Exhaust Fans
Fans shall be of the type, size, arrangement and capacity as indicated in the schedule and/or as shown on the drawings.Unless specify, fans performance rating data shall be tested accordance with AMCA Standard 210-85 (Air Moving and Conditioning Association), ANSI/ASHRAE Standard 51-1985 “Laboratory Methods of Testing Fans for Rating”. Sound ratings shall conform to AMCA Standard 300-85, “Reverberant Room Method for Sound Testing of Fans”.
A computer printout of fan performance rating corresponding to the AMCA licensed data, with corrected ratings for altitude and temperature, fan operating speed, bearing life, etc. shall be submitted for approval.
All fans shall be dynamically trim-balanced to ISO1940 and AMCA 204/3 – G 2.5 quality grade after assembly. A computer printout with the vibration spectrum analysis not less than 12000 CPM (200 Hz) shall be attached to the fans.
Fan motors shall comply in all respects with continuous rating in accordance with IEC34 or equivalent. Motor bearings shall be of ball or roller type, grease or lubricant sealed for life. Fan and drive shall be earthed to prevent accumulation of static charge.
Kitchen exhaust fan shall be of Bifurcated Axial or SISW Centrifugal direct or belt driven type. Double Inlet Double Width (DIDW) Centrifugal and Direct Drive Axial Flow Fan where belts or motor are in the air stream are not acceptable.
Fans shall be installed at staircase or lobby where fresh air intake is free from any obstruction and shall be energized only by fire alarm system. Fan shall be of Axial Flow Fan or DIDW Centrifugal Fan. Protective grille at the suction of the fan is required.
Fans for elevated temperature (Smoke Extraction Fans) with components rated for high temperature (250 deg C, 2Hrs) service, with belt drive assemblies exposed to the air stream are not acceptable.
For Smoke Extraction Fans where motor is in the air stream with electrical/electronic temperature limit switch for motor protecting shall not be used.
Anti-condensation heater is recommended to be installed for all Pressurization and Smoke Spill Fans, and the control circuit shall be arranged such the way that the heater is off when the starter is on and vice versa. Heaters shall be wired from the respective local motor control panel or motor control console.
Quality Assurance
All fans shall posses “AMCA Seal” or equivalent on Air and Sound Performance where specified.Install fans, with their accessories, to comply with state and local Codes (Govt. Fire Department) and UBBL (Uniform Building By-Laws) 1984.
The manufacturer shall be certified with ISO 9002 Management System for manufacturing and assembly of ventilation equipment as a minimum quality assurance requirement.
Technical Submittals
Submit manufacturer’s latest published data for dimensions, materials, accessories and installation details.
Submit full technical rating data based on tests in accordance with current AMCA standards. Include independent body certified fan performance curves, and certified sound power ratings. (Submit certified test certificate to substantiate performance). Correct all ratings and curves for altitude and temperature where applicable.
Fan static pressure calculation based on the system to be installed.
Certified sound power ratings for different octave band.
ISO Certificate
Fire Certificate for Smoke spill Fan
Sound spectrum calculation sheet on specified N.C. level
Types of Fans
Axial Flow Fans
Direct drive fans shall be licensed to bear the AMCA Air and Sound Certified Ratings Seal. The test standard used shall be ANSI/AMCA 210-85, ANSI/ASHRAE Standard 51-1985 “Laboratory Method of Testing Fans for Rating” and AMCA 300 “Reverberant Room Method for Sound Testing of fans”.Fans shall be oven-baked with polyester coating for minimum thickness of 60 microns or hot-dipped galvanized. To achieve the minimum and equal clearance between the blade tips and casing, tube casing shall maintain its roundness by means of using one piece of sheet metal with 90 deg edge flanging up.
Fan motor base support shall be properly secured (locked and sealed) to the fan housing and be of adjustable type to have precise control of motor shaft central position as well as running clearance between blade tips and casing. Motor (KW/HP) shall be able to be changed or upgraded at site without changing fan housing or ducting construction.
Fans supplied shall be complete with factory fabricated mounting bracket (ceiling or foot mounted) and suction/discharge matching flanges as accessories.
All hubs shall be cast Aluminium alloy (Grade LM2) unless for Smoke Extractor Fans where high temperature (250°C/2Hrs) air is expected then Aluminum alloy or steel fan impeller blades are required. Otherwise impeller blade material with Polypropylene (PP), Glass-reinforced Polypropylene (PPG) and Glass-reinforced Polyamid (PAG), to provide self-balancing, anti-static, anti-sparking characteristic is preferable.
Running clearance between blade tips and casing shall not exceed 1% of the impeller diameter, and 2% for smoke spill high temperature fan where mechanical expansion coefficient is different from normal ambient temperature. Fan manufacturer shall provide the fan assembled with the dame clearance between blade tips and casing of the tested prototype. Note that the air performance and pressure loss are greatly affected by this clearance.
Impellers shall be secured to the drive shaft by a key and keyway. Axial location shall be provided by a collar or shoulder on the drive shaft together with a retaining washer and screw fitted into a tapped hole at the end of the shaft and locked in position. Blades shall be secured in place to the angle setting by setscrews, locking nuts or setting pins.
Fan motor shall be totally enclosed and external terminal box of at least IP55 shall be provided.
Fans shall not exceed 1500 RPM.
All fans after assembly shall be dynamically trim-balanced to ISO1940 and AMCA 204/3 – G 2.5 quality grade. A computer printout with vibration spectrum analysis not less than 12000 CPM (200 Hz) shall be attached to the fans.
Smoke Extraction Fan
Smoke and heat exhaust fans are required to be in compliance with the requirements of Class B performance, as defined in clause 9 of BS 7346:Part 2:1990. This requires the fan to be subjected to a rated temperature of 250C for a rated duration of 120 minutes.The fan is required to satisfy the performance criteria specified in BS 7346: Part 2:1990 relating to structural performance, electrical performance and aerodynamic performance throughout the rated duration.
The testing certificate or test report shall be issued by Warrington Fire Research Centre Ltd in U.K. or approval equivalent test laboratory. Contractor shall submit test certificate and full test report from fire testing laboratory and Fire Department approval letter. Smoke and heat exhaust fan without approval by Govt. Department of Fire is not accepted.
For two-stage counter-rotating Smoke Spill Fan for high-pressure application, each impeller shall be driven by a separate motor within a separate casing.
Pressurization Fans
The materials of the fan housing, blades, bearings etc. shall be made of materials to ensure that it can operate continuously for 2 hours in an ambient temperature of 250°C. The fans is required to comply with the requirements for a Class B performance as defined in Clause 9 of BS 7346 PART 2:1990. Contractor shall submit test certificate and full test report from independent fire testing laboratory and Govt. Fire Department approval letter.Test certificate or test report shall be issued by Warrington Fire Research Centre Ltd in U.K. or approval equivalent test laboratory. Contractor shall submit test certificate and full test report from fire testing laboratory and Govt. Fire Department approval letter.
The motor shall be of the totally enclosed squirrel cage induction type fitted with ball bearings of generous size. The insulation shall be Class H.
The Contractor shall supply and install the smoke spill and pressurization fan control and indicator panel at the main fire control room. The fan control and indicator panel shall consist of manual stop/start buttons and fan run/trip indicator lamps for all the fans. All wiring from the main control room at ground floor to the fans shall be Fire rated cable. These status and indication shall be monitored by the BCS.
Bifurcated Fan
Axial Bifurcated fan shall have the motor isolated from the airstream. The fans shall have a built in central chamber ventilated to the external ambient containing the direct drive motor. The hub shall be specially cast in one piece to suit the required distance between impeller and motor shaft. Fan casing shall be carefully controlled to ensure smooth flow of the air to avoid turbulent airflow and noise.Belt Driven Fans
Fan impellers shall be driven by V-belts with the pulley keyed to the shaft and retained by taper-bushes.Motor mounting plate shall be supported using four threaded rods for belt tensioning. Belt tunnel shall be sealed from the air stream and belt guards with proper ventilation should be provided.
Roof Exhaust Fan (Direct Driven)
Fan casing shall be fixed onto the support square base by means of bolts and nuts and properly sealed against air leakage and entry of rainwater.Fan housing and support square base shall be constructed of electro-galvanized or cold roll steel sheet, oven-baked polyester coating or hot dipped galvanized. Weather cowl shall be moulded to cover and overlap the entire fan casing in flame retardant glass fibre reinforced resin.
Support square base and weather cowl overlapping should be designed to ensure smooth flow of the air entry and discharge as tested prototype, otherwise additional pressure loss to the system resistance is required.
Fans shall be suitable for flat or/and pitched roof installation. For fans for smoke extractor purpose, the motor and fan assembly shall be capable of withstanding for 250 deg C for 120 minutes or 300 deg C for 30 minutes.
Axial-Cabinet Fan (Direct Drive)
Fan contained within cabinet shall be licensed to bear the AMCA Air and Sound Certified Rating Seal.Cabinet shall be constructed of galvanized steel material; and shall be of “Panel Construction” assembled together by means of fasteners for easy dismantling for services and maintenance. Welded cabinets are not acceptable.
Cabinet design shall be double skin arrangement (i.e. with internal lining of acoustic media insulation and then covered with pre-galvanized perforated sheet steel for breakout noise reduction).
Fans shall be coupled with vibration spring isolator and vibration-damper couplings within the cabinet to avoid the transmission of noise and vibration to canalization systems.
Sound attenuators, if required, shall be easily installed at the cabinet Air-Inlet and Discharge directly.
For smoke extraction application, the motor and fan assembly shall be capable of withstanding for 250 deg C for 120 minutes or 300 deg C for 30 minutes.
Centrifugal Fans
Fans, forward or backward curved, SISW or DIDW, shall be licensed to bear the AMCA Air and Sound Certified Ratings Seal. The test standard used shall be ANSI/AMCA 210-85, ANSI/ASHRAE Standard 51-1985 “Laboratory Method of Testing Fans for Rating” and AMCA 300 “Reverberant Room Method for Sound Testing of fans”.All fans shall be dynamically trim-balanced to ISO1940 and AMCA 204/3 – G 2.5 quality grade after assembly. A computer printout with vibration spectrum analysis not less than 12000 CPM (200 Hz) shall be attached to the fans.
All fans with total static pressure not exceeding 800 Pascal, fan shall be Forward curved blade type. For total static pressure of 800 Pascal and higher, fan shall be Aerofoil blade type.
Fans shall be oven-baked with polyester coating for minimum thickness of 60 microns, unless the housing scroll and side frame is constructed from galvanized steel sheet (G.I.), Stainless Steel, Aluminium and etc.
Fans housing shall be of an appropriate thickness to prevent vibration and drumming. The fan scroll shall be attached to the side plate by means of continuous lock seam or intermittent spot welding. The wheel and inlet cone shall be aerodynamically designed and constructed to provide maximum performance and efficiency as published by the manufacturer.
Fans must be physically capable of operating safely at every point of rating at or below the “minimum performance” limit for that class as defined in AMCA standard 99-2408-69 “Performance Class of Operating Limits for Centrifugal Fans”.
Shafts sizes shall be carefully calculated and designed such that the maximum operating speed RPM) shall not exceed 75% of the first critical speed. For any application that is not a standard product from catalogue of the fan manufacturer detailed calculation of critical speed characteristic shall be submitted for approval.
Shafts shall be made of carbon steel (C45) machined and polished to tolerance of standard SO 286-2 - grade G6. Protective coat of anti-rusting shall be applied to all bare surfaces of the shafts at the factory.
Bearings shall be of self-alignment (concentric) type with adaptor sleeve bearing. Bearings of eccentric locking collar with grub screw type are not acceptable. Bearing shall be maintenance free with permanently lubricated sealed ball bearing type. Bearing life shall be at least 75,000 hours based on basic rating life, L10 of ISO 281 standard. Calculation sheet of Bearing Life shall be submitted for approval.
Motor installed shall be of a minimum 130% of the fan power absorbed BHP (Brake Horse Power) and shall have sufficient torque available for starting and continuous operation.
Belts and pulleys shall be sized for a minimum 150% of the installed motor horsepower. The belt speed shall not exceed 30m/s. The pulley shall be of Taper Lock SPZ, SPA, SPB or SPC type. Conventional type of pulley is not acceptable. Both fan and motor pulley shall be balanced to the quality grade G 2.5
Fan outlet velocity shall not exceed 10% of the main duct air velocity designed (0.1” per 100 ft or 1 Pascal per meter duct length). Pressure Loss is as referred to in SMACNA Standard, unless otherwise specified.
A computer printout on fan performance rating corresponding to the AMCA licensed data, with corrected rating for altitude and temperature, fan operating speed, bearing life, etc. shall be submitted for approval.
Inlet Guide Vanes
Inlet vane control for modulation of fan where specified for VAV System shall be supplied by the fans manufacturer.Fans capacity shall be as per catalogue performance with the inlet vane fully open and capacity shall be able to be reduced to 25% with maximum closed inlet vane.
Fan shall be backward curved and will not surge for the whole operating range of the desired volume / system resistance. An inspection door is required.
Smoke Extract Fan
C for a rated duration of 120 minutes.°The centrifugal smoke extract fan is required to be in compliance with the requirements of Class B performance as defined in clause 9 of BS7346 PART 2:1990 which require the fan to be subjected to a rated air temperature of 250°C.Fans shall be Single Inlet Single Width (SISW) backward curved type with fan wheel overhung by two bearings with the drive system totally out of the air stream.
Test certificate or test report shall be issued by Warrington Fire Research Centre Ltd in U.K. or approval equivalent test laboratory. Contractor shall submit test certificate and full test report from fire testing laboratory and Govt. Fire Department approval letter.
Smoke and heat exhaust fan without approval by Govt. Fire Department is not accepted.
Centrifugal Roof Smoke Extractor Fans shall be backward curved impeller with vertical air discharge type. Support casing and mounting base shall be in galvanized steel with protection grille/bird net. Weather cowl and weathering skirt shall be molded in flame retardant glass fiber reinforced resin.
Pressurization Fans
The materials of the fan housing, blades, bearings etc. shall be made of materials to ensure that it can operate continuously for 2 hours in an ambient temperature of 250°C. The fans is required to comply with the requirements for a Class B performance as defined in Clause 9 of BS7346 PART 2:1990. Contractor shall submit test certificate and full test report from independent fire testing laboratory and Govt. Fire Department approval letter.Test certificate or test report shall be issued by Warrington Fire Research Centre Ltd in U.K. or approval equivalent test laboratory. Contractor shall submit test certificate and full test report from fire testing laboratory and Govt. Fire Department approval letter.
The motor shall be of the totally enclosed squirrel cage induction type fitted with ball bearings of generous size. The insulation shall be Class H.
The Contractor shall supply and install the smoke spill and pressurization fan control and indicator panel at the main fire control room. The fan control and indicator panel shall consist of manual stop/start buttons and fan run/trip indicator lamps for all the fans. All wiring from the main control room at ground floor to the fans shall be Fire rated cable. These status and indication shall be monitored by the BCS.
Cabinet Fan
Fan contained within cabinet shall be licensed to bear the AMCA Air and Sound Certified Rating Seal. Fan shall be of DIDW Forward or backward curved with fan scroll, belt drive assembled within a cabinet.Cabinet shall be constructed of Galvanized Steel material.
Cabinet shall be of “Panel Construction”; assembled together by means of fasteners for easy of dismantling for service and maintenance. Welded cabinets are not acceptable.
Cabinet design shall be capable of adding acoustic insulation (i.e. double skin arrangement) if requested for noise reduction.
Direct Drive Type
Fans shall be of DIDW Forward Curved centrifugal type with fan scroll within a cabinet.Fan speed shall not exceed 1350 RPM.
Motor shall be for power supply 220 - 240V/50Hz/Single Phase.
In-Line Centrifugal Duct Fan
Fan shall be of SISW, forward or backward curved centrifugal, direct driven type.Casing shall be of Galvanized steel with Oven-baked epoxy coating. Impeller material shall be either Galvanized Steel or Glass Reinforced Polypropylene.
Fan speed shall not exceed 1350 RPM.
Motor shall be external rotor type for power supply 220~240V/50Hz/Single Phase.
Propeller Fan
Fans shall be of the ring-mounted type and the blades constructed from heavy gauge metal. An aerodynamically designed bell mouth constructed from heavy gauge metal shall be provided. The fan speed shall not exceed 1400RPM at 50Hz operation.Propeller fans shall be direct driven type, the motor either a single-phase capacitor start-run or a three-phase squirrel cage induction type. The motor shall have inbuilt inherent protection against overloading. Motor with shaded pole or centrifugal switch type is not acceptable.
Bearings shall be maintenance free permanently lubricated type. Fans shall be completed with wire guards. External grilles, fan chambers and volume control damper shall be provided where indicated in the specification drawings.
Chemical Resistance Centrifugal Fan
Fans shall be of SISW Backward Curve Centrifugal direct drive or belt driven type. Fan blower wheel shall be of backward curve with Glass Reinforced Polypropylene (PPG) material.Fan housing shall be of an appropriate thickness to prevent vibration and drumming. The fan housing shall be of fibreglass material.
Fan must be physically capable of operating safely at every point of rating at or below the “minimum performance” limit for that class as defined in AMCA standard 99-2408-69 “Performance Class of Operating Limits for Centrifugal Fans”.
Bearings shall be out of the air stream and of self-alignment (concentric) type with adapter sleeve bearing. Bearing of eccentric locking collar with grub screw type is not acceptable. Bearing shall be maintenance free with permanently lubricated sealed ball bearing type. Bearing life shall be at least 75,000 hours based on basic rating life, L10 of ISO 281 standard. Calculation sheet of bearing life shall be submitted for approval.
Motor installed shall be IP55 protection with Class F insulation.
Belts and pulleys shall be sized for a minimum 150% of the installed motor horsepower. The belt speed shall not exceed 30m/s. The pulley shall be of Taper Lock SPZ, SPA, SPB or SPC type. Conventional type of pulley is not acceptable. Both fan and motor pulley shall be balanced to the quality grade
Fan outlet velocity shall not exceed 10% of the main air velocity designed (0.1” per 100 ft or 1 Pascal per meter duct length). Pressure Loss is as referred to in SMACNA Standard, unless otherwise specified.
All fans shall be dynamically trim-balanced to ISO 1940 and AMCA 204/3-G 2.5 quality grade after assembly. A computer printout with vibration spectrum analysis shall be attached to the fans.