masters thesis: installation, maintenance and operation ... · pdf fileinstallation,...

Installation, Maintenance andOperation Manual for

COFIMCO B/BR-Series Fans

B/BR - V2.1 - EN

July 5, 2011

AXIAL FANS FOR THE WORLD

It is recommended that this entire manual be read very intently beforeproceeding with installing the fan.

IMPORTANT: for installations of more than one fan, first, do completesetup of one single fan, and only after ensuring the perfect functioning ofthis fan (as described in manual), follow same mounting procedure with therest of fans.


ATTENTION: hub and blades of COFIMCO B/BR-Series Fans, are patented Cofimcotrademark .The content of this manual cannot be copied, reproduced or printed without writtenauthorization from Cofimco S.r.l., and should a falsification occur, Cofimco S.r.l. willprotect itself using whatever means consented by law.

Copyright c© 2009 - COFIMCO S.r.l., Pombia (NO), ITALYAll right reserved.

Manufacturer’s Declaration

Manufacturer:

COFIMCO S.r.l. via A.Gramsci 62, 28050 Pombia (NO) ITALIA

Declares that:each axial fan is manufactured in such a way to be built-in a machine or assembled

with other machineries for it to be constituted a machine in accordance with thenormative 2006/42/CE;

Declares also that:it is not consented to run the fan until the fan, the equipment in which the fan mustbe built into, or of which must become a component part of, have been declared in

accordance with the normative 2006/42/CE and with the national legislation in force.


Table of Contents

Warranty iv

1 General Informations 1

2 Installation 42.1 Required tools for assembly . . . . . . . . . . . . . . . . . . . . . . . . . 4

2.2 Fan rotation and flow direction . . . . . . . . . . . . . . . . . . . . . . . 5

2.3 Inclination of blade axis . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.4 Installation procedure for Cofimco B/BR-series Fans . . . . . . . . . . . . 6

2.4.1 Hub boss placement to driving shaft . . . . . . . . . . . . . . . . 6

2.4.2 Blades installation and pitch angle setting . . . . . . . . . . . . . 8

2.5 Seal Disk Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

3 Operating Instructions 11

3.1 Prior to start-up operations . . . . . . . . . . . . . . . . . . . . . . . . . 11

3.2 Post start-up operations . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

4 Preventive Measures for Maintenance 154.1 Maintenance and operations . . . . . . . . . . . . . . . . . . . . . . . . . 15

4.2 Temperature range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

4.3 Possible causes of vibration . . . . . . . . . . . . . . . . . . . . . . . . . 17

A Hub Removal 19

B Trouble Shootings 20

C Part List 22

Contacts 24

AXIAL FANS FOR THE WORLD COFIMCO B/BR-Series Fans

List of Figures

1.1 Type of fan installation . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.2 Identification tag format . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.3 Tag example 4267/05/24L/B3RT . . . . . . . . . . . . . . . . . . . . . . 2

2.1 Necessary tools for installing the blades . . . . . . . . . . . . . . . . . . . 4

2.2 Blade rotating clockwise . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.3 Blades axes layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.4 Hub boss with cylindrical bore . . . . . . . . . . . . . . . . . . . . . . . . 6

2.5 Hub boss with bushing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

2.6 Blades to hub installation . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2.7 Inclinometer placement . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2.8 Seal disk installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

3.1 Fan-diameter-change scheme. . . . . . . . . . . . . . . . . . . . . . . . . 12

3.2 Fastening blocks alignment . . . . . . . . . . . . . . . . . . . . . . . . . 13

3.3 Vibrations inspection positions . . . . . . . . . . . . . . . . . . . . . . . . 14

A.1 Hub removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

C.1 Parts exploded . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23


List of Tables

2.1 Bushing screw [7] torque . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

2.2 Scew type depending on hub . . . . . . . . . . . . . . . . . . . . . . . . 9

2.3 Screw torque blocks - hub (screws (8)(10) standard) . . . . . . . . . . . . 9

3.1 Minimum allowed distance blade - closest obstacle (δmin) . . . . . . . . . 11

3.2 Screw torque, bolts [16] fastening blocks - flexy element (standard bolts) . 13

4.1 Temperature range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

C.1 Part list standard hub (see Fig.C.1) . . . . . . . . . . . . . . . . . . . . . 22


Warranty

COFIMCO S.r.l. guarantees that labour and all material used in the manufacturing offans are of the highest quality.

In case of mechanical breakage within the 1st year of its functioning or 18 monthsfrom when shipped out from our establishments, and our inspectors ascertaining thebreakage was caused from defective material and/or poor workmanship, the fan willbe repaired or immediately replaced with an identical or equivalent fan free of charge.Repairs or replacements will be F.O.T. from our establishments and will not includetransportation or extra labour costs.

If ascertained that some outside interference was caused to the fan or the breakage wasprovoked by an erroneous installation and/or manhandling, Cofimco S.r.l. will ceaseall warranty. Cost of repairs done without consent from Cofimco S.r.l. will not beaccepted.

Under no circumstances will Cofimco S.r.l. be responsible for consequential or inciden-tal damage, of any type, a result from manufacturing, selling, installing or use of itsproduct.


Chapter 1

General Informations

COFIMCO B/BR-Series Fans description

The stationary adjustable pitch COFIMCO B/BR-Series Fans is a remarkable inventionbecause of its simplicity. The hub is a single component made of steel. Blades are madeup of an airfoil section in aluminum alloy or fiberglass, fastened to a steel plate throughbolting.The steel plate is anchored to the hub through blockers which are bolted toboth the steel plate and the hub. The blockers are designed in a way that is possibleto modify the fan diameter.

Air Flow

(c) B Type

Air Flow

(d) BR Type

Figure 1.1: Type of fan installation

The COFIMCO B/BR-Series Fans are available in two different configurations (seefigure 1.1 just as an example):

• Type B: fans leaning on driving shafts.

• Type BR: fans suspended on driving shafts.


2

Description fan identification numbers

All COFIMCO fans are equipped with a tag fixed on the hub to enable a clear and fastidentification.

The tag format is described on figure 1.2; an example of tag format is shown on figure1.3.

F/T Fan Type (the fan is identified by a serial number): XXXXX XX XXY XXY

Hub dimension

Hub Type

Blade Material: N: Aluminum L: Aluminum with flap F: FRP

Blade type

Number of blades

Fan Diameter (mm)

After the fan serial number there might be an extra letter, R and/or T, that represent the reverse installation layout and the special tip caps, respectively.

C/R COFIMCO reference number.

P.O. Purchase order number.

I Item number within the job.

A° Blade pitch angle in degree.

Figure 1.2: Identification tag format

COFIMCO S.R.L. - ITALY

Via A. Gramsci, 62 - 28050 POMBIA (NO)

F/T

C/R

P.O.

I

A°

BLADE PAT. N° 4618313

HUB PAT. N° 4715784

4267/05/24L/B3T

12345/678

PO123456

E-1234

10.5

Figure 1.3: Tag example 4267/05/24L/B3RT

Tag shown in example (Fig. 1.3) refers to a fan with a diameter of 4267 mm, made upof 5 blades, each with an Aluminum profile type 24L (with flap) with special T caps,


3

hub type B3. Reference Job number 12345/678, customer’s purchase order referencenumber PO123456, Item number within Job E1234 and blade pitch angle 10.5◦.

ATTENTION: tag referred above is just an example and does not in any way corre-spond to any data referred to an identification tag of any purchased fan.

ATTENTION: data shown on identification tag must always be referred when order-ing spare parts.

Balancing

If not otherwise requested from the beginning, all Cofimco S.r.l. fans are balanced inthe following manner:

• Dynamic fan balancing, with a balance degree of G = 6.3 according to ISO 1940/1,in the case the fan is shipped out already assembled.

• For a fan dispatched disassembled, the hub is dynamically balanced while theblades are statically balanced so that the reassembled unit correspond to a balancedegree of G = 6.3 according to ISO 1940/1. In this case, the blades have the samestatic moment, therefore they can be placed in any order on the hub (the bladesof the same item are interchangeable).

Storage

As soon as a Cofimco fan is delivered it is very important to administer an accurateinspection in order to verify for possible damages due to transportation. In such cases,present a claim to the transportation company and mention on the claim the relativedocuments accompanied, such as, bill of lading, insurance certificates (if any), etc.

Also, as soon as fan is delivered, please insure that components are exactly what wasordered and delivered. In a case where goods are not in compliance with what ordered,contact Cofimco within 2 weeks of delivery.

If a fan is not immediately installed, we recommend that it be kept in a closed dry place,and not place any heavy material whatsoever on the blades. In the case of storage fora long period of time, before putting the product in action, please verify the conditionof protective layer of anti-corrosion on all surfaces performed on machines.


Chapter 2

Installation

This manual refers to COFIMCO B/BR-Series Fans, installation conditions can varyin different situations.

2.1 Required tools for assembly

For assembling a fan, the following tools are required:

• Dynamometric spanner (torque wrench fig. 2.1(a)) required for fastening the boltsto a set screw torque.

• Goniometric level(inclinometer fig. 2.1(b)) required for setting the blade pitchangle to the angle of design, following the procedure described in this chapter. Theaccuracy of the inclinometer must be at least ±0.5◦ (max admissible tolerance).

(a) Torque wrench (b) Inclinometer

Figure 2.1: Necessary tools for installing the blades

Upon request COFIMCO S.r.l. has available for sale the necessary tools for installation.


2.2 Fan rotation and flow direction 5

2.2 Fan rotation and flow direction

The direction of fan rotation is correct when air flow moves from pressure side to suctionside. In the example seen in figure 2.2 rotation is clockwise, seeing the side that receivesair flow; upon request, Cofimco S.r.l. can supply fans with counterclockwise rotation.

Axi

sof

rota

tion

Clockwiserotation

Blade Axis

Air FlowDirection

Figure 2.2: Blade rotating clockwise

2.3 Inclination of blade axis

Cofimco fan blades may present, respect to the plane perpendicular to the axis ofrotation, a small geometric angle in the direction from where the air flow comes from(see fig. 2.3).

Because of this angle, the centrifugal force generates a moment of flexure opposite tothat generated from trust, reducing stress which the blades can be subject of. It istherefore necessary, while installing, in the presence of this angle that the blade axisbe turned toward where the air flow is coming from.

Air Flow

Plane of RotationCentrifugal ForceAxis of Rotation

Trust Moment due toCentrifugal force

Blade Axis Inclination

Moment due to Trust

Figure 2.3: Blades axes layout


2.4 Installation procedure for Cofimco B/BR-series Fans 6

2.4 Installation procedure for Cofimco B/BR-series Fans

After ensuring that all electrical contacts have been disconnected and that the motorcan not in any way be started inadvertently, one can proceed with the assemblingdescribed herewith.

2.4.1 Hub boss placement to driving shaft

COFIMCO supplies two different types of hub boss:

1.A) Hub boss with cylindrical bore: in this case the hub is directly anchored tothe driving shaft, follow figure 2.4 for the installation procedure.

4 5

3

1

2

Figure 2.4: Hub boss with cylindrical bore

Coat the driving shaft [1] with a thin layer of grease. If supplied, put the spacer[2] in the driving shaft until it touches the driving shaft’s shoulder. Fit the hub[3] through the driving shaft until it touches the driving shaft’s shoulder (or thespacer if supplied). Make sure the hub lateral oblique faces placed as on figure 2.4(”facing” down). The driving shaft end, when the hub boss is in contact with itsshoulder, should be at least 2 mm inside the hub bore (5 mm are suggested). Thisto avoid fans vertical displacements when the screw [5] is tightened. Put then thewasher [4] to the hub boss and fasten the screw [5] to the driving shaft.

NOTE: screw [5] is not supplied by COFIMCO.



1.B) Hub boss with bushing: follow figure 2.5 for the installation procedure.

ATTENTION: in this case the driving shaft must not be coated withany grease.

7 61

3

Figure 2.5: Hub boss with bushing

Fit the bushing [6] into the driving shaft [1] until it reaches the desired location;the driving shaft end must not be inside the bushing. Install the hub boss to thebushing making sure the screw holes of the two items are aligned. Make sure thehub lateral oblique faces placed as on figure 2.5 (”facing” down). When aligned,fasten the hub to the bushing with the screw [7] torque defined on table 2.1.

Bushing TypeScrew Torque

N · m Lb · ft

P2 21.0 16.0Q1 e Q2 39.3 29.0R1 e R2 39.3 29.0S1 e S2 94.9 70.0

Table 2.1: Bushing screw [7] torque

ATTENTION: do not start the fan with the bore screw (hub with cylindricalbore) or the bushing screws (hub with bushing) fastened incorrectly.



2.4.2 Blades installation and pitch angle setting

ATTENTION: before starting with the blades installation clean all the couplingsurfaces.

98

16

17

18

1110

Blade Axis

Blade Pitch Angle Adjustment

5 mm

90°

Figure 2.6: Blades to hub installation

Proceed with the installation following procedure and taking as a reference figure 2.6:

1. Fit the blade to hub through the fastening devices (screw [8] [10], washers [9][11]) as shown on figure 2.6. The screws have to be fastened with a screw torquethat allow the blade pitch angle setting. It is suggested to apply Loctite 270 orequivalent to lock the screw threads.

2. Place the inclinometer to the blade upper part at 5 mm from the blade ends andperpendicular to blade main axis as shown on figure 2.6. In case of a large profile(the inclinometer length is not enough), it is necessary to use a flat rod long enoughto reach the blade leading and trailing edges and then lean the inclinometer onit. See figure 2.7 for a correct placement.

Not right placement Right placement Right placement

Figure 2.7: Inclinometer placement

3. Rotate the blade until it reaches the requested pitch angle (A◦) written on fanidentification tag. The maximum admissible tolerance is ±0.5◦



4. Fasten the screws [8] [10] with the torque wrench. The screw torque depends onbolts classes, this is reported on bolts head. For standard bolt 8.8, 10.9 Class orA4/80 use the screw torques given on table 2.3 depending on the hub type (seetable 2.2).

NOTE: the hub type is indicated on the identification tag while the bolts class isstamped on screw head and reported in the documentation’s part list.

Hub Type Screw [8] Screw [10]

B1 M14 M12B3 M16 M14B6 M20 M20

Table 2.2: Scew type depending on hub

ATTENTION: the data regarding the bolts type is reported in the documentation’spart list.

Screw TypeScrew Torque

8.8 Class 10.9 Class A4/80

N · m Lb · ft N · m Lb · ft N · m Lb · ft

M12 75.4 55.6 - - 63.8 47.1M14 119.3 88.0 124.6 91.6 101.0 74.5M16 179.3 132.2 194.2 143.2 151.4 111.7M20 349.7 257.8 400.3 295.1 295.3 217.8

Table 2.3: Screw torque blocks - hub (screws (8)(10) standard)

Repeat the previous operations for each blade. Before starting the pitch angle settingoperation for a new blade, turn the fan until the new blade is located at the sameposition inside the fan ring as the previous ones. This to compensate any slight verticaldeviation from fan axis rotation.

ATTENTION: in case of a structure equipped with several fans, beforesetting blade design pitch angle to all fans , set the pitch angle on one fanonly, and follow the operating instructions of chapter 3.


2.5 Seal Disk Installation 10

2.5 Seal Disk Installation

For the installation of seal disk follow the procedure given below taking as referencethe figure 2.8.

NOTE: B1 hub does not have a seal-disk.

12A

3

13

15

14

(a) B3 hub configuration

12B

3

13

15

14

(b) B6 hub configuration

Figure 2.8: Seal disk installation

1. Place the seal-disk spacer [12A] or [12B] on the hub B3 or B6, respectively.

2. Place the seal disk [13] on top of the spacer.

3. Fasten the seal-disk to the hub through the M8 screw [15] and washer [14]; it issuggested a screw torque of 22.3 N · m (16.5 Lb · ft) for screws 8.8 Class, or ascrew torque of 14.2 N ·m (10.5 Lb ·ft) for screws A4/A2 - 70. The data regardingthe bolts type is reported in the documentation’s part list.


Chapter 3

Operating Instructions

3.1 Prior to start-up operations

1. Before running the fan be aware that the fastening blocks [17] [18] are anchoredto the hub, if there is gap check the screw torque of the screws [8] and [10] (Fig.2.6).

2. Identify blade static deflection δs (fan at rest) and the blade dynamic deflectionδd (fan running) from the fan rating sheet. In the case where the static deflectionis higher than dynamic one rotate manually the fan for one entire revolution andcheck that the distance between the blade’s lower point and closest obstacle (δ)is greater than distance δmin given on table 3.1 (δmin depends on fan diameter).If static deflection is smaller than dynamic one rotate manually the fan for oneentire revolution and check that the distance between the blade’s lower point andclosest obstacle (δ) satisfy the following equation:

δ ≥ δmin(Table 3.1) + [δd − δs]

Fan Diameter (mm)Hub Type δmin

From to

0 4000 B1 1500 3999 B3 150

4000 4881 B3 2000 5490 B6 200

5491 6200 B6 250

Table 3.1: Minimum allowed distance blade - closest obstacle (δmin)


3.1 Prior to start-up operations 12

ATTENTION: the distance between the blade’s lower point and closestobstacle (δ) is valid for wind speed up to 45 m/s.

3. Rotate manually the fan to check that the gap between the blade tip and the fanring (x) is within the design ratio x/D, where D is the fan diameter. The gapbetween the blade tip and the fan ring has to be measured along the blade mainaxis. ATTENTION: the gap measurement between the blade tip and the fanring has to be done taking into consideration the difference between the static andthe dynamic deflection; if the static deflection is bigger than that dynamic, theblade has to be lifted up of a distance equal to δs − δd; if the static deflection issmaller than that dynamic, the blade has to be moved down of a distance equalto δd − δs.

NOTE: the static and dynamic deflections are indicated in the fan rating datasheet.

In the case where the gap between the blade tip and the fan ring (x) is not thatexpected, the fan diameter could be reduced acting on fastening blocks [17] and[18] between blade and hub, as shown on figure 3.1, unscrewing bolts [16].

17

16

16

FlexyElement 17

16

16

16

17

18

16

17

18

FlexyElement

Figure 3.1: Fan-diameter-change scheme.

ATTENTION: once bolts [16] are unscrewed it necessary to fasten them backat the proper screw torque, for standard bolts use screw torques given on table3.2 making use exclusively manual tools; therefore the use of any automatic toolis forbidden.

ATTENTION: the diameter change has to be the same to all blades and thefastening blocks alignment has to be that showed on figure 3.2.

ATTENTION: the data regarding the bolts type is reported in the documenta-tion’s part list.

4. Check that blade axes agree with those defined on section 2.3.

5. Check gear box oil level and belt tension to be as indicated by the manufacturer.

6. Remove all tools from area.

7. Connect motor to power supply.


3.1 Prior to start-up operations 13

Slotted Block

16 Blocks Lateral Surface

17

18

Figure 3.2: Fastening blocks alignment

Bolt TypeScrew Torque

(Hub) 8.8 Class 10.9 Class A4/80

N · m Lb · ft N · m Lb · ft N · m Lb · ft

M10 (B1) - - 74.4 54.9 - -M12 (B3) - - 124.3 91.7 - -M16 (B6) 241.7 178.2 296.3 218.4 151.4 111.7

Table 3.2: Screw torque, bolts [16] fastening blocks - flexy element (standard bolts)

8. Start the fan for few second and then switch it off. While the fan is still turning,check that the direction of the blade rotation is correct as defined on section 2.2.


3.2 Post start-up operations 14

3.2 Post start-up operations

1. Check the power absorption, if excessive, reduce gradually the blade pitch angleuntil the desired power absorption is reached. If lower than expected, increasegradually the blade pitch angle until the desired power absorption is reached.Update the new pitching angle on the fans of the same structure.

NOTE: a pitch angle trim of few degrees, respect to that of design, has to beconsidered normal.

ATTENTION: the power absorption varies inversely to air temperature.

2. Check that vibration level, as in the positions shown on figure 3.3, does not exceedthe most restrictive amplitude values between the limits imposed by the normativeof the structure where the fan is installed and the limit of 7 mm/s RMS (overall)measured in the frequency range 0 : 50Hz; above 50Hz and until a frequencyrange that include all the structure forcing frequencies, the limit decrease to 0.5mm/s RMS (overall). In the case one of the two limits is exceeded, shut the fandown and trace the cause of such an excessive vibration by referring to section4.3.

ATTENTION: the vibration-limit is valid for vibrations that occur along or-thogonal axis, hence vibration that remains constant along those axis (it is notvalid for rotational vibrations).

Figure 3.3: Vibrations inspection positions

3. After one working hour check the hub bolts [8] [10] screw torque.

4. Repeat the bolts [8] [10] screw torque check after 24 working hours from thestart-up.


Chapter 4

Preventive Measures for Maintenance

4.1 Maintenance and operations

A Inspect periodically the overall fan conditions.

Inspection time interval depends on fan operating conditions and may vary froma minimum of two weeks to a maximum of six months. During these inspectionscheck the following:

• screw torque;

• corrosion of fasteners;

• general condition of blades surface and flexible elements.

It may be necessary to clean the rotor blades in order to ensure the fan properbalance.

B Ice formation on the blades of operating fans must be strictly avoided.

C The presence of ice on the blades of a still fan must be removed prior to start-up to avoid damages. Snow formed on a still fan must be periodically removed,according to the abundance of snow accumulated.

D For installations with two-speed motors, when stepping down from high speedto low speed, the motor must be turned off for a suitable duration so that thefan rotation speed has slowed below the low speed full RPM, before the motor isreengaged at the low speed setting.

E If the rotation direction has to changed stop the fan completely before changingit.

F Check the vibration level in the positions shown in figure 3.3 at regular breaks.


4.2 Temperature range 16

G Check periodically the painted parts to seek for any damages due to corrosion. Inparticular, inside the Cooling Towers, the blade leading edge is subject to heavycorrosion; for the latter case it is recommended an inspection every six months.Restore any corrosion damages, in particular those on blade leading edge.

The vibration level, as in the positions shown on figure 3.3, does not exceed the mostrestrictive amplitude values between the limits imposed by the normative of the struc-ture where the fan is installed and the limit of 7 mm/s RMS (overall) measured inthe frequency range 0 : 50Hz; above 50Hz and until a frequency range that includeall the structure forcing frequencies, the limit decrease to 0.5 mm/s RMS (overall). Inthe case one of the two limits is exceeded, shut the fan down and trace the cause ofsuch an excessive vibration by referring to section 4.3. It is suggested to record thevibrations in order to compare it to the previous one. For a correct comparison themeasurements have to be done always in the same location and in the same manner.During vibration analysis observe the standard safety procedure, in particular do notget close to a running fan but place the transducers (accelerometer) with a still fan andmake the measurements from a safety location.

NOTE: the vibration level is a good indicator of the plant conditions. It is thereforeopportune to make these measurements frequently (e.g. once a month).

ATTENTION: the vibration-limit is valid for vibrations that occur along orthogonalaxis, hence vibration that remains constant along those axis (it is not valid for rotationalvibrations).

4.2 Temperature range

COFIMCO fans are designed to operate at the following temperatures:

- 40°C (-40°F) with standard materials Min

Max

Aluminum blades: + 105°C (+ 221°F) Fan running Frp blades: + 80°C (+ 176°F) Fan running + 105°C (+221°F) Fan at rest

Table 4.1: Temperature range


4.3 Possible causes of vibration 17

4.3 Possible causes of vibration

The actual causes of vibration may vary considerably, some of the most common arethe following:

A Unbalance of one or more blades: the vibration caused by blade imbalance occurson fan rotation plane with a frequency equal to the fan RPM and at an amplitudelinearly dependent to the degree of imbalance and the square of the rotationalspeed.

B Blade pitch angle not included in the ±0.5◦ tolerance: this condition causes vi-bration outside the fan rotation plane at a frequency equal to the fan RPM andat an amplitude which is dependent on the square of the rotational speed.

C Blades too close to supports (periodic aerodynamic turbulence):this condition is characterized by vibration outside fan rotation plane at a fre-quency equal to the product of the number of fan blades and RPM. The amplitudedepends upon the extent of the aerodynamic turbulence.

D Resonance between one of the possible forcing frequencies of the fan and one ormore of the vibration modes of the structure on which it is installed.

The main forcing frequencies generated by the fan, normally correspond to thefollowing frequencies:

• fan RPM;

• product of fan RPM and the number of blades;

• product of fan RPM and the number of structural supports capable of gen-erating aerodynamic turbulence (if they are arranged in an axial-geometricmanner).

E Vibration transmitted by the structure on which the fan is installed: the frequen-cies of such vibration depend on both the external forcing frequencies and theresonant frequencies of the structure.

F Resonance of the blades with one of the possible forcing frequencies: in the vastmajority of cases the vibration occurs outside of the blade rotation plane.

G Misalignment of the drive shaft: this generates vibration with a frequency that isone or two times the RPM. In most cases the vibration occurs outside the bladerotation plane.

H Loosening of blade and/or speed reducer fastening bolts: the fan behavior underthese circumstances is totally unpredictable, as it depends on the extent andlocation of the loosening.

I Output-shaft’s bearing that is worn out: this condition generates vibration on theblade rotation plane at a frequency equal to the rotor RPM.


4.3 Possible causes of vibration 18

J The fan and/or the structure bolts are not tightened: in this case all the boltshave to be tightened.

K The draining holes of the blades are obstructed: it is necessary to open them back.

L Incorrect hub installation: it is necessary to re-install the hub as described onsection 2.4

ATTENTION: the amplitude of the fan vibration is determined by the stiffness ofits support. Vibration that would not be critical to a fan supported by a sufficientlyrigid structure is amplified by an overly flexible support. This support stiffness mayalso cause unexpected variations in the resonance frequency of the blades.


Appendix A

Hub Removal

ATTENTION: before removing the hub be aware that the motor electrical sourcesare disconnected, therefore the motor will not be able to start.

The hub removal operation can be done using an hub extractor (see example fig. A.1)not supplied with the fan.

The fan hub may be extracted with or with out the blades installed. During removaloperation the fan has to be belted in order to avoid its fall after having removed theanchoring bolts.

After have removed the hub anchoring screw, place the hub extractor as shown onfigure A.1 fitting between the screw [B] and the shaft end a round plate [A] of diameterslightly smaller than hub bore and a thickness of at least 5 mm (this to prevent drivingshaft damages). Fasten the extractor to the hub through the screw [B] until the hub isfree from the driving shaft.

(a) B-Extractor

B

A

(b) Hub removal scheme

Figure A.1: Hub removal


Appendix B

Trouble Shootings

TROUBLE SHOOTINGS

Situation Possible Causes Possible Solutions System congestion. Clean the entire system

Check the real obstacles area and the inlet shape towards the original design.

Obstacles to the air flow. In dry-coolers the minimum free height of the inlet area has to be 1 time the fan diameter at least; this height has to be higher in the case of multiple units in line.

Static pressure higher than specified one .

Increase blade pitch angle (till 3 deg. after having checked the data sheet selection).

Blade pitch angle changed. (e. g. bolts [8] [10] not tightened at the right torque).

Set the right pitch angle and refer to the operation manual to set the right torque of screws and bolts.

Low Air Flow Low Power Absorption

Temperature higher than that of design.

Increase blade pitch angle (till 3 deg. after having checked the data sheet selection).


21

Situation Possible Causes Possible Solutions

Temperature lower than that of design.

Decrease the blade pitch angle (till 3 deg. after have checked the data sheet selection). High power absorption

Static Pressure lower than that of design.

Decrease the blade pitch angle (till 3 deg. after have checked the data sheet selection).

Screws and bolts of the fan and/or the structure loosened. Torque all screws and bolts. Rubbing between the blades

and the fan ring Fan not centered. Tip clearance too small.

Center the fan. Increase the fan ring diameter.

Scratch or little damages … Contact Cofimco. Thin crack on a blade surface … Contact Cofimco.

Unbalance of one or more blades. Contact Cofimco.

Blade pitch angle not included in the 0.5 deg. tolerance. Set right blade pitch angle.

Blades too close to the supports (periodic aerodynamic turbulence).

Contact Cofimco.

Resonance between one of the possible fan forcing frequencies and one or more of the vibration modes of the structure on which it is installed.

Contact Cofimco.

Vibration transmitted by the structure on which the fan is installed.

Contact Cofimco.

Resonance of the blades with one of the possible forcing frequencies.

Contact Cofimco.

Misalignment of the drive shaft. Realign the drive shaft. Worn output shaft bearing Contact the supplier. The fan and/or the structure bolts are not tightened

Tighten screws and bolts at the right torque.

High vibration level

The draining holes of the blades are obstructed Open the draining holes.

In case of any problem contact COFIMCO S.r.l. specifying the order number indicatedon the fan identification plate.


Appendix C

Part List

ATTENTION: the part list refers to a standard B/BR-Series fan, for special appli-cation the actual part list is that included with the fan documentation.

Part List Item Description Item Description

1 Driving Shaft 12A Seal disk spacer (if supplied) 2 Spacer (if supplied) 12B Seal disk spacer (if supplied) 3 Hub 13 Seal disk (if supplied) 4 Washer 14 Washer 5 Screw (not supplied by cofimco) 15 Screw 6 Bushing (if supplied) 16 Screw 7 Bushing Screw (If supplied) 17 Upper Block 8 Screw 18 Lower Block 9 Washer 19 FLEXY Element 10 Screw 20 Blade 11 Washer

B−BR Series fans standard components

Table C.1: Part list standard hub (see Fig.C.1)


23

15

14 13

5

416

9

8

17

18

1011

3

2

6

1

1920

12B

12A

7

Figure C.1: Parts exploded


Contacts


COFIMCO S.r.l.Via A. Gramsci, 62

28050 Pombia (NO)Italy

Tel. +39 0321/968311Fax. +39 0321/958992

[email protected]://www.cofimco.com

mailto:[email protected]

http://www.cofimco.com

masters thesis: installation, maintenance and operation ... · pdf fileinstallation,...

Documents