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HEAVY DUTY COMPOSITE FIBER FANS
INSTALLATION, OPERATION & MAINTENANCE MANUAL
CONTENTS
Introduction .........................................................................1
Shipping and Receiving .....................................................1
Handling .............................................................................. 1
Short Term Storage ...........................................................2
Long Term Storage............................................................ 2
Foundation and Supporting Structures ............................2
Fan Installation ...................................................................3
Bearing Installation .............................................................3
Bearing Maintenance ......................................................... 4
Drive Installation .................................................................4
Drive Maintenance .............................................................. 4
Flexible Coupling Installation ............................................ 4
General Motor Maintenance .............................................. 5
FRP Maintenance ...............................................................5
Wheel and Shaft Maintenance ......................................... 5
Housing Maintenance......................................................... 6
Structural Maintenance ...................................................... 6
Duct Connections ............................................................... 6
Optional Accessories ......................................................... 6
Fan Operation – Safety .....................................................6
Operation Checklist ............................................................7
Troubleshooting Guidelines................................................ 7
Troubleshooting Problems ................................................. 7
Air Capacity Problems ..................................................7
Noise Problems .............................................................7
Vibration Problems ........................................................ 7
Bearing Problems .......................................................... 8
Drive Problems .............................................................. 8
Motor Problems .............................................................8
Limitation of Warranties and Claims ............................. 10
INTRODUCTION
This manual has been prepared to guide the users of
heavy duty composite fiber fans in the proper installation,
operation, and maintenance procedures to insure maximum equipment life with trouble-free operation. These
fans are made from a corrosion resistant reinforced plastic (FRP). It is the responsibility of the purchaser, installer, and user to provide qualified personnel experienced in
the installation, operation, and maintenance of composite
fiber air moving equipment.
Since many fans of this type have custom features or
components, please refer to the attached appendices for
additional information. When manufacturers of components provide detailed installation and operation manuals,
they will be provided. Because of the wide variety of
equipment covered in this manual, the instructions given
here are general in nature.
Additional product and engineering information is available at www.tcf.com.
For safe installation, startup, and operational life of this
equipment, it is important that all involved with the equipment be well versed in proper fan safety practices and
read this manual. Please review the safety section before
beginning any work. It is the user’s responsibility to make
sure that all requirements of good safety practices and
any applicable safety codes are strictly adhered to.
IM-410
August 2014
SHIPPING and RECEIVING
All Twin City Fan & Blower products are carefully
constructed and inspected before shipment to insure the
highest standards of quality and performance. Compare
all components with the Bill of Lading or Packing List
to verify that the proper unit was received. Check each
unit for any damage that may have occurred in transit.
Any damage should be reported immediately to the carrier and the necessary damage report filed.
HANDLING
Handling of all air moving equipment should be conducted by trained personnel and be consistent with safe
handling practices. Verify the lift capacity and operating
condition of handling equipment. Maintain handling
equipment to avoid serious personal injury.
Units shipped completely assembled may be lifted
with slings and spreader bars. (Use well-padded chains,
cables, or nylon straps.) On most units, lifting lugs are
fashioned to protect the fan and fan housing from damage. Never lift a fan by the inlet or discharge flange,
shafting or drives, wheel or impeller, motor or motor
base, or in any other manner that may bend or distort
parts. Never lift with slings or timbers passed through
the fan inlet.
Partial or disassembled units require special handling.
All composite parts should be handled in a fashion
which protects the laminate structure plus its outer gel
coat surface from damage. All composite parts should
be handled such that forces are not concentrated to
avoid bending or distortion. Never allow the outer gel
coat surface to be damaged due to any sudden impact
forces or any stress that may cause the gel coat to be
cracked.
The fan housing should be lifted using straps and
spreaders. Do not distort the fan housing (scroll and side
plates) when lifting.
Bearing pedestals should be lifted using straps or
padded chains. Under no circumstances should an
attached or separated bearing pedestal be lifted by the
shaft, bearings, drives, motor, or impeller.
The single width shaft and wheel sub-assembly may
be lifted using a hoist with a sling around the shaft at
a point nearest the wheel. Take care not to scratch the
shaft where the bearings or drive will be mounted. Never
lift or support the sub-assembly by the wheel. Never lift
the shaft and wheel sub-assembly by the wheel blades,
wheel cone, or the wheel back plate. Always support
the sub-assembly by the shaft when lifting or storing.
©2014 Twin City Fan Companies, Ltd.
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Never transport the shaft and wheel sub-assembly by
rolling the wheel to its desired location, as this will damage the gel coat and can affect the wheel balance. Do
not support the shaft and shaft sub-assembly on the fan
housing sides.
Bent shafting is a source of vibration and bearing
failure, so handle the shaft with care. Any scratches on
the shaft may be removed with a fine grit emery cloth,
crocus cloth, or whetstone.
SHORT TERM STORAGE
If fan installation is to be delayed, store the unit in an
environmentally stable and protected area. During storage,
the fan should not be subjected to vibration or shock
loading from external sources, as bearing damage may
occur. The unit should be reasonably protected from any
impacts. Cover the fan to prevent any foreign material or
moisture from entering the fan inlet or discharge. Protect
the fan bearings, drives, and motor bearings from moisture.
LONG TERM STORAGE
Extended storage requires monthly inspections to be
performed and documented.
Fan bearings tend to take on moisture if the atmosphere they are stored in is not at a constant temperature.
To avoid corrosion, it is necessary to keep the bearings
full of grease and to rotate the fan shaft periodically. Even
when full of grease, bearings will take on moisture, so it
is necessary to purge the bearings with new grease to
expel moisture every thirty days. It is recommended that
when the bearing are being greased, that the fan shaft is
rotated by hand. Do not use high pressure greasers as
they may ruin the bearing seals.
The drive and belt should be removed if the fan is to
be stored for a prolonged period of time. Exposed
machined surfaces on the sheaves, fan shaft, and motor
shaft are to be suitably protected against rust. The drives
should be labeled for service and stored in a dry place.
Belts should be coiled without kinks, placed in a heavy
carton, and stored in a dry, well ventilated place. Storage
conditions should not exceed 85°F (29°C) and 70% humidity to prevent belt deterioration.
If the unit was supplied with a motor, the motor should
be stored in a clean, dry, vibration-free location. The motor
windings resistance should be measured at this time and
recorded for comparison prior to placing into service. The
winding temperature should be kept slightly above that of
the surroundings to prevent condensation from occurring.
This can be accomplished by energizing the motor’s internal heaters, if it is so equipped, or by using space heaters.
If it is impossible to heat the windings, the motor should
be wrapped tightly with a waterproof material which also
encloses several bags of desiccant. Replace the desiccant
regularly to prevent moisture problems. The motor rotor
should also be rotated monthly to assure the bearings are
well covered in grease.
If the fan housing was supplied with a drain connection,
this plug should be removed to prevent any moisture from
accumulating in this portion of the unit during storage.
Fan Storage Procedure – Fans should be stored indoors
whenever possible in an area where control over temperature, moisture, shock, and dust is reasonably maintained.
If units are to be stored outside exposed to the elements,
they should be covered with a water-resistant material.
Stored equipment should be stored on a clean, dry floor
or blocked up off the ground on blocks to prevent unit
from setting in any water. The floor or blocks upon which
the fans rest upon must be stable and capable of providing continuous support to the fan structure which will
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prevent uneven loading of the fan structure. The fan bearings should be shielded individually from water and dirt;
however, do not tightly seal the bearings to avoid trapping
condensation. If shock or vibration will be present during
the storage period, the unit may need to be placed on
some type of vibration dampening material to aid in preventing brinelling of the bearing surfaces.
Periodic Check – On a monthly interval, the equipment
should be checked to ensure that it has remained in an
acceptable stored condition. Make sure there is no corrosion, no damage to the unit, and that there is no debris
within the fan housing.
The fan (and motor, if supplied) should be rotated several times by hand while adding enough grease to replenish the bearing surfaces with fresh grease and to maintain
a full bearing cavity. Grease used must be compatible with
that already supplied in the motor and fan bearings. The
fan impeller should be left at approximately 180° from that
of the previous month to prevent the shaft and impeller
from taking a set in one position.
Consult the motor manufacturer for proper storage,
space heater connection, and lubrication, if applicable.
Storage records should be maintained which indicate the
above requirements have been followed.
Prior to Start-Up – When the unit is removed from storage, all grease in the fan bearings should be purged and
replenished with fresh grease as per the lubrication decal.
Spherical roller bearings split pillow block housings should
be recharged with grease. The bottom half of the housing
should be 1/3 full.
The motor winding resistance should be measured to
verify that it is still at a satisfactory level compared to the
value recorded prior to storage. Motor is to be installed
on the fan per original location. Motor shaft and fan shaft
to be cleaned to bare metal.
Drives are to be cleaned to bare metal, installed, and
aligned per manufacturer’s recommendations.
If belts show signs of deterioration, they should be
replaced prior to start-up. Belts are to be installed and
tensioned per manufacturer’s recommendations.
Replace the fan housing drain plug, if applicable.
FOUNDATION and SUPPORTING
STRUCTURES
The preferred means of floor mounting a fan is on a
well-designed, flat, level concrete foundation. The foundation
should have a mass of at least three to five times that of
the supported assembly. The foundation should extend at
least 6” beyond the outer dimensions of the fan and driver;
however, it should be no more than twice the area required
for the equipment. If it is made larger, the mass should be
increased accordingly to resist rocking modes of vibration.
“J”, “L”, or “T” type anchor bolts of sufficient size should
be used and should be tied into the foundation reinforcing
bar. After the concrete is poured, a pipe sleeve with a
diameter of 2 to 2-1/2 times the anchor bolt diameter
should be provided around each anchor bolt to facilitate
final adjustment (see Figure 8). The mounting surface of the
foundation should be smooth for good shim contact. When
deciding the thickness of the foundation, approximately 1"
to 1-1/2" in height should be allowed for shimming, grouting,
and leveling nuts.
If a structural steel base or platform is to be used for
fan mounting, the support structure must be designed for
the weight of the fan, the live loads imposed by rotation of
the rotor and driver, and any external live loads. The structure should be designed to ensure that no natural frequency will be present within 30% of the fan speed and
Twin City IM-410
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motor speed. This is especial true if the structure supports
more than one fan.
Fan inlet and outlet ducting should have independent
support. Do not use the fan to support ducting as the fan
housing or pedestal may become distorted or cracked. Flex
connectors at the fan inlet and discharge will isolate the
duct loads from the fan plus eliminate transmission of vibration. Use stainless steel fasteners with large washers under
the head and nut to increase the load bearing area. Do not
tighten the fasteners to the point of crushing the flange.
FAN INSTALLATION
Follow proper handling instructions as given earlier.
1. Move the fan to the final mounting position.
2. Remove skid, crates, and packing materials carefully.
3. If vibration isolation is to be used, place isolation base
on mounting bolts. Line up holes in fan base with
bolts.
4. Place the fan on mounting structure. Carefully level
the unit (checking the level on the fan shaft) on the
foundation and shim as necessary using stainless
steel shims on both sides of each anchor bolt. Be
careful not to force the fan to the mounting structure/
foundation. This may cause the bearings to become
misaligned or pinched, which can cause vibration and
premature failure.
5. Check the alignment of the bearings. Shim or reposition the bearings if necessary.
6. Check face alignment of sheaves on belt driven units
(reference Figure 4). Check tension of belts to see if
it is sufficient. Sheaves on belt driven fans are often
provided with taperlock bushings. When tightening
bushing bolts, proceed in a progressive manner to
avoid cocking the tapered surfaces between the bushing and the sheave.
7. Check alignment of factory mounted couplings, as
they are subject to misalignment during shipping and
installation. Realign to within 0.002" offset and parallel. Allow for thermal growth of the motor by setting
the motor 0.001" low for each inch of shaft up to
0.005". NOTE: Grid-type and gear-type couplings
require lubrication.
8. Check the tightness of the foundation bolts, motor
bolts, sheaves, and bearings. Make sure there is no
rubbing or binding and that the wheel-inlet cone
clearances are correct.
9. Check that bearings are fully lubricated. For spherical
roller bearings with split pillow block housings, the
bottom half of the housing should be 1/3 full of
grease. For oil lube bearings, the oil level should
submerge the bottom-most roller halfway.
10. Install any accessories that were shipped loose from
the factory.
11. Grouting is the final installation step. Check all stainless steel shims before grouting to make sure the fan
is resting evenly on all points with anchor bolts
secured to hold the shims. Use shims with sufficient
space allowed for working the grout. The concrete
foundation should be clean and well moistened before
pouring grout. Use a commercial grade non-shrinking
grout and be especially sure when pouring grout that
the anchor bolt sleeves are filled. Refer to Figure 8
for a detail of a proper foundation, grout allowance,
and anchor bolt sleeve.
expansion and expansion bearings. The position of these
bearings cannot be interchanged.
Spherical Roller Bearings with Split Pillow Block
Housing
1. The bearings should be disassembled, taking care not
to interchange parts between bearings. Parts of one
bearing are generally not interchangeable with parts
from another bearing.
2. The lower bearing housing should be bolted loosely
to the pedestal and seals, bearing, and adapter sleeve
assembly should be placed loosely on the shaft.
3. The rotor assembly with the seals and bearings
should next be positioned over the housing and carefully placed into the lower housing.
4. The thrust locking ring should be installed in the bearing closest to the drive sheave or coupling unless
otherwise noted in the drawing.
5. When installing adapter sleeves, tighten for reduction
in clearance per manufacturer’s instructions.
6. Bend down a tab on the lockwasher after finishing
adjustment.
7. Grease or oil according to manufacturer’s instructions.
8. Install the bearing housing cap and cap bolts. Tighten
bearing housing cap bolts and bearing mounting
bolts. Torque to bearing manufacturer’s instructions.
Solid Pillow Block
1. Slide shaft in bearing bore to proper location. Note:
Shaft should slide easily if self-aligning feature of the
shaft is within its limits. Sling the rotor assembly into
place and loosely bolt the bearings in place.
2. When bearings are in place, torque the base bolts
using values from Table 1, and tighten the collar
setscrews to manufacturer’s specification.
3. Grease the bearings per manufacturer’s instructions.
Figure 1.
SUPPORT STAND
(HOUSING FRAME)
MOTOR
SHAFT
PEDESTAL
WHEEL / IMPELLER
HOUSING
BEARINGS
INLET FUNNEL
Figure 2. Wheel Placement
Size
165 182 200 222 245 270 300 330
A
16.50 18.25 20.00 22.25 24.50 27.00 30.00 33.00
B
0.44 0.56 0.63 0.69 0.75 0.88 0.97 1.06
Size
365 402 445 490 542 600
A
36.50 40.25 44.50 49.00 54.25 60.00
B
0.94 1.03 1.13 1.25 1.38 1.56
BCSF Wheel Placement
BEARING INSTALLATION
The following section gives some general instructions
on bearing installation. When bearings are field installed,
the specific installation manual for the bearings should be
followed carefully. Always make sure to check the fan
assembly drawing or instructions for location of the non-
Twin City IM-410
A
DIA
B
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BEARING MAINTENANCE
Proper lubrication of the fan bearings helps assure
maximum bearing life. All fans are equipped with decals
indicating relubrication intervals for normal operating conditions. Figures 9, 10 and 11 illustrate the lubrication schedules for ball bearings, solid pillow block spherical roller
bearings, and split pillow block spherical roller bearings,
respectively. Note that all speeds shown do not apply to
all shaft sizes in that group. Consult the factory if in doubt
of maximum speed for a particular bearing. Note that every
installation is different and the frequency of relubrication
should be adjusted accordingly.
On applications where there is high moisture or heavy
dust, the lubrication frequency may need to be doubled or
tripled to adequately protect the bearings.
Observation of the conditions of the grease expelled from
unit ball or roller bearings at the time of relubrication is
the best guide as to whether regreasing interval and
amount of grease added should be altered.
Spherical roller bearings with split pillow block housings
should be lubricated until grease purges or overheating
may result. Follow the lubrication interval and amount
noted in Figure 11. Spherical roller bearings with split pillow block housings should be serviced once per year.
Remove cap, clean out old grease, and replace by filling
the bottom half of the housing 1/3 full.
Greases are made with different bases. There are synthetic base greases, lithium base, sodium base, poly urea
base, etc. Avoid mixing greases with different bases. They
could be incompatible and result in rapid deterioration or
breakdown of the grease. The lubrication sticker identifies
a list of acceptable lubricants. All bearings are filled with
a lithium based grease before leaving the factory. When
the fans are started, the bearings may discharge excess
grease through the seals for a short period of time. Do
not replace the initial discharge because leakage will cease
when the excess grease has worked out. Sometimes the
bearings have a tendency to run hotter during this period.
This is no reason alarm unless it lasts over 48 hours or
gets very hot (over 200°F). When relubricating, use a sufficient amount of grease to purge the seals. Rotate bearings by hand during relubrication.
DRIVE INSTALLATION
Mount drives as follows:
1. Slip (do not pound) proper sheave and its bushing
onto corresponding shaft (position per Figure 3).
CAUTION: placing fan sheave on motor can over
speed the wheel and cause structural failure.
2. Align sheaves with a straightedge extended along
sheave face, just making contact in two places on
outside perimeters of both sheaves (reference Figure
Figure 3.
Sheave Position
KEYWAY LENGTH
SHEAVE LINED
UP WITH END
OF KEYWAY
RUN OUT
RUN OUT OF
KEYWAY
Figure 4.
Sheave Alignment
4). This “four-point” alignment may also be checked
with a string tied to the shaft behind one of the
sheaves. The string is then pulled taut over the faces
of the sheaves to check the alignment at the four
points at the outside perimeters. Each sheave should
be rotated about one-half revolution during the check
to look for excessive runout or a bent shaft.
3. Install and tighten the belts. Run the drive for a few
minutes to seat the belts. When tightening the belts,
slide the motor in to slip the belts on. Do not use
a pry bar, as this may damage the belt cords.
Tighten the belts to the proper tension. Ideal tension
is just enough tension so that the belts do not slip
under peak load. Many drives are provided with tensioning data which identifies the load to apply at the
center of the span and the allowable deflection from
this force. This may be checked visually (look for a
slight bow on slack side), or listen for a squeal on
startup, indicating that the belts are too loose.
Recheck sheave alignment.
4. After initial installation of belts, recheck belt tension
again after a few days and adjust tension as needed.
(New belts require a break-in period of operation.)
DRIVE MAINTENANCE
V-belt drives need periodic inspection, re-tensioning,
and occasional belt replacement. Look for dirt buildup,
burrs, or obstructions when inspecting drives. These can
cause premature belt or drive replacement. If burrs are
found, use fine emery cloth or a stone to remove the
burr. Be careful that dust does not enter the bearings.
Check the sheaves for wear. Excessive slippage of
belts on the sheaves can cause wear and vibration.
Replace worn sheaves with new ones. Carefully align
sheaves to avoid premature sheave failure.
Observe belts for signs of wear. If fraying or other
wear is observed to be mostly on one side of the belts,
the drives may be misaligned. Reinstall the drives according to instructions given for “Drive Installation”. Never use
belt dressing on any belts. Make sure the sheaves and
belts are free from all forms of lubricants.
Always replace the entire set of v-belts and never mix
used belts with new belts. Follow instructions given for
“Drive Installation”.
FLEXIBLE COUPLING INSTALLATION
These instructions are general for the installation of
several types of flexible couplings and should not be used
as a substitute for more specific manufacturer’s instructions. The coupling manufacturer’s installation data is available and will give specific dimensions for alignment limits,
lubricants, etc. Refer to Item 7 in “Fan Installation” section
for alignment requirements.
Before preparing to mount the coupling, make sure that
all bearings, shaft seal, or other shaft mounted components
have been installed on the shaft.
When mounting and keying the interference fit coupling
halves to the shaft, follow supplied instructions for heating
and shrink fitting. Set the coupling halves for the normal
gap specified by the manufacturer. Coupling gap is illustrated in Figure 5.
The two types of misalignment are illustrated in Figure
5. Typically angular alignment is checked with feeler gages
between the hub faces. When angular alignment has been
adjusted to within manufacturer’s specification by shimming, if necessary, then parallel alignment can be checked
with a straightedge and feeler gages on the hub halves’
O.D. When shimming has brought parallel alignment within
specification, angular alignment and gap should again be
checked, and adjustments made if necessary. A dial indica-
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Twin City IM-410
Page 5
Figure 5. Coupling Installation
Y
X
P
P
FF
GAP
ANGULAR PARALLEL GAP AND
MISALIGNMENT MISALIGNMENT END FLOAT
X-Y = ANGULAR MISALIGNMENT
P = PARALLEL OFFSET (MISALIGNMENT)
F = END FLOAT
tor or laser alignment method may be used to more
accurately take the measurements described above.
Special adjustments may need to be made for couplings
used with some equipment. As an example, when couplings are used with motors which have sleeve bearings,
the coupling may require provisions for limiting end float.
Larger drives may grow vertically in operation (due to
thermal expansion) requiring the driver side to be set
slightly low when at ambient temperature. Refer to specific instruction manuals or assembly drawings.
Thoroughly clean the coupling halves after completion
of alignment. Reassemble the coupling and tighten cover
bolts, washers, and nuts. Lubricate per manufacturer’s
recommendations.
GENERAL MOTOR MAINTENANCE
The three basic rules of motor maintenance are keep
the motor clean, keep the motor dry, and keep the motor
properly lubricated.
Keeping the motor and its windings clean is important
because dirt and dust serve as thermal insulation. Heat
normally dissipated by the motor is trapped causing overheating and/or premature failure. Blow dust and dirt out of
windings and off the motor periodically. Use a clean and
dry low pressure (50 psig) airstream so that winding damage does not occur. Keep the area surrounding the motor
open so that air can circulate through the motor cooling
fan.
Motors should be kept dry to avoid electrical short
circuits. Motors kept in storage for long periods of time can
have moisture condense on the windings. Be certain the
motor windings are dry before energizing the motor.
Lubrication requirements are normally attached to the
motor. Do not overlubricate. Motor lubricants are often not
the same as the fan bearing lubricant. Some smaller motors
are lubricated for life. Motor bearing lubrication, if required,
must follow a rigorous schedule. Motors less than 10 hp
running about eight hours a day in a clean environment
should be lubricated once every five years; motors 15 to
50 hp, every three years; and motors 60 to 150 hp,
yearly. For motors in a dusty or dirty environment or running 24 hours a day, divide the service interval by two. If
the environment is very dirty or has a high ambient temperature, then divide the service interval by four.
Motors controlled by variable frequency drives (VFD)
should be wired in accordance with the VFD manufacturer’s
instructions. The motor must be grounded to earth and
proper shielded cabling must be used. Motor shaft grounding rings should be considered to minimize shaft voltage
from arcing through the motor bearings.
FRP MAINTENANCE
Corrosion Resistance – The type of reinforcement fiber
used in making the laminate structure will influence its
weight, strength, and also the wheel maximum safe speed.
The resin selected will influence the corrosion resistance of
the laminate and hence the product durability. The Twin
City Fan & Blower standard resin used for manufacturing
Twin City IM-410
wheel components is the epoxy vinyl ester product
Derakane 510A40 from Ashland. The TCF standard resin
used for manufacturing housing components is the polyester product Hetron 92FR from Ashland with the option of
using Derakane 510A40. Both products (without addition of
antimony trioxide) have a flame spread rating less than 25
as tunnel tested per ASTM E84.
See the “Corrosive Atmosphere Guide” that is located
within TCF Catalog 410 for suggested resin to use in
various corrosive environments. Final selection of the resin
should always be based upon customer’s experience and/
or testing conducted with desired fume concentration and
temperature. Additional corrosion resistance information is
available from Ashland at ashland.com.
Perform periodic visual inspection of the FRP laminate
to determine there is no adverse deterioration occurring
which will compromise the product’s structural integrity.
Periodic cleaning can prolong product life and should be
investigated.
Abrasion Resistance – Fans constructed of FRP materials
are intended for clean air service with humidity less than
100% or for air laden with corrosive fumes. FRP laminate
is inherently “softer” than carbon steel and stainless steel.
FRP products should not be used to convey air which
contains particulate or water (liquid or fog). Severe erosion
can occur if these items are present in the airstream. The
resin rich outer surface is subject to wear and if this layer
is compromised, the corrosive fumes can then attack the
reinforcement fiber. The combination of corrosion and abrasion can quickly lead to product failure.
Perform periodic visual inspection of the FRP laminate
to determine there is no adverse deterioration occurring
which will compromise the product’s structural integrity.
Weather Resistance – FRP products installed outdoor without adequate protection are subject to damage from local
weather conditions. This can include impact damage resulting from hail or windblown objects, surface chalking or
discoloration from ultraviolet light exposure, and reduced
strength due to temperature effects resulting from high
ambient temperature and solar radiation combined with high
internal air temperature.
WHEEL and SHAFT MAINTENANCE
Periodically inspect the fan shaft and FRP wheel for
buildup, corrosion, and signs of excess stress or fatigue.
Dust or chemical deposits will usually build up on
the wheel evenly and they present no problem to performance or operation until they become thick enough
to break away in crust-like pieces. When this happens,
the wheel may be thrown out of balance and the resulting vibration could be serious. When removing this
crustaceous accumulations, care should be taken not to
clean the fan wheel with sharp objects which might
damage the laminated surface and reduce its corrosion
resistance. Replace the wheel and shaft sub-assembly if
it shows signs of excessive wear or damage to the
laminate.
The fan wheel and shaft sub-assembly is factory balanced and then the entire fan assembly is test run to
assure vibration levels are within tolerance. It is not
uncommon for the fan wheel to require some trim balancing after installation or after some period of time in
operation. Addition of FRP weights to the backplate or
frontplate can be made to bring the vibration levels back
within specification.
Check the interface between the shaft sleeve and the
wheel backplate. This joint is critical to prevent infiltration of corrosive fluids to the shaft and hub. Replace
the sub-assembly if needed.
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Check the condition of the shaft to verify it has not
RIGHT
WRONG
suffered any corrosive attack. Replace the sub-assembly
if needed.
HOUSING MAINTENANCE
The fan housing is assembled from two FRP halves that
are bolted together with stainless steel bolts and the interior joint is secondary bonded to prevent leakage. Check
the interior surfaces for any evidence of FRP damage and
repair, if possible, or replace if necessary. An optional
Inspection Door and Drain is available.
The inspection door is bolted to the housing with stainless
steel bolts and sealed with a corrosion resistant gasket.
The FRP drain is secondarily bonded to the low point
in the housing to minimize accumulations of liquid. Check
to insure the drain is not clogged and any fluid is discharged appropriately.
STRUCTURAL MAINTENANCE
All structural components or devices used to support or
attach the fan to a structure should be checked at regular
intervals. Vibration isolators, bolts, foundation, etc. are all
subject to failure from corrosion, erosion, and other causes.
Improper mounting can lead to poor operation characteristics or fan fatigue and failure. Check metallic components
for corrosion, cracks, or other signs of stress. Concrete
should be checked to insure the structural integrity of the
foundation.
DUCT CONNECTIONS
The fan support structure is normally not designed to
carry static loads imposed by the weight of ducts, silencers,
stacks, etc. or dynamic loads from wind or seismic events.
Supporting these loads on the fan inlet and discharge can
cause housing distortion and may cause performance problems due to the relation of fan housing to wheel. Excessive
loads on the fan housing may damage the FRP housing
and render it unfit for service.
Since FRP is used primarily for its corrosion resistance,
it is recommended that stainless steel fasteners be used.
Use a large washer under the head of the bolt and nut to
increase the load bearing area in contact with the FRP. Do
not tighten these fasteners to the point of crushing the FRP
laminate.
Use of flexible connections is recommended for all
installations and especially when the fan is mounted on
vibration isolators.
OPTIONAL ACCESSORIES
1. Shaft Seals – The standard shaft seal is a Teflon
membrane style shaft closure seal that minimizes
leakage around a FRP sleeve that is encapsulated
over a carbon steel shaft. Optional shaft seal is
either a Viton or Teflon lip seal that is installed in
a cast FRP seal housing. The shaft is encased with
a stainless steel shaft sleeve over a steel shaft. Care
must be taken to insure the integrity of the joint
between the shaft sleeve and the wheel backplate.
Other configurations of shaft seals are available for
special applications.
2. Bolt-On Variable Inlet Vanes – Variable inlet vanes
made of FRP are provided as assemblies externally
to the fan in flanged cylinders that are bolted to the
fan inlet. The vanes are used to control volume and
save power in installations where different volumetric
operating conditions are used. Variable inlet vanes
may be provided for operation with powered operators or for manual operation. Powered operator
instructions and operating manuals will be provided
when included.
6
3. Inlet Box and Inlet Box Dampers – FRP inlet boxes
may be provided to allow transition from a rectangular duct to the fan inlet. FRP inlet box dampers
may also be provided for volumetric regulation
similar to inlet vanes. FRP inlet dampers are usually provided as a complete assembly and are
installed with the damper axis parallel to the fan
shaft. They must be installed to pre-spin the air in
the direction of fan rotation. See Figure 6 below.
Damage may occur if the fan is operated regularly
with dampers less than 30% open.
4. Outlet Dampers – FRP outlet dampers are usually
provided completely assembled like the inlet dampers. The damper is bolted to the fan discharge
flange for volume control.
Figure 6. Orientation of Damper Blades
5. Oil Circulating System – Usually the following modifications will have to be made to the split pillow
block bearings if an oil circulating system is used.
a. Four drain holes will be drilled in the bearing,
two on each side of the bearing. Because of
this, the bearing may be drained from either
side. (Drain from both holes on one side of the
bearing.)
b. The bearing will be packed with grease to pre-
vent corrosion until installed and started up.
The drain holes will be plugged with plastic
coversto make sure they are open. NOTE: The
customer MUST REMOVE most of the grease
using solvent and remove the plastic covers
prior to starting the oil circulating system.
c. A wet sump will be added in case of circulat-
ing oil pump failure. Seals will be provided to
minimize oil leakage due to oil splashing.
d. The grease zerk on top of the bearing will be
removed for that hole to be used as the oil
inlet.
6. Anti-Rotation Clutch – Damage will occur if the fan
is operated in the wrong rotation. Run the motor
uncoupled from the fan to establish the proper rotation.
FAN OPERATION - SAFETY
For general safety practices relating to air moving
equipment, see AMCA Publication 410.
Twin City Fan & Blower has many safety accessories
available. These safety devices include (but are not limited to) belt guards, shaft guards, inlet guards, and
discharge screens. The use, abuse, or non-use of
safety devices is the responsibility of the purchaser.
Facility-related safety conditions include fan accessibility and location.
• How easily can non-service personnel access
the unit?
• Is the fan in a hazardous duty environment?
• Was the unit ordered for this duty?
Other concerns must also be addressed.
All fans should be powered through safety switches
which are easily accessible to service personnel and in
close proximity to the fan. Every safety switch should
Twin City IM-410
Page 7
have the capability to be “Locked Out – Tagged Out”
by the service person working on the unit. The key to
the lock is to be retained by the service person to prevent the accidental powering up of the fan while the
service person is working on the fan.
Appropriate hearing protection is to be used by all
personnel in the area of the fan while it is in operation.
Due to the nature of applications where FRP fans may
be used, it is highly probable that the airstream constituents should not come in contact with body parts of
the service person or their clothing. Follow all local plant
safety requirements in regards to the exposure for the
specific airstream constituents present.
Fan housings equipped with optional access doors
should never be opened while the fan is in operation.
The close proximity of the fan wheel to the access door
opening is very dangerous when operating and can
present a fatal consequence.
Fans by their nature develop a negative pressure
(suction) at their inlet while in operation. Great care must
be taken to prevent this force from causing anything that
is near the inlet to be sucked into the rotating fan wheel.
Great harm to the fan as well as to the object taken
inside the fan can occur. This can also present a fatal
consequence. The same affect can be had due to the
high velocity air stream present which will also force
objects into the fan.
Even when the fan is not in operation, sometime
there are pressure differences present which can cause
the fan wheel to “windmill”. Great care must be exercised to prevent injury when working on the fan. It is
advisable to temporarily block the wheel to prevent
unexpected rotation and potential injury from occurring.
OPERATION CHECKLIST
□ Verify that proper safety precautions have been followed.
□ Electrical power must be locked off.
□ Fan Assembly is properly grounded for static dissipation
option.
Check Fan Mechanism Components:
□ Nuts, bolts, and setscrews are tight.
□ Mounting connections are properly made and tightened.
□ Bearings are properly lubricated.
□ Wheel, drives, and fan surfaces are clean and tightened.
□ Rotating assembly turns freely and does not rub.
□ Check for fan/wheel overlap per Figure 2.
□ Drives mounted on correct shaft, properly aligned,
and properly tensioned.
Check Fan Electrical Components:
□ Motor is wired for proper supply voltage.
□ Motor was properly sized for power required by the
rotating assembly.
□ Motor is properly grounded.
□ All leads are properly insulated.
Trial “Bump”:
□ Turn on power just long enough to start assembly
rotating.
□ Check rotation for agreement with rotation arrow
□ Listen for any unusual sounds.
Run Unit Up To Speed:
□ Bearing temperatures are acceptable (<200°F) after
one to two hours of operation.
□ Check for excessive levels of vibration. Filter in readings
should be 0.15 in/sec (peak) or less.
After One Week Of Operation:
□ Check all nuts, bolts, and setscrews and tighten if
necessary.
□ Readjust drive tension if necessary.
TROUBLESHOOTING GUIDELINES
Use current safety practices when investigating fan or
system performance problems. General safe practices
and performance troubleshooting guidelines can be
found in AMCA Publications 410 and 202, respectively.
Fan application and field measurement procedures can
be found in AMCA Publications 201 and 203.
Below is a list of possible areas to check when air,
sound, or operational values do not match expectations.
Most fan problems can be pinpointed to one of these
common causes.
TROUBLESHOOTING PROBLEMS
Air Capacity Problems
1. Resistance of the system is not at design rating. If
resistance is lower than expected, both airflow and
horsepower may be up. If resistance is higher than
anticipated, air volume will be down.
2. Fan speed is not at design speed.
3. Air density at the fan inlet is not at the design value.
Also check air performance measurement techniques
and procedures.
4. Devices for air modulation are closed or plugged.
Also check filters.
5. Wheel mounted improperly or is rotating in reverse.
6. Parts of the system or fan have been damaged or
need cleaning.
Noise Problems
1. Air performance is incorrect and the fan is not at the
design point of operation. Fan is being forced to
operate in an unstable flow region.
2. Bearing failure. Check bearing lubrication, alignment,
and fastener tightness.
3. Supply voltage high or inconsistent supply frequency.
Adjustable frequency controllers (VFD) can generate
motor noise.
4. Objects which are installed in a high velocity air stream
can generate noise. This includes flow sensors, turning
vanes, etc.
5. Poor fan inlet conditions.
6. Acoustic or sound measurement procedure is incorrect.
Vibration Problems
1. Misalignment of drive components. Check belts or
coupling.
2. Poor foundation or mounting structure (resonance).
3. Foreign material attached to the rotating components.
4. Damaged rotating components (bearings, shaft, fan
wheel, sheaves, coupling, seals, etc.)
5. Broken, loose, or missing setscrews, bolts, or fasteners.
6. Vibration transmitted by another source.
7. Fan is operating in stall or unstable flow region.
Figure 7. Vibration Guidelines
Seismic Vibration Velocity Limits for Operation In-Situ
Condition
Start-up
Alarm
Shutdown
Value shown are peak velocity, mm/s (inches/s), Filter out.
Table taken from ANSI/AMCA Standard 204-05, Table 6.3.
AMCA defines BV-3 for applications up to 400 HP; BV-4 for applications over 400 HP.
Fan
Application
Category
BV-3 6.4 (0.25) 8.8 (0.35)
BV-4 4.1 (0.16) 6.4 (0.25)
BV-3 10.2 (0.40) 16.5 (0.65)
BV-4 6.4 (0.25) 10.2 (0.40)
BV-3 12.7 (0.50) 17.8 (0.70)
BV-4 10.2 (0.40) 15.2 (0.60)
Rigidly Mounted
mm/s (in./s)
Flexibly Mounted
mm/s (in./s)
Twin City IM-410
7
Page 8
Bearing Problems
Generally speaking, Twin City Fan & Blower uses three
types of bearings:
1. Ball bearings with setscrew lock;
2. Spherical roller bearing with setscrew lock;
3. Spherical roller bearing with adapter sleeve/taper lock
feature to attach them to the shaft.
Ball Bearings with setscrew lock - These are self-aligning
bearings and should present no alignment problems with
one exception: i.e., on Sealmaster bearings, there is a pin
beneath the grease fitting which prevents the bearing outer
race from rotating. Should this pin jam, the bearing loses
its alignment feature.
Common failure causes are (a) setscrews loosening and
shaft turning within the bearing inner race, and (b) crowned
bearing supports. Loosen one bolt and measure the clearance between the bearing foot and the support. Add shims
to compensate.
Spherical Roller Bearings with setscrew lock - The selfaligning characteristic of these bearings are inherent in the
spherical roller design. The closer that these bearings are
to perfect alignment, the cooler they will operate.
Common failure causes are the same as with the ball
bearings, mainly setscrews loosening and crowned bearing
supports.
Spherical Roller Bearings with adapter lock - Again, the selfaligning feature is inherent in the spherical design. Good
alignment results in a cooler operating bearing. The faster
the bearing operates the more critical this becomes.
A common cause of failure is improper installation
practice. Removing too much radial internal clearance from
the bearing can cause preloading of the bearing with the
result of premature failure; and removing not enough internal clearance can allow the shaft to rotate within the
adapter sleeve with the result of noise, heat, and failure.
Properly tightened, this method of attaching a bearing to
a shaft is second only to an interference fit. Crowned
bearing supports can also preload these bearings and
should be checked by loosening one bolt and checking
the clearance between the bearing foot and the support.
Add shims to compensate.
Lubrication - The major cause of bearing failure is contamination of grease, insufficient grease, or incompatibility
of grease. If a fan is to be stored for any length of time
at the job site, the bearings immediately should be filled
with grease while rotating the shaft and then the bearings
should be regreased and shaft rotated monthly. This will
prevent moisture, which condenses within the bearing, from
corroding the raceways. Most of the grease used on fan
pillow block bearings are lithium base. Use the greases
shown on the bearing decal. Do not mix greases with different type of bases, but always purge out the initial grease
having one base with the new grease having a different
base.
Initially, follow the lubrication instruction on the side of
the fan. The frequency of lubrication should be adjusted
depending on the condition of the old grease being
purged. This is the responsibility of the user. If the grease
is dirty, the lubrication frequency should be more often.
Bearing Noise – If a bearing is increasing in noise intensity and/or vibration, it will probably result in failure.
Bearing Temperature – If a bearing temperature begins to
gradually rise, it will generally result in failure. A bearing
can operate up to 200°F and perform satisfactorily as long
as the temperature remains constant and the bearing
receives adequate lubrication. Remember that a roller bearing under the same load and speed will be somewhat
noisier and run warmer than a ball bearing. This is normal.
Rough handling and /or dropping a fan can result in
brinelling the bearing. This appears as a clicking noise at
first, and then gradually worsens until failure occurs.
When replacing a bearing, always align the bearings first,
then bolt the pillow blocks to their support, rotate the
shaft, fasten the bearing to it. If the bearing is fastened to
the shaft first, tightening the pillow block blocks may bind
the shaft and preload the bearings.
Drive Problems
1. Belts improperly tensioned.
2. Drive alignment is poor. Check belts or coupling.
3. Coupling lubrication.
Motor Problems
1. Incorrect wiring.
2. Speed of fan is too high.
3. Parts improperly installed or binding.
4. Bearings improperly lubricated.
5. WR2 capability of motor is too low for application.
6. VFD compatible.
7. Cable and grounding correct.
Table 1. Tightening Torques (in lb-ft)
SIZE
#10 — — — — 6
1
⁄4-20 5.5 8 12 7.9 9
5
⁄16-18 11 17 25 16 15
3
⁄8-16 22 30 45 29 30
7
⁄16-14 30 50 70 — —
1
⁄2-13 55 75 110 70 60
9
⁄16-12 — — — — 75
5
⁄8-11 100 150 200 140 135
3
⁄4-10 170 270 380 250 225
7
⁄8-9 165 430 600 — 300
1-8 250 645 900 600 450
1
⁄4-7 500 1120 1500 — —
1
GRADE 2 GRADE 5 GRADE 8 SPLIT QD
8
FASTENER TAPER BUSHINGS (DRIVE)
+
Tolerance: /
For wheel setscrews use Grade 2 values.
The torque values are for nonlubricated
fasteners and Browning Bushings.
For bearing setscrews, use manufacturer’s
recommendations.
If other bushings are used, utilize bushing
manufacturer's specifications.
5%
-
Twin City IM-410
Page 9
Figure 8. Typical Foundation Section
Temporary Form For
Grout Pouring
Hex Nut, Split Ring
Tapered or Flat Wa sher
1" to 1.5"
Grout Allowance
To Be Filled With
Nonshrinking
Machinery Grout
Pipe-Bolt Sleeve
1
/2 Times
Dia. 2 to 2
Bolt Dia. For Correction
of Alignment Errors
Care Should Be Taken
That Anchor Bolt Sleeves
Are Filled With Grout
Lock Washer, and
Leveling Nut, If Used, Should Be
Backed Off After Shimming For
Final Tightening of Hex Nuts
Fan Base Angle
or Structural Steel
Full Width Stainless
Steel Shims
Shimming Surface To Be
Smooth, Level, Dressed
If Necessary
J-Bolt Leg Should Be
Fastened To Foundation
Rebar
Figure 9. Safety & Lubrication Instructions for Fans with Ball
Bearings
WARNING
1. This equipment must not be operated without proper guarding of
all moving parts. While performing maintenance be sure remote
power switches are locked off. See installation manual for recommended safety practices.
2. Before starting: Check all setscrews for tightness and rotate wheel
by hand to make sure it has not moved in transit.
Relubrication Schedule (Months)*
Ball Bearing Pillow Blocks
Speed (RPM)
Shaft DIA
500 1000 1500 2000 2500 3000 3500 4000 4500
1
⁄2" thru 111⁄16"
(13 – 45)
15
1
⁄16" thru 27⁄16"
(50 – 60)
11
2
⁄16" thru 215⁄16"
(65 – 75)
7
3
⁄16" thru 315⁄16"
(80 – 100)
* Suggested lubrication interval under ideal continuous operating conditions. Relubricate while running, if safety permits, until some purging
occurs at seals. Adjust lubrication frequency depending on conditions
of purged grease. Use one-half of listed interval for vertical shaft applications or for 24 hour operation. Hours of operation, temperature, and
surrounding conditions will affect the relubrication frequency required.
1. Lubricate with a high quality NLGI No. 2 lithium-base grease having rust inhibitors and antioxidant additives, and a minimum oil
viscosity of 500 SUS at 100°F (38°C). Some greases having these
properties are:
Shell - Gadus S2 V100 2 Exxon - Ronex MP
Mobil - Mobilith SHC100 Mobil - Mobilith SHC220
2. Lubricate bearings prior to extended shutdown or storage and
rotate shaft monthly to aid corrosion protection.
6 6 5 3 3 2 2 2 1
6 5 4 2 2 1 1 1 1
5 4 3 2 1 1 1
4 3 2 1 1
Figure 10. Safety & Lubrication Instructions for Fans
with Unit Roller Bearings
WARNING
1. This equipment must not be operated without proper guarding of
all moving parts. While performing maintenance be sure remote
power switches are locked off. See installation manual for recommended safety practices.
2. Before starting: Check all setscrews for tightness and rotate wheel
by hand to make sure it has not moved in transit.
Relubrication Schedule (Months)*
Spherical Roller Bearing - Solid Pillow Blocks
Speed (RPM)
Shaft DIA
1" thru 1
(25 – 35)
1
(40 – 55)
2
(60 – 85)
3
(90 – 125)
*Suggested lubrication interval under ideal continuous operating conditions. Relubricate while running, if safety permits, until some purging
occurs at seals. Adjust lubrication frequency depending on conditions
of purged grease. Use one-half of listed interval for vertical shaft applications or for 24 hour operation. Hours of operation, temperature, and
surrounding conditions will affect the relubrication frequency required.
1. Lubricate with a high quality NLGI No. 2 lithium-base grease hav-
Shell - Gadus S2 V100 2 Exxon - Ronex MP
2. Lubricate bearings prior to extended shutdown or storage and
500 1000 1500 2000 2500 3000 3500 4000 4500
7
⁄16"
11
⁄16" thru 23⁄16"
7
⁄16" thru 37⁄16"
15
⁄16" thru 415⁄16"
6 4 4 2 1 1 1 1
4 2 1
3 1
1
2
⁄2 1 1⁄2 1⁄4
1
⁄2 1 1⁄2 1⁄2 1⁄2 1⁄2 1⁄2
1
⁄2 1 1⁄2 1⁄2 1⁄4 1⁄4
1
ing rust inhibitors and antioxidant additives, and a minimum oil
viscosity of 500 SUS at 100°F (38°C). Some greases having these
properties are:
Mobil - Mobilith SHC100 Mobil - Mobilith SHC220
rotate shaft monthly to aid corrosion protection.
⁄2
Twin City IM-410
9
Page 10
Figure 11. Safety & Lubrication Instructions for Fans
with Spherical Roller Bearings with Split Pillow
Block Housings
WARNING
1. This equipment must not be operated without proper guarding of
all moving parts. While performing maintenance be sure remote
power switches are locked off. See installation manual for recommended safety practices.
2. Before starting: Check all setscrews for tightness, and rotate wheel
by hand to make sure it has not moved in transit.
Relubrication Schedule (Months)*
Spherical Roller Bearing - Split Pillow Blocks
Speed (RPM)
Shaft DIA
17⁄16" thru 115⁄16"
(35 – 50)
3
2
⁄16" thru 213⁄16"
(55 – 70)
15
2
⁄16" thru 315⁄16"
(75 – 100)
7
4
⁄16" thru 415⁄16"
(110 – 135)
7
5
⁄16" thru 615⁄16"
(140 – 180)
*Suggested lubrication interval under ideal continuous operating conditions. Remove bearing cap and observe condition of used grease after
lubricating. Adjust lubrication frequency as needed. Use one-half of
listed interval for vertical shaft applications or for 24 hour operation.
Hours of operation, temperature, and surrounding conditions will affect
the relubrication frequency required. Clean and repack bearings annually. Remove old grease, pack bearing full and fill housing reservoir
on both sides of bearings to bottom of shaft.
1. Lubricate with a high quality NLGI No. 2 lithium-base grease having rust inhibitors and antioxidant additives, and a minimum oil
viscosity of 500 SUS at 100°F (38°C). Some greases having these
properties are:
Shell - Gadus S2 V100 2 Exxon - Ronex MP
Mobil - Mobilith SHC100 Mobil - Mobilith SHC220
2. Lubricate bearings prior to extended shutdown or storage and
rotate shaft monthly to aid corrosion protection.
3. Purge or remove old grease when changing lubrication brands or
types.
1. Use only high quality mineral oil with a VG grade indicated on the
customer submittal drawing.
2. Static oil level should be at the center of the lower-most roller
(Do not overfill.)
3. Complete lubrication change should be made annually.
500 750 1000 1500 2000 2500 3000 3500 4000
1
6 4
⁄2 4 4 31⁄2 21⁄2 21⁄2 1 1
1
5 4
⁄2 4 21⁄2 21⁄2 11⁄2 1⁄2 1⁄4 1⁄4
1
4
⁄2 4 31⁄2 21⁄2 11⁄2 1 1⁄2
4 4 2
4 2
1
⁄2 1 1⁄2
1
⁄2 11⁄2
Static Oil Lubrication
Grease
to be
added
at each
interval
0.50 oz.
0.75 oz.
2.00 oz.
4.00 oz.
7.00 oz.
LIMITATIONS OF WARRANTIES and
CLAIMS
Seller warrants to the original purchaser that the
goods sold hereunder shall be free from defects in
workmanship and material under normal use and service
(except in those cases where the materials are supplied
by the buyer) for a period of one year from the date of
original installation or eighteen (18) months from the date
of shipment, whichever occurs first. The liability of seller
under this warranty is limited to replacing, repairing, or
issuing credit (at cost, F.O.B. factory and at seller’s
discretion) for any pars which are returned by buyer
during such period provided that:
a. Seller is notified in writing within ten (10) days
following discovery of such defects by buyer, or
within ten (10) days after such defects should
be reasonably have been discovered, whichever
is less;
b. The defective unit is returned to seller, trans portation charges prepaid by buyer.
c. Payment in full has been received by seller or
said products; and
d. Seller’s examination of such unit shall disclose
to its satisfaction that such defects have not
been caused by misuse, neglect, improper installation,
repair, alteration, act of God, or accident.
e. Seller cannot guarantee sound pressure levels or
dBA.
No warranty made hereunder shall extend to any
seller product whose serial number is altered, effaced,
or removed. Seller makes no warranty, express or
implied, with respect to motors, switches, controls, or
other components of seller’s product, where such components are warranted separately by their respective
manufacturers. THIS WARRANTY IS EXPRESSLY IN
LIEU OF ALL OTHER WARRANTIES, EXPRESS OR
IMPLIED, WHETHER STATUTORY OR OTHERWISE,
INCLUDING ANY IMPLIED WARRANTY OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR
PURPOSE. In no event shall seller be liable to buyer for
indirect, incidental collateral, or consequential damage of
any kind. (BUYER’S FAILURE TO PAY THE FULL
AMOUNT DUE WITHIN SIXTY (60) DAYS OF DATE OF
INVOICE SHALL OPERATE TO RELEASE SELLER FROM
ANY AND ALL LIABILITY OR OBLIGATION ARISING
PURSUANT TO ANY WARRANTY, EXPRESS OR
IMPLIED, WHETHER STATUTORY OR OTHERWISE,
INCLUDING ANY IMPLIED WARRANTY OR
MERCHANTABILITY OR FITNESS FOR A PARTICULAR
PURPOSE, MADE IN CONNECTION WITH ANY
CONTRACT HEREUNDER. BUYER AGREES THAT SUCH
FAILURE TO PAY SHALL CONSTITUTE A VOLUNTARY
WAIVER OF ANY AND ALL SUCH WARRANTIES
ARISING PURSUANT TO SUCH CONTRACT.)
TWIN CITY FAN & BLOWER | WWW.TCF.COM
5959 Trenton Lane N | Minneapolis, MN 55442 | Phone: 763-551-7600 | Fax: 763-551-7601
1MPP11/09
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