service manual e-series cofimco

Service Manual

Howden 24-07.030r04E 1/25

Installation and Maintenance

E-series Axial Flow Cooling Fans

Warning

Failure to comply with these instructions could cause serious bodily harm or property damage and will void the warranty.

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Service Manual

INDEX

I. General Information ........................................................................................................................ 3

Introduction ........................................................................................................................................ 3 Description ......................................................................................................................................... 3 Options / Accessories (at extra cost) ................................................................................................. 3 Field Service ...................................................................................................................................... 3

II. Receiving / Handling / Storage / Disposal .................................................................................... 4 Fan identification ............................................................................................................................... 4 Receiving and unloading ................................................................................................................... 5 Handling ............................................................................................................................................. 5 Storage .............................................................................................................................................. 5 De-commissioning ............................................................................................................................. 6 Exploded view and part list ................................................................................................................ 7

III. Installation ..................................................................................................................................... 8 Required Tools .................................................................................................................................. 8 Rotation and flow direction ................................................................................................................ 8 Preparation ........................................................................................................................................ 8 Coupling flange with parallel bore ..................................................................................................... 9 Coupling flange with tapered bushing ............................................................................................... 9 Hub-plate installation ....................................................................................................................... 10

Blades installation..........................................................................................................................12 Minimum tip-clearance .................................................................................................................... 14 Impeller diameter reduction ............................................................................................................. 15 Retaining plate ................................................................................................................................. 15 Balancing ......................................................................................................................................... 16

IV. Commissioning ............................................................................................................................ 16 V. Preventive Maintenance .............................................................................................................. 18 VI. Contact Howden ......................................................................................................................... 19 VII. Trouble Shooting ....................................................................................................................... 20 VIII. Overview Tightening Torques ................................................................................................. 23 IX. Hardware Overview .................................................................................................................... 24 X. Guideline for acceptable vibration levels of cooling fans in application category BV-3 (according ISO 14694) ...................................................................................................................... 25 XI. Document Version Control ........................................................................................................ 25

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I. GENERAL INFORMATION Introduction

This manual provides information necessary to install, operate and maintain E-series axial flow cooling fans. Maintenance guidelines and procedures are given so that your equipment will operate efficiently, with a minimum of re-pair or replacement requirements.

Description

Howden E-series fans are most widely used and are available in three different blade pro-files, ENF, ELF & ELFA. Whether you are looking for a highly efficient impeller and/or a low noise solution, the E-series offers you a choice. The fibreglass reinforced polyester blades have an integral shaft, which eliminates concentration of stress at mechanical joints. The FRP blade material offers superior damp-ing of mechanical vibrations and of structure borne noise compared with metal blades, pro-longing the fans lifetime. The fan blades are connected to a polyurethane coated steel hub with aluminium clamping pieces and A2 stainless steel or ST8.8 galvanised steel U-bolts, nuts and washers for an easy installation and manual blade pitch variation. The impellers are connected to the drive shaft by means of a polyurethane coated cast iron cou-pling flange, with a cylindrical bore and electro-galvanised hardware.

Howden E-series impellers are in compliance with EC directive 94/9EC (ATEX 100) for the equipment of level group II, Category 2, poten-tially explosive environment class 01. Also re-spect the instructions in paragraph IV commis-sioning.

Note: The nomenclature is cooling fans, however Howden supplies impellers only. Im-pellers are components in the sense of Euro-pean Machinery Directive 98/37/EC.

Allowable operating temperature Min. Max. All diameters - 20C + 65C - 4F + 149F

Allowable incidental upset temp. (

Service Manual

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II. RECEIVING / HANDLING / STORAGE / DISPOSAL Fan identification The fan identification code allows identification of the main characteristics of the fan. You can find this code on the order acknowledgement and packing list included with the shipment. FAN 30ENF6 EP Another example: FAN 8910ELF8 Identifies an ELF fan with a diameter of 8910 mm, 8 blades and without leading edge protection (EP) The impellers are provided with a product identification plate fixed to the hub plate according the example below. The unique order number permits future identification of the fan supplied.

Leading edge protection for wet cooling tower applications

Number of blades: 3,4,5,6,7,8,9

Impeller type: ENF, ELF, ELFA

Fan diameter: metric or imperial (>100 = mm,

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Receiving and unloading

Upon unloading this equipment, inspect it for damage. If damage occurred, file a claim im-mediately against the carrier and mark the bill of lading accordingly.

Superficial transport damages like scratches or small holes may be repaired with touch-up material (PU filler, e.g. Sikaflex 252).

All consignments are accompanied by a packing list with the following data:

Order number of the Customer and of Howden.

Impeller type (fan identification code)

Parts supplied by Howden.

The delivered goods shall be checked upon arrival for full compliance with the order and/or the parts count and description stated on the packing list.

Shortages should be reported to your How-den Contract Engineer within 2 weeks from receipt of shipment at destination.

Handling

Fan blades of E-series impellers larger than 26 ft. are packed in so-called bunk beds or specially developed transport frames.

Figure 1 The width of these crates suits standard con-tainer dimensions. Fan blades that will be transported by container sea-freight, are equipped with and hoist eyes (see figure 2),

to allow easy container loading / unloading. Through these hoist eyes, one can pull the bunk beds from the container without dam-aging the fan blades or the crates.

Figure 2

The fan blades can be lifted from the packing by placing a single sling around the blade. Position the sling as such that the blade tip is somewhat hanging down which makes it easier to move the blades around.

Fan blades of impellers smaller than 26 ft., are packed in strong wooden cases or crates.

Storage

If not installed immediately, it is recom-mended to store the impeller in a dry and shaded area.

For long-term storage (in excess of 6 months) it is necessary to check the condition of the corrosion protection agent on all machined surfaces.

Reapply or repair where necessary, using an acid-free corrosion protection agent (e.g. Esso Rust ban 397 or equivalent).

You may stack the bunk beds to a maximum of 3 high. Do not allow any heavy materials of any kind to be stored on top of the blades.

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De-commissioning In accordance with our ISO14001 certified environmental management system, our cooling fans can easily be disassembled after de-commissioning. Their metal components and polyethylene fan casings are highly suitable for recycling. Since no viable recycling procedure for reinforced plastics exists, fan blades need to be shredded and incinerated or used as land-fill. The inert nature of the materials used will prevent chemical pollution of soil and ground water in case of in land-fill.

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Exploded view and part list

Figure 3 Figure 4

Item Description Material (standard construction) Quantity 1 U-bolt Stainless steel A2/ steel 8.8 2 / blade 2 Upper clamping piece Aluminium 2 / blade 3 Lower clamping piece Aluminium 1 / blade 4 Washer Stainless steel A2/ steel 8 4 / blade 5 Nut Stainless steel A2/ steel 8 4 / blade 6 Blade Fibreglass reinforced polyester - 7 Hub plate Polyurethane coated mild Steel 1 8 Coupling flange bolt Steel class 8.8 electro-galvanised 8 9 Washer Electro-galvanised 16 10 Nut Electro-galvanised 8 11 Coupling flange Nodular cast iron polyurethane coated 1 12 Split tapered bushing Manufacturers standard 1 (optional) 13 Bolt Manufacturers standard 3 (optional) 14 Retaining plate Polyurethane coated steel 1 (optional) 15 Central bolt M16 or M20 or M24 Steel class 8.8 electro-galvanised 1 (optional) 16 Washer Electro-galvanised 1 (optional) 17 Gasket Rubber 1 (optional) 18 Key - 1 (optional) 19 Key Not supplied by Howden

Table 2

1

2 16

3

4 5 6

15

14

9

8

12

10

9

11

13 7

18 19

17

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III. INSTALLATION Required Tools Torque wrench (check tightening torques

for the correct model)

Socket and wrench

Inclinometer

Straight edge:

Minimum length > blade width

Rotation and flow direction Standard rotation is clockwise when viewed into the air-stream. See figure 5.

Figure 5

Preparation

Clean all mating surfaces between shaft, ta-pered bushing (if applicable) and fan hub. All corrosion preventive coatings should be re-moved.

Check the following before parts shall be as-sembled:

Drainage hole at the blade tip and blade shoulder shall be open

Make sure the drive shaft is properly cen-tred with respect to the fan casing. Also check if the shaft is vertical within the pre-scribed tolerance.

Check the concentricity of the driver shaft end before mounting the impeller. The im-peller should not be mounted if the con-centricity error exceeds 0.02 mm (0.0008) see figure 6.

Figure 6

Flow

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Coupling flange with parallel bore a) Check if the shaft and bore diameters are

according to specification. The standard execution has a H7 fit.

b) Slightly lubricate the shaft, the key, and the bore of the hub with grease.

c) Locate the key (19) into the drive shaft (figure 7).

d) To slip the coupling flange over the shaft we advise you to uniformly heat up the coupling flange up to maximum 120 C (248 F) by means of a hot plate, electric induction or oil bath, until a 0.15mm dif-ference in diameter is reached. Wear protective gloves during this operation.

e) Slip the coupling flange (11) onto the drive shaft and check the key for proper fit. Be sure the coupling flange is com-pletely through the shaft against the shaft shoulder.

f) For reverse coupling flange configuration: (e.g. impeller hanging below the driver) Install the retaining plate (14) with gasket (17) and secure it to the shaft with the lock washer (16) and the central bolt (15). Supply of retaining plate items 14, 15, 16 and 17 by Howden is optional. Item 19 (key) is not supplied by Howden. For torque values of the retaining plate bolts see table 7 on page 22.

Figure 7

Coupling flange with tapered bushing (Supply of coupling flange with tapered bushing is optional). a) Do not lubricate bushing, coupling flange

bore or hardware. Use of lubricants can cause coupling flange damage.

b) Slip the bushing onto the drive shaft and check the key (19) for proper fit (figure 8 on page 10). Be sure the shaft is com-pletely through the bushing. Keep a bolt length as minimum distance X between bolts (13) and flange of the drive (figure 9 on page 10).

c) Lock the bushing on the shaft by tighten-ing the setscrew in the flange. Support the bushing with a sleeve to prevent it from sliding down during assembly.

d) Install the coupling flange onto the bush-ing. Start bolts (13) by hand turning just enough to engage threads.

e) Keep tightening them as equally as possible, in several steps, while drawing the hub onto the bushing until the bush-ing tightly grips the shaft.

f) Tighten the bolts to the torque shown in table 3. Do not over-torque. Excessive torque can cause coupling flange or bushing damage. Some gap must remain between the flange of the bushing and coupling flange in properly tightened as-sembly.

Torque value for bolts

tapered bushing to coupling flange Class 8.8 (A3B)

Bolt size (bushing type)

Torque (Nm)

Torque (lb.ft)

5/16 (P2) 22 16 3/8 (Q2, R2) 39 29

(S1) 95 70 5/8 (U1) 190 140

3/4 (W1, W2) 339 250 Table 3

14

19

11

15

16

17

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g) For reverse coupling flange configuration: (e.g. impeller hanging below the driver) Install the retaining plate (14) with seal ring (17) and secure it to the shaft with the lock washer (16) and the central bolt (15). Supply of retaining plate items 14, 15 and 16 by Howden is optional. For torque values of the retaining plate bolts see table 7 on page 22.

Figure 8

Figure 9

Hub-plate installation a. Mount the hub-plate (7) onto the machined

surface of the coupling flange (11) (fig. 10). Figure 10

b. Place the bolts (8) with washers (9) and

tighten the nuts (10) alternating, keep tight-ening on all of them as nearly equal as pos-sible.

c. Tighten the nuts (10) to the torque shown in figure 11 on the next page. (For the correct thread size refer to table 8 on page 23). Use original Howden hardware exclusively (the nuts are treated with special low fric-tion coating).

18 19

13

12

11

14

16

15

17

9

11

7

9

8

10

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Figure 11

Tip: You may also choose to install the fan blades onto the hub-plate before bolting the complete impeller onto the coupling flange.

Figure 12 Tip: The hub-plate may be installed with the clamping pieces either at the flow inlet or flow outlet side. This may help to correctly position the fan blades in the fan casing (see figure 12). This configuration is only possible when the coupling flange is fitted on the opposite side from the lower clamping pieces or in a configu-ration like figure 12, for impellers with a diame-ter 9 (2743 mm). If you prefer to use a configuration with the coupling flange fitted in between the lower clamping pieces, for impellers smaller than 9 ft., than please ask Howden at order placement.

Standard bolts (8.8, A3B) Stainless steel (A4) Nm lb.ft 75 55 185 136 360 266 625 461 1260 929 2600 1918

Thread size M12 M16 M20 M24 M30 M42

Important

Impellers with a diameter smaller than 4455 mm or 14 feet are balanced according to a certain hub-plate configuration. Check the sticker on the hub-plate to make sure the installation corresponds to the applied balancing method (refer to balancing section on page 15).

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Blades Installation Impellers 4455 mm / 14 feet Impellers up to and including a diameter of 4455 mm or 14 feet are balanced in assembly and have a unique balancing code. Check if the blades share the same project

number. The blades must be positioned in the lower

clamping pieces with corresponding bal-ancing code.

(For position of these numbers see figure 13). Impellers > 4455 mm / 14 feet, and

Check if the blades share the same project number.

odd number of blades Impellers with an odd number of blades -require the blades to be installed as sets.

The blades must be installed on a hub-plate as sets. A blade-set share the same 2- or 3-digit figure in the balancing code (e.g. 11A, 11B, 11C, 11D, 11E in case of a 5-bladed impeller).

(For position of these numbers see figure 13). Impellers > 4455 mm / 14 feet, and

Check if the blades share the same project number.

even number of blades Impellers with an even number of blades re-quire the blades to be installed in pairs.

The blades must be installed on the hub-plate in pairs, with the paired blades posi-tioned opposite each other. Always position blade A facing blade B. Pairs share the same 2- or 3-digit figure in the balancing code (e.g. 31A facing 31B, 32A facing 32B, 33A facing 33B in case of a 6-bladed im-peller).

(For position of these numbers see figure 13). Note: For impellers > 4455 mm / 14 feet the blade sets can be installed on any position of

a fan hub, provided that the blade sets will be installed in the sequences spelled out in this paragraph. The blades are marked with a unique blade number, a project number and a balancing code (see figure 13). Figure 13

Procedure: a. Place a blade in a suitable lower clamping

piece of the hub plate, considering the in-stallation rules as described in this para-graph.

b. Place the upper clamping pieces over the blade stem and insert the U-bolts through the holes of the hub-plate. Place the washers and hand-tighten the nuts just enough to keep the blade in place. For the standard configuration (blades on top of hub plate) we recommend to insert and tighten the inner U-bolt first (next to the collar). When the blades are hanging un-derneath the hub-plate we recommend in-

Balancing code

Blade nr

Project nr.

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serting the outer U-bolt first. Check if the upper clamping piece is mounted horizontally by measuring the gap A an B between the lower and upper clamping piece (see figure 14).

Figure 14 c. Tighten the nuts alternating such that the

blade can still be somewhat turned in the clamping piece.

d. Make sure that the blade stem collar is flush against the lower clamping piece, which can be achieved by pulling the blade outwards.

e. Place a straight edge or a sufficiently stiff strip (at least as long as the profile width) on top of the blade (discharge side) at about 50 mm (2 inches) from the blade profile end. Place an inclinometer on top of the straight edge (figure 15).

Figure 15

f. Lift the blade at the tip and rotate the blade around its axis until the desired angle is set, within a maximum tolerance of 0.5 de-grees.

g. Re-check if the blade stem collar is flush against the lower clamping piece. Tighten the U-bolt nuts evenly to full torque as shown in figure 16, starting with the U-bolt at the collar side. Both the torque values of our standard stainless steel (A2) or galvanised steel (ST8.8) hardware as well as our optional A4 stainless steel hardware are shown. The material code A2, St8.8 or A4 is stated on the nut. Make sure that the blade angle does not change during this operation (for the correct thread size refer to table 8 on page 23). After tightening of the nuts, the threaded bolt ends out of the nuts shall have equal length. The U-bolt is damaged if this is not the case and don't fit for purpose anymore.

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Note: the polyester stem will be com-pressed during this operation and may pro-duce a cracking sound.

Figure 16

h. Repeat the above operation for all blades. i. Re-tighten the U-bolts after 50-75 hours in

operation, or 120-150 hours stand still. Do not loosen the nuts first, but start to tighten immediately.

j. When the blade angle has changed, the U-bolts need to be tightened again to full torque and also re-tightened after 120-150 hours.

Minimum tip-clearance

Tip clearance s is the distance between the blade tip and the impeller casing (figure 17). Due to normal impeller casing tolerances the tip clearance is not constant around the im-peller casing.

Figure 17

Howden recommends a tip clearance of 0.5% of the impeller diameter. Fan selections using Howden CF-P20 software use this default stan-dard, unless otherwise specified. Tip clearance shall never be less than 0.25%.

WARNING DO NOT forget to re-tighten the U-

bolts as they may loosen due to creep of the FRP material of the blade stem.

ONLY use original Howden hardware. The nuts are treated with special low friction coating.

DO NOT re-tighten location bolts of the lower clamping pieces (location bolts are used in special applications only).

After loosening and disassembling of a U-bolt, the legs of the U-bolt have lost the parallel shape due to relaxation effects. That is why it is not allowed to re-use those U-bolts.

Thread size M12 M16 M20 M24 M30 M36 M42

(A2, St8.8) = Standard Nm lb.ft 60 44 140 103 250 184 425 313 650 479 1100 811 1300 959

( A4) = Optional Nm lb.ft Idem 380 280 500 369 970 715 - -

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To make sure that the tip clearance is not less than 0.25% in any location we recommend the following steps: a. Determine the longest blade by measuring

the tip-clearance of all blades at a fixed point in the fan casing.

b. Now measure the tip clearance of the long-est blade at a number of measuring points (see table 4 for the number of recom-mended measuring points). Slowly rotate the impeller by hand to the different meas-uring points.

c. Centre the impeller in the casing, or the casing around the impeller, in case the tip clearance is too small and repeat the previ-ous steps.

Diameter

Metric (mm) Diameter

Imperial (ft.) Number of meas-uring points

700-2000 3-6 4 2001-4000 7-13 6 4001-6000 14-18 8 6001-12500 22-40 12 12501-16000 44-48 16 Table 4

Impeller diameter reduction In case the tip clearance is smaller than the above described minimum tip clearance, and centring the impeller does not help, one has the possibility to reduce the impeller diameter by placing one or more 5 mm thick nylon spacer rings between the blade stem collars and the lower clamping pieces. The same number of spacer rings shall be installed on all blades of an assembly. This method allows the impeller diameter to be reduced by 40-50 mm. After installing the nylon rings, torque the nuts again according to the blade installation proce-dure as described previously.

Retaining plate

(Supply of retaining plate is optional).

Install retaining plate with gasket, washers and bolts after the coupling flange or after the im-peller has been installed. For torque values of electro-galvanised retaining plate bolts see table 7 on page 22 of this manual.

Important

Howden strongly recommends the installation of a retaining plate for all vertical shaft applications with impeller hanging below the driver or whenever the airflow is directed towards the driver.

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Balancing The impellers are balanced according to ISO 1940, balancing quality grade G6,3. Impellers with a diameter smaller than 4455 mm or 14 feet are balanced in assembly ac-cording to a certain hub-plate configuration: A. Clamping pieces installed at flow inlet side B. Clamping pieces installed at flow outlet side A sticker on the hub-plate marks the applied balancing method. See figure 18.

Figure 18 Sticker as attached on the hub-plate

If not agreed otherwise, the impeller is bal-anced according method B by default.

IV. COMMISSIONING a. Check all bolts and nuts for proper tighten-

ing (including the fan casing hardware). b. Make sure that the metal bearing support

structure is electrically earthed in order to avoid sparkling by electrical static dis-charge.

c. Turn the impeller by hand to check that it runs freely and does not rub or strike the impeller housing.

d. Impellers driven by a two-speed e-motor: Only switch from high speed to low speed after the impeller speed has slowed down to less than the low speed. To be sure you may choose to switch the e-motor only after the impeller has come to a complete standstill. Neglecting this rule may lead to irreparable impeller damage!

e. Make sure that all tools and assembly aids like beams, supports, laddersetc. have been removed. All the required protec-tions, mechanical and electrical must be installed before starting the fan. Make sure that all applicable local safety require-ments have been met to ensure safe op-erating conditions.

f. Bump the motor to check for clockwise rotation of the impeller, when viewed into the air stream (also see figure 6).

Important

If the impeller is installed in a different hub-plate configuration than it was balanced, e.g. configuration B for an installation with the clamping pieces at flow inlet side, you run the risk of an unquiet operation.

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g. Immediately after first start up check for smooth operation of the fan assembly. Check for irregular noise / vibrations. Howden adopts the guideline given in standard ISO-14694 describing the acceptable vibration levels. The in situ vibration level of any fan is not solely dependent on the balancing grade. Installation factors, the mass and stiffness of the supporting system, will influence the in situ vibration level. Therefore, fan vibration level in situ is not the responsibility of the fan manufacturer unless specified in the purchase contract.

ISO-14694 classifies fans according to their application and drive power. Howden cooling fans are in general used for industrial processes, power generation and HVAC with a drive power level up to 300 kW. According ISO-14694 Howden cooling fans are classified in the so-called fan application category BV-3. For fans in application category BV-3 balancing grade G6.3 is recommended (ISO-14694) and therefore Howden cooling fans are balanced according to this balancing grade. The vibration levels given in table X are a guideline for acceptable operation of Howden cooling fans. Immediately after commissioning the vibration level has to be below or at the given start-up value. When the vibration level increases to alarm level investigation to the cause of this level has to be initiated and action taken to correct it. When the vibration level increases to shutdown level corrective action should be taken immediately or the fan should be shut down. The vibration limits shown in table X apply to assembled fan units. The values shown are velocity, in millimetres per second (mm/s). Filter-In, at fan rotational frequency and are to be taken at the fan bearings or at gearbox sides as per figure

19, in case the fan is mounted directly on the gearbox shaft.

Figure 19 Vibration Measuring Points measured at Fan

Units of Air Cooled Condensers

Possible Measuring Points

1 Gearbox - lateral flange - horizontal

2 Gearbox - front end - horizontal

3 Gearbox - bearing cover of output shaft - vertical

2

3

1

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h. Measure the power. In case the fan power (after correction for temperature) is different than required, adjust the pitch angle accordingly (3 degrees tolerance from de-sign blade angle). Note: the absorbed power is inversely proportional to the air temperature. If a larger adjustment is re-quired, after temperature correction, verify with a new fan selection or contact Howden.

i. Re-tighten the U-bolts after 50-75 hours in

operation, or 120-150 hours stand still. Check the tightening torque of the bolts of the tapered bushing and the coupling flange bolts.

V. PREVENTIVE MAINTENANCE Though the impeller requires little maintenance, it is recommended to conduct inspections at regular intervals, to check damage due to vibrations, fouling or wear and tear. Actual recommended maintenance intervals will depend on the use and operation of the complete system and shall be determined by the operator. Check for smooth operation of the fan

and listen for irregular noise or vibrations. De-energise the fan and make a visual

inspection for deposits, and or damages. Visually inspect the blades surface and

blade stems for cracks. Hairline cracks could appear in resin rich areas around the edges of the fan blade and will nor-mally stop progressing. Hairline cracks in itself are harmless, however we advise you to fill these cracks with a touch-up material (PU filler, e.g. Sikaflex 252) to prevent moisture penetration affecting the blades. Howden Cooling Fans can provide you a repair kit complete with in-structions. For all other cracks we suggest to send photographs to Howden Cooling Fans for evaluation.

Important

De-energise the fan and use lock out and tag out procedures prior to performing adjustments, service, inspections or lubrication.

WARNING Contact with rotating fan blades can cause severe injury or death. Never insert items into the fan to determine movement or direction of rotation. Install fan guards or screens on arrangements with exposed fans. Always use lockout and tag out procedures before performing fan adjustments, maintenance, service or inspection.

Important

Following measures must be emphatically respected for potentially explosive environments and to comply with Directive 94/9/EC (ATEX 100):

Electrically earthed metal bearing support to avoid sparkling by electrical static discharge

Minimum prescribed tip clearance to avoid rubbing along the impeller casing.

Directions for design of the impeller support structure according to Howden document 03-07.341

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Visually inspect the blades for wear and tear. Exposed fibreglass should be re-coated. We recommend shipping the worn blades to Howden for refurbish-ment.

For wet cooling tower applications visu-ally inspect if the leading edge protection is still sufficient. If the leading edge pro-tection is (partly) worn, we advise to ei-ther install Howden stainless steel nose caps or to apply a new PU coating. The stainless steel caps can easily be in-stalled over the leading edge of the blades and attached with rivets is a practical solution for repair inside a cool-ing tower. Howden shall be glad to ad-vise you the best maintenance solution for your application.

Replace corroded bolts and nuts. Deposits should be removed from impel-

ler and fan housing using brushes and/or a water jet with a maximum water pres-sure of 3 bar or 45 psi. This is even more important after change out of any blades, to ensure proper balance.

Check if the drainage holes at the blade tip and blade shoulder are still open.

Repairs of the FRP blades shall be carried out strictly in accordance with Howden pro-cedures. We suggest that any damage be photo-graphed and forwarded to Howden Cooling Fans for evaluation.

VI. CONTACT HOWDEN

Howden Cooling Fans Lansinkesweg 4 P.O. Box 975 7550 AZ Hengelo The Netherlands Tel. +31 74 255 6000 Fax +31 74 255 6120 Email: [email protected] Web: www.howdencoolingfans.com

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VII. TROUBLE SHOOTING In case of any failure, please contact Howden stating the impeller order number as mentioned on the nameplate located at the hub of the impeller.

Problem Possible cause Possible solution Air volume low. Fouling of system. Clean system air-cooler

bundles or cooling tower fill.

Obstacles in housing/air stream.

Check actual total area of obstacles and impeller housing inlet shape against original selection.

In dry-coolers the mini-mum required free height of the air inlet area is 1.0 times the fan diameter. This shall be higher in case of multiple row units.

Static pressure higher than specified.

Increase blade angle. (Up to 3 degrees, thereaf-ter do selection check).

Blade angle decreased due to rotation of the blades. (I.e. forgot to re-torque the U-bolt nuts).

Re-set blade angle and refer to the blade installa-tion instructions for the correct torque.

Air temperature higher than design air tempera-ture.

Increase blade angle. (Up to 3 degrees, thereaf-ter do selection check).

Power absorption (too) high. (1)

Fouling of system. Clean system air-cooler bundles or cooling tower fill.

Obstacles in housing/air stream.

Check actual total area of obstacles and impeller housing inlet shape against original selection. In dry-coolers the mini-mum required free height of the air inlet area is 1.0 times the fan diameter. This shall be higher in case of multiple row units.

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Problem Possible cause Possible solution Power absorption (too) high. (2)

Static pressure higher than specified.

Decrease blade angle.

Clean system air-cooler bundles or cooling tower fill.

Air temperature lower than design air temperature.

Check performance against current air tem-perature.

Airflow too high. Decrease blade angle. Blade angle too large. Set blade angle according

fan selection details. Transmission out of order. Check transmission.

Impeller is rubbing against fan casing.

Bolting of drive-train con-nection, support structure or fan housing is not tight.

Tighten all bolts.

Impeller not centred. Centre the impeller. Tip clearance too small. Decrease impeller diame-

ter by placing nylon rings between lower clamping pieces and blade stem collars.

Fan casing too weak. Stiffen fan casing. Vibration level high. (1) Imbalance of impeller. Check if position of fan

blades is according to in-struction.

Lack of stiffness in support structure.

Reinforce support struc-ture.

Bolting of drive-train con-nection or fan housing is not tight.

Tighten all bolts.

Drive alignment incorrect. Realign. Driver bearing damage. Repair or replace. Drainage holes are

blocked. Open the drainage holes.

Blade is not flush against lower clamping piece.

Release U-bolts, pull the blade outwards and re-tighten the U-bolts to the correct torque.

Blade angle(s) not within 0.5 tolerance.

Re-set the blade angles.

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Problem Possible cause Possible solution Vibration level high. (2) Blades are out of tracking.

The blade tips should be reasonably located in the same plane. A maximum tolerable deviation of 0.5% of the fan diameter is ad-vised.

Contact Howden for ad-vise.

Fan is in stall. Decrease blade angle or replace impeller.

Resonance of the cooler structure.

Change natural frequency of the cooler or run the fan at a different speed or install a fan with more or fewer blades.

Scratches or small dam-ages.

Transport and handling. We advise to fill these cracks with a touch-up material e.g. Sikaflex 252 to prevent moisture pene-tration affecting the blades (Contact Howden for a re-pair kit).

Hairline cracks on blade surface.

Could appear in resin rich areas around the edges of the fan blades and will normally stop progressing.

Hairline cracks are harm-less in itself, however we advise to fill these cracks with a touch-up material e.g. Sikaflex 252 to pre-vent moisture penetration affecting the blades (Con-tact Howden for a repair kit).

Noise higher than pre-dicted.

Airflow higher than speci-fied.

Reduce blade angle.

Static pressure too high. Fan too close to obstacles. Contact Howden for ad-

vise. Influence of mechanical

noise caused by drive-train.

Contact drive-train sup-plier.

Resonance of fan-drive and/or support structure.

Contact Howden for ad-vise.

Table 5

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VIII. OVERVIEW TIGHTENING TORQUES Torque values for impeller hardware

Class 8.8 (A3B) A2, St8 A4 Application Bolts size Nm lb.ft Nm lb.ft Nm lb.ft

Tapered bushing

5/16 (P2) 22 16 3/8 (Q2, R2) 39 29 1/2 (S1) 95 70 5/8 (U1) 190 140 3/4 (W1, W2) 339 250

Coupling flange bolts*

M12 75 55 75 55 M16 185 136 185 136 M20 360 266 360 266 M24 625 461 625 461 M30 1260 929 1260 929 M42 2600 1918 2600 1918 M48 5500 4057 5500 4057

U-bolts*

M12 60 44 60 44 M16 140 103 140 103 M20 250 184 250 184 M24 425 313 380 280 M30 650 479 500 369 M36 1100 811 970 715 M42 1300 959 - -

Table 6

*(See hardware overview table 8 on page 23 for correct bolt size) Torque values for retaining plate bolt Class 8.8 / A4 Retaining plate [mm] / [inch]

Thread Size

Nm lb.ft

79 mm / 3.11

M10 48 35 M12 85 63 M16 150 110 M20 195 144

189 mm / 7.44 M16 200 148 M20 245 181 M24 300 221

240 mm / 9.45 M24 540 398 M30 700 516 360 mm / 14.17 M30 850 627

Table 7

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IX. HARDWARE OVERVIEW Dia Met.

(mm) Dia Imp.

(ft) Thread size U-bolt Coupling

type Thread size

coupling bolts ENF ELF ELFA 1219 4

M12

80 M12 1240 1385 1524 5 1585 1780

115 M16

1829 6 1980 2134 7 2220 2438 8 2475 2743 9

190 M20

2775 3048 10 3120 3353 11 3515 3658 12

M16 3962 13 4267 14 4455 4877 16

M20

250 M24

4950 5486 18 5545 6096 20

M24 6240 6702 22 7030 7315 24 7920

M30 335 M30

7925 26 8535 28 8910 9145 30 9754 32 9900 10000 10400 34 10973 36

M36 M42 500 M42 11100 12192 40 12400 Table 8

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X. GUIDELINE FOR ACCEPTABLE VIBRATION LEVELS OF COOLING FANS IN APPLICATION CATEGORY BV-3 (ACCORDING ISO 14694)

CONDITION

RIGIDLY MOUNTED (1)

FLEXIBLY MOUNTED (2)

PEAK [MM/S]

R.M.S. [MM/S]

PEAK [MM/S]

R.M.S. [MM/S]

START-UP 6.4 4.5 8.8 6.3

ALARM 10.2 7.1 16.5 11.8

SHUTDOWN 12.7 9.0 17.8 12.5 * Rigidly mounted: Structure of concrete ** Flexibly mounted: Structure of steel, wood or composite Table 10 XI. DOCUMENT VERSION CONTROL Version 04 December 1, 2010 Removed mild before steel hub in description, p3.

Changed allowable operating temperature in table 1 :

Max. + 65C + 149F

Inserted section: De-commissioning

Vibration measurement procedure changed in g. of chapter: IV. Commissioning Inserted Possible to heading Measuring Points p15.

Added a new chapter: IX. Maximum Vibration Levels For Balance Vibration category BV-3 (ISO 14694) & added Table 9

Changed material codes:

Old New AISI 304 A2 AISI 316 A4

Inserted Blades Installation Procedure b, p13 Inserted IV Commisioning Section G p17

Installation and MaintenanceWarningAllowable operating temperatureIntroductionAllowable incidental upset temp. (

service manual e-series cofimco

Documents

blades installation

service manual howden

flow direction

field service

coupling flange

hubplate installation

handling storage disposal

general information