double solenoid valve is operated with momentary
energization, it should be energized for at least 0.1 seconds.
However, depending on the piping conditions, the cylinder
may malfunction even when the double solenoid valve is
energized for 0.1 seconds or longer. In this case, energize the
double solenoid valve until the cylinder is exhausted
completely.
2. Leakage voltage
Take note that the leakage voltage will increase when a
resistor is used in parallel with a switching element or when a
C-R circuit (surge voltage suppressor) is used for protecting a
switching device because of the leakage voltage passing
through the C-R circuit. The suppressor residual leakage
voltage should be as follows.
DC coil 3% or less of rated voltage
AC coil 20% or less of rated voltage
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