NCF fan
2.2.4 Operating speed risks
CAUTION! Risk of equipment damage
• Do not exceed the maximum rotation speed
indicated by Nederman.
• Do not use ON-OFF operating cycles unless
expressly approved by Nederman.
• Do not subject the fan to thermal gradients
greater than 3°C/minute.
• A condition of overspeed, even for a limited
time, may cause irreversible damage and cre-
ate situations of extreme risk hazards. The
maximum speeds indicated by Nederman
must never be exceeded.
• The manufacturer must always be contacted
in the case of use of a supply frequency oth-
er than the original design frequency. Do not
proceed until authorized.
• In the case of fan operation with a variable
speed cycle of less than 30 minutes, this
cycle must be submitted to approval by the
Nederman Technical Office, which will give
its approval and notify the consequent re-
duction of maintenance intervals and the fan
life span.
• Inverting the fan rotation direction or start-
ing it with the impeller turning in the op-
posite direction may cause breakage of the
blades and/or the impeller hub, with the risk
of ejection of metal parts.
• Resonance phenomena at low frequencies
may cause damage to the structure.
Operating speeds greater than those envisaged by
the fan design can create conditions of risk due to the
reduction of the operative life span of moving parts.
In case of faults or malfunctions, overspeed condi-
tions may be created due to:
• Errors in the control logic system
• Short circuits on monitoring components
• Driver or inverter malfunctions
• Mechanical breakage of components, and in particu-
lar on encoder
During normal operation, conditions of overspeed at-
tributable to the drive system or motor may occur,
in particular if the fan is supplied “with shaft only” or
with motor “without drive system”.
The use of a supply frequency different from the ori-
ginal design frequency affects all fan characteristics.
The modification of conditions of use requires a com-
plete revision of the technical information sheet of
the fan.
In the case of use at varying fan speeds or with fre-
quent starting and stopping during operation, rotating
organs are subject to mechanical stresses that may
affect their operative life span.
If the rotation direction of a fan must be inverted, or if
it must be restarted, this must be done only when the
impeller is in the rest position (total standstill).
Operation at a speed significantly lower than up to
40% of nominal speed (unless otherwise specified
by Nederman) may affect the cooling of the motor
and bearings, with possible malfunctions due to high-
er temperatures. For electrical components, the user
and installer are advised to provide adequate protec-
tion for the drive system or motor, with the use of
heat detection capsules if possible, and also using a
servo-ventilated motor if necessary.
Resonance phenomena in the structure must be
avoided. These may emerge at specific rotation
speeds, and may cause damage to the structure.
2.2.5 Noise emission risks
WARNING! Risk of personal injury
A person may receive injuries as a result of:
• Being dragged between a moving part and
a fixed part, for example a impeller and the
casing or some other fixed part of the fan.
• Being dragged into the fan through the air in-
take, with consequent contact with the shaft
or impeller.
• Contact with a moving part, such as the im-
peller.
• Ejection from the fan exit of fragments deriv-
ing from the introduction of residual solids or
liquids extraneous to the process, or deriving
from the suction environment.
• An object drawn into the fan mouth and ejec-
ted at high speed from the fan intake or exit.
• Structural defects of fan components.
• Contact with fan surfaces at dangerous tem-
peratures, for example below -20°C or higher
than +50°C.
• When working with hot fluids, there may
be losses of jets of hot fluid from the trans-
mission shaft hole that may cause burns or
scalds.
• The potential harmfulness of the fluid being
moved or the presence of substances that in
case of leaks may be hazardous (toxic and/or
inflammable).
• A hazard deriving from motor overspeed,
which may cause the breakage of machine
parts.
• The intake of air at abnormal temperatures
higher than those recommended may cause
structural deformations, malfunctions and
hazards.
Since the noise emitted by a fan can be influenced by
external factors that can affect the overall noise level,
such as:
EN
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