Impeller; Fan Casing; Inspecting The Bearings; Permanently Lubricated Bearings (Y And S) - S&P CXRT Notice D'utilisation Et Entretien

Service and repair
concave shape. If wear is strong, the belt pulleys must
also be occasionally replaced with new ones.

4.5 Impeller

In order for the impeller to stay in balance dynamically,
dirt sticking to it must be removed. Imbalance will cause
extra vibration, resulting in, for example, greater stress
placed on the bearings. Cleaning should be done when
needed, but inspections should be carried out at least
once a year. A badly contaminated impeller reduces the
fan efficiency rate, thus increasing energy consumption.
Cleaning of the impeller can be done with a vacuum
cleaner, compressed air or by brushing. If dirt is greasy
and sits tight on the impeller, it must be cleaned with
a suitable detergent or solution.

4.6 Fan casing

Action is similar as with the impeller. Check also that
the impeller does not make any contact with the inlet
cone (especially with LB and HB fans).

4.7 Inspecting the bearings

In most cases, any flaws in the bearings can be detected
by listening. When the bearings are normal, they
generate a smooth and uniform sound. Loud and
squeaking noises or other abnormal sounds indicate that
the bearings are worn out. A squeaking noise can also
be caused by insufficient lubrication. Bearing cross-gaps
that are too small can cause a metallic noise. Dents on
the outer race of the bearing can cause vibrations, which
produce a soft and clear noise. Intermittent noises
indicate a defective rolling surface. Noises are produced
when the damaged spot hits the rolling surface. High
temperatures are usually a sign that the bearings are
running abnormally. Excessively high temperatures are
harmful to the grease and the bearing itself. Long term
operation at temperatures above 120°C can shorten the
useful life of the bearing. High bearing temperature may
be due to insufficient or excessive lubrication, impurities
in the grease, overloading, bearing damage or too small
a bearing cross gap. Even a slight temperature change
can be a sign of impaired operation if the operating
conditions have not changed. First filling or refilling with
lubricant will normally cause a rise in bearing
temperature, lasting one or two days. Monitor the
grease. A change of color or darkening is usually a sign
that there are impurities in the grease. Larger grains of
impurities can be detected by rubbing the grease
between the fingers. Check also the gaskets (e.g. V-ring)
and change them if necessary. In the following are
Table 4.3 Standard bearing types for GT-3 fans.
Impel-
ler
025 031 040
LF Y Y Y
LB - Y Y
HB - - S
Fan size
045 050 056 063
Y Y Y Y
Y Y Y Y
S S S S
detailed descriptions of the care of the bearing types
used. In Table 4.3 is a summary of bearings used in
different fans.

4.7.1 Permanently lubricated bearings (Y and S)

Two different types of permanently lubricated bearings
are used in GT-3 fans:
Y = groove ball bearing, with eccentric securing ring
S = groove ball bearing, with cone sleeve fastening
Self-lubricating bearings have been factory lubricated to
last throughout their entire service life (20,000-40,000
hours of operation). High quality seals in the bearing unit
itself prevent lubricant from seeping out and dripping.
The maintenance of this type of bearing consists of
occasionally cleaning its external surface and performing
inspections to detect any possible abnormal operation or
defective seals. If the latter is detected, the bearings will
have to be replaced. Use the proper tools to prevent
impacts affecting the bearing balls or rollers. Impacts will
cause dents on the bearing rolling races Even the
slightest impact can cause the bearing to emit a
scratchy noise and will lead to a premature wear.

4.7.2 "Y" bearings (YB) needing lubrication

The bearings are factory lubricated and they are
equipped with a grease nipple. As a general rule, the
bearings should be re-lubricated every 6 months; the
amount of grease for re-lubrication is given in Table 4.4.
As these bearings are equipped with high quality seals,
the changing grease is not possible without damaging
the seals. If the bearing is damaged, the whole plummer
block, including the bearing, must be replaced.

4.7.3 Plummer block "SNL" cast iron bearings (H)

Re-lubrication
Plummer block bearings in a fan running 8 hours a day
should be re-lubricated once a year. Plummer block
bearing should be re-lubricated twice a year if the fan is
operated around the clock. New grease is normally
injected while the fan is operating. If the bearing is re-
lubricated, for example, during a maintenance downtime,
the impeller must be rotated in order to distribute the
grease uniformly in the bearing. The amount of grease
required for re-lubrication in grams/greasing time is :
0.005 x bearing outer diameter x bearing width
(measured in mm).
Please note that an excessive amount of grease can
cause a temperature peak in the bearing, which can
damage the lubrication properties of the grease and lead
to bearing damage. Stop filling grease when excess
grease starts to seep out of the bearing.
071 080 090 100
Y - - -
Y YB YB YB
S H H H
112 125 140
- -
-
- - -
H H H
CXRT, GT
11