This method statement covers the fan installation including accessories. The procedure defines the method used to ensure the exhaust fan installation has been carried out as per project contract requirements and best practices.
It also gives details of how the mechanical work will be carried out and what health and safety requirements are implemented on the construction project site.
Relevant Codes and Standards
- Contract / Project Specifications
- Approved shop drawings
- DW 142 / 144 and CIBSE 83
- AMCA Standard
- Inspection and Test Plan
- Project Safety Plan
- Project Quality Plan
- Project Logistics Plan
- Job Safety Analysis JSEA
- Local Regulations as applicable
Necessary Tools
Plant / tools and equipment are to include but not limited to:
- Power tools i.e. electric drill
- Spirit Level
- Measuring tape
- Hammer
- Punching tool
- Adjustable wrench
- Torque Wrench
Roles & Responsibilities
Project manager shall be responsible for but not limited to the following important activities:
To ensure that all preparation and application works are carried out according to the contract specification and manufacturer’s data sheet.
Ensure the progressing of work is carried out according to the planned program and as per approved method statements.
To ensure that all the equipment and materials required are available according to the planned construction program.
Coordinate MEP coordinator and Safety officer for all safe and proper execution in accordance with the risk assessment.
To coordinate with the civil engineer to obtain required access in the installation area.
MEP Site Engineers shall be responsible for but not limited to the following important activities:
Arranging manpower and materials and tools to execute the job at site.
Ensuring works are carried out as per approved shop drawings.
Explaining brief methodology of job to be done.
Ensuring safety and welfare of site staff.
Foreman shall be responsible for but not limited to the following important activities:
Ensure the right material for job is available.
Ensure the works are done with current revision and approved shop drawings.
Guide the technicians to carry out the work according to the approved shop drawings.
Health & Safety Officer shall be responsible for but not limited to the following important activities:
Monitor and ensure the health and safety of the site personnel.
Ensuring that all necessary PPE are available on site and with site personnel.
Maintain good housekeeping on site all the time.
Make sure that all the environmental concerns are addressed in time.
Responsible for implementation and assurance of the health safety and environmental requirements as per the approved JSEA.
QA/QC Quality Engineer shall be responsible for but not limited to the following important activities:
Inspecting the materials on site as per approved material submittals, at delivery and prior to installation on site.
Conducting the installation inspections as per approved drawings and approved checklists.
Preparing test forms for testing on site and updating results accomplished.
Issuing inspection request within 24 hrs before the actual inspection date and time.
Responsible for the assurance of quality control procedures, method statement and inspection test plan.
Exhaust Fan Delivery, Handling and Storage
The fan impeller is carefully balanced and centralized in the fan case, it is therefore essential that great care is exercised when handling the unit.
Never pass lifting slings through the impeller, check the weight on the rating plate details before attempting to lift and always use a spreader as shown in figure below.
Also note that care must be taken when handling a unit/ attenuator assembly fitted with flexible connectors as the flexible connector can be distorted or damaged.
The fan should be protected with oil base coatings the bearing must be kept clean, dry and lubricated. The fan rotor must be kept clean, dry and free from corrosive or erosive elements.
Fan rotor should be rotated frequently to circulate lubricants in the fan bearings and to prevent brinelling of the bearings.
Do not store equipment with the vibration isolators installed.
Never store other materials by stacking or piling items on the fan body.
Whether store inside or outside always protect the fan equipment with traps and protect electrical equipment from corrosion.
Always handle the ventilation fan units carefully to avoid damage and distortion.
The units must be lifted by the base only.
Spreaders should be employed and positioned so as to prevent the slings, webbing etc. making contact with the casing.
Correctly position slings to avoid twisting of the unit case and observe the centre of gravity before the final lift is made.
Heavier units will have eyebolts fitted at each lower corner for hoisting.
Upon receipt of materials on site these will have to be inspected by the Storekeeper and Site Engineer or representative, to ensure correctness of materials, materials / equipment are delivered as per the approval material submittals, quantities and quality.
A Material Inspection Request (MIR) shall be issued and all materials must be inspected and verified by the site engineer that they are correct.
Pre Installation Checks
Before commencing the fan installation check that all material, including optional ancillaries are available to complete the installation, the details recorded on the fan side rating plate should also be referred to before handling and installation.
Any damages or deviations should be immediately reported to the seller/supplier/agent quoting the order and product details from the product rating plate.
Rotate the fan impeller by hand to ensure free and smooth rotation and that no transit or handling damage has occurred, observe the direction of flow/direction of rotation arrow and ensure that:
All optional accessories such as support brackets, inlet cones, guards, flexible connectors etc. are available for assembly as part of the fixed ductwork system.
Anti-Vibration mounts isolate the fan only. Attenuators, and/or duct lining, back draught dampers and other ‘significant mass’ accessories should form part of the fixed ductwork after the flexible connection.
Fan Installation Method
The optional support brackets are correctly fitted, at any position around the circumference, but suit the installation plane.
External termination box is accessible to the electrician.
When offering the fan to the ducted system that both inlet and outlet connections are perfectly aligned.
Vertical and Horizontal fan types should be installed level and plumb to avoid motor bearings damage.
Refer to approved shop drawings for details of mechanical and electrical components.
Mounting Brackets
The brackets can be bolted at any position around the circumference of the unit flange.
Holes are provided on the bottom angle of the brackets for fixing to structure or floor.
Matched to fan size for easy fitting to flanges.
Holes provided for anti-vibration fitting.
Refer to project specifications and approved shop drawings for details of equipment to be fixed with vibration isolators.
Matching Bolted Flange (single)
The matching flanges if required on the installation are fixed to the ductwork ends with rivets.
To allow any ductwork or flex to be terminated with a bolted flange. As per manufacturer recommendation.
Flexible Connector (single)
The Flexible connector is supplied as a continuous band of material sized to suit the fan flange diameter it is matched with.
Clamping bands are included to make a secure airtight joint seal.
Care must be taken when installing flexible connections to ensure that duct misalignment is not corrected by the flexible connection.
Both duct misalignment and slack connections cause unnecessary pressure losses in the system.
The flexible connector will not be tensioned or compressed.
Assembling the Clamping Bands
The band end is passed through the screw clamp and folded back on itself to form the fixed clamp.
Band is then passed around the flexible connector and fed into the clamp by turning the captive screw.
Installing the Anti Vibration Mountings
Anti vibration mounts cannot be fitted to a fan unless there are flexible connectors between the fan or fan silencer combination casing and the ducting.
Suspension mounts in particular should be adjusted on the drop rods to carry an equal proportion of the total fan weight when installed, as unevenly adjusted mountings could carry a load greater than the design condition.
Vibration isolators shall be provided between the equipment and structural elements as per the specifications and approved drawing details.
Anti-Back–draught Dampers
Anti-Back-draught damper should be checked for transit damage prior to installation.
Damper blades should be opened and closed to ensure smooth operation.
Note: not suitable for use in a vertical orientation.
Fan Electrical Installation – Motors
The motors have sealed for life ball bearings in units up. Frame sizes 160mm and above are re-greaseable type.
Electrical supply wiring connection is to an externally mounted terminal box on the case exterior.
The box is pre-wired to the motor with heat resisting cable installed inside flexible duct
Connection Details
Check that the voltage full load and starting current on the fan rating label is suitable for the supply.
Units for external use require weatherproof conduit and glands, provide as applicable.
All wiring and connections to be done as per the approved shop drawings and project specifications.
Installation of under slab and floor mounted fans
Mark the location of the vibration mounting pad support.
Make sure the foundation or mounting arrangement and the duct connection are adequately designed in accordance with manufacturer recommendation.
Lift and fix the the exhaust fan, check the proper alignment of the fan with the duct and flexible connector.
Shock absorber “spring” to be installed based on weight and running power.
Interior partitions shall be additionally secured to the outer casing with welded nose clips at both ends of the sound attenuator.
1″ slip flange shall be standard factory finish on both ends.
Make sure that fans are running properly as per required function and condition, after all connection and support are done.
Below diagrams indicate typical correct / incorrect installation for all types of exhaust fans.
Installation of Centrifugal Fans
Avoid sharp duct bends and changes before inlet opening, especially near the outlet opening. Refer below figure for minimum safe distance behind the outlet opening.
Do not install an angle duct piece immediately after the fan outlet opening.
Use a short, straight duct allowing the flow to equalize.
If the inlet opening has been ducted, ensure that you can replace the bearing by removing the flexible connection duct and part of the inlet ducting or that you can move the fan as a unit towards the service space.
Centrifugal fans are to be installed on vibration dampers which are fastened with bolts in the installation holes of the base frame.
The fastening platform must be even and sufficiently sturdy.
When performing an installation, ensure that there are no bending forces or other mechanical tensions affecting the fan.
Electrical Connections
The fan must have an operating switch and a safety switch which can be secured for the duration of the servicing.
Ensure that the motor cable is long enough so that the motor can be moved freely when tensioning the belts.
The cable should be rubber insulated.
Tighten electrical connectors and terminals according to the approved manufacturer’s published torque tightening values.
If manufacturer’s torque values are not indicated, use those specified in UL 486A and UL 486B.
Fitting accessories
The tightness of the flexible connection duct must be adequate and there must be no bends that could choke the air flow.
Check that the flexible connection duct is in alignment with the fan outlet and the ducting.
Before installing the counter flange, fit a gasket to one flange of the flange joints.
After this, assemble the flange joint.
The fan must not be mounted with the shaft vertical.
Installation of Roof Mounted Fans
The units may be mounted at and up to a maximum roof angle of 600. However, the discharge plenum which houses the shutter mechanism must be uppermost and parallel with the roof ridge (This is to ensure correct shutter operation).
The unit must be securely screwed to its curb or upstand to prevent vibration and wind damage. Refer the project specifications and approved shop drawings for seismic / anti vibration instructions.
All duct connections must be airtight to prevent any loss of performance.
Electrical Wiring
In the case where electronic speed control has been supplied, wire the control to the fan unit and also to the mains supply.
The fan will only operate when a mains signal is present at the switched live (SL) terminal.
When the SL signal is switched off the fan will continue to run for a preset period (defined in the approved manufacturer’s literature).
Adjust the overrun.
All mains connections (including SL) must be fed via a local, appropriately rated isolator unless otherwise stated in the approved shop drawings or as instructed in the approved manufacturer’s literature.
Seismic Controls
For vibration control and seismic measures, refer to the technical specification for Mechanical Vibration and Seismic Controls.
The approved shop drawings will indicate the required details of the vibration isolators for the base of the fans.
Inspection Checklist for Exhaust Fan Installation
| Check that relevant MIR & Shop drawing are approved. |
| Rotation of Fan Wheel is correct. |
| Fan Wheel rotates freely. |
| Fan and motor have been fastened securely, all drives have been correctly aligned. |
| Anti-vibration mountings/ roof curbs installed per manufacturer’s written instruction. |
| Leveling of fan set & base have been carried out and is correct. |
| Field supply wiring has been correctly connected. |
| Earthing connections are clean and secured and earthing cables are fitted. |
| Disconnect switch, electrical interlocks and motor starter located correctly. |
| Ensure that disconnect switch is located near the equipment served and in view of the service technician. |
| Fan bearing lubrication checked. |
| Check duct connections and accessories are installed as per approved shop drawings |
| Check connections of Low Current Systems. |
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