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6. Maintenance and inspection
6.1 Daily inspection
(1) Check the vibration, noise, current value,
etc. of the fan.
If there is any unusual condition, it may be
a sign of failure; therefore, take the
appropriate measures as soon as possible.
For this purpose, it is recommended to
keep an operation log.
(2) If strong vibrations occur, stop operation
and inspect improper duct connections,
tightening of the installation bolts and
foundation bolts, and check for
accumulation of dust on the impeller and
damage to the bearings.
If the vibration is within the range specified
as "Good" in JIS B 8330, it is considered
normal (see the figure on the right).
If a vibration insulating device is installed
on the fan, vibration of the fan itself
becomes slightly stronger although the
vibration is not transmitted to the
foundation. In such a case, a vibration
lower than the broken line is considered
normal.
(3) In addition to vibrations, noise is an
important factor in judging the operating
condition.
If you hear a metallic sound possibly made
by contact into the rotor, stop the operation immediately.
(4) Bearings generate noise even in normal condition.
Although it is difficult to identify an abnormal noise because bearings produce complicated
noise, try and detect it at an early stage with careful attention.
6.2 Periodic inspection
Warning
Before carrying out the inspection of the fan, be sure to turn off the
main power. Otherwise the fan may suddenly start up during
automatic operation etc., exposing personnel to great danger.
Carry out the periodic inspection at least once a year.
The periodic inspection items include the following points, in addition to the daily inspection
items.
(1) Check if there is no extra backlash in the coupling between impeller and motor shaft.
(2) Inspect the impeller and the shaft for corrosion and wear.
(3) Clean the inside of the fan, and apply anti-corrosive agent or otherwise repair the part.
(4) Check that the insulation resistance of the motor has not decreased. At least 1MΩ is
required.
n - Rotation (mim
-
)
Acceptable vibration range
a - Total amplitude (μm)
With vibration isolator
10mm/s
Acceptable
Excellent
Good
(On the motor casing or the bearing housing)
Unacceptable
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