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AS/NZS 3666.1:2002
This Joint Australian/New Zealand Standard was prepared by Joint TechnicalCommittee ME-062, Ventilation and Airconditioning. It was approved on behalf of the Council of Standards Australia on 8 March 2002 and on behalf of the Council of Standards New Zealand on 18 April 2002. It was published on 2 May 2002.
The following interests are represented on Committee ME-062:
Air-Conditioning and Refrigeration Equipment Manufacturers Association of AustraliaAustralasian Fire Authorities CouncilAustralian Building Codes BoardAustralian Chamber of Commerce and IndustryAustralian Industry GroupAustralian Institute of Building SurveyorsAustralian Institute of Refrigeration Air Conditioning and HeatingChartered Institution of Building Services Engineers
Department of Contract and Management Services, W.A.FPA AustraliaInstitute of Refrigeration Heating and Air Conditioning Engineers New ZealandInstitute of Engineers AustraliaPlastics and Chemicals Industries AssociationProperty Council of Australia
Additional interests participating in the preparation of this Standard:
Department of Human Services (Vic)Department of Human Services (Tas)Institute of Plant Engineers Australasia
National Health and Medica l Research Council New South Wales Health DepartmentQueensland HealthTelstra Corporation
Keeping Standards up-to-dateStandards are living documents which reflect progress in science, technology andsystems. To maintain their currency, all Standards are periodically reviewed, andnew editions are published. Between editions, amendments may be issued.Standards may also be withdrawn. It is important that readers assure themselvesthey are using a current Standard, which should include any amendments whichmay have been published since the Standard was purchased.Detailed information about joint Australian/Ne w Zealand Standards ca n be found byvisiting the Standards Australia web site at www.standards.com.au or Standards
New Zealand web sit e at www.standards .co.nz and looking up the relevant Standardin the on-line catalogue.Alternatively, both organizations publish an annual printed Catalogue with fulldetails of all current Standards. For more frequent listings or notification of revisions, amendments and withdrawals, Standards Australia and Standards NewZealand offer a number of update options. For information about these services,users should contact their respective national Standards organization.We also welcome suggestions for improvement in our Standards, and especiallyencourage readers to notify us immediately of any apparent inaccuracies or ambiguities. Please address your comments to the Chief Executive of either Standards Australia International or Standards New Zealand at the address shownon the back cover.
This Standard was issued in draft form for comment as DR 00101.AccessedbyGHD P
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AS/NZS 3666.1:2002
Australian/New Zealand Standard
Air-handling and water systems of buildingsMicrobial control
Part 1: Design, installation andcommissioning
Originated as part of AS 36661989.Previous edition AS/NZS 3666.1:1995.Second edition 2002.
COPYRIGHT Standards Australia/Standards New Zealand
All rights are reserved. No part of this work may be reproduced or copied in any form or by anymeans, electronic or mechanical, including photocopying, without the written permission of thepublisher.
Jointly published by Standards Australia International Ltd, GPO Box 5420, Sydney, NSW 2001and Standards New Zealand, Private Bag 2439, Wellington 6020
ISBN 0 7337 4452 2
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PREFACE
This Standard was prepared by the Joint Standards Australia/Standards New ZealandCommittee ME-062, Ventilation and Airconditioning, to supersede AS/NZS 3666.1:1995.
This Standards forms Part 1 of a series of Standards for the microbial control o f air-handling and water systems, as follows:
AS/NZS3666 Air-handling and water systems of buildingsMicrobial control3666.1 Part 1: Design, installation and commissioning3666.2 Part 2: Operation and maintenance3666.3 Part 3: Performance-based maintenance of cooling water systems
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CONTENTS
Page
FOREWORD ................................................................................................................... 4
SECTION 1 SCOPE AND GENERAL1.1 SCOPE......................................................................................................................... 61.2 OBJECTIVE................................................................................................................61.3 APPLICATION ........................................................................................................... 61.4 REFERENCED DOCUMENTS................................................................................... 71.5 DEFINITIONS.............................................................................................................7
SECTION 2 DESIGN, INSTALLATION AND COMMISSIONING OF AIR-HANDLINGSYSTEMS
2.1 GENERAL................................................................................................................. 112.2 AIR INTAKES .......................................................................................................... 112.3 EXHAUST AIR OUTLETS....................................................................................... 112.4 AIR FILTERS............................................................................................................ 122.5 HUMIDIFIERS.......................................................................................................... 122.6 EVAPORATIVE AIR COOLING EQUIPMENT ...................................................... 122.7 COILS........................................................................................................................ 132.8 TRAYS AND SUMPS............................................................................................... 132.9 CONDENSATE AND EQUIPMENT DRAINAGE................................................... 132.10 FAN ASSEMBLIES .................................................................................................. 142.11 DUCTWORK AND COMPONENTS........................................................................ 142.12 TERMINAL UNITS .................................................................................................. 142.13 COMMISSIONING ...................................................................................................14
SECTION 3 DESIGN, INSTALLATION AND COMMISSIONING OF HEATED WATER SYSTEMS
3.1 GENERAL................................................................................................................. 153.2 HOT WATER SYSTEMS.......................................................................................... 153.3 WARM WATER ABLUTION SYSTEMS ................................................................ 153.4 COMMISSIONING ...................................................................................................16
SECTION 4 DESIGN, INSTALLATION AND COMMISSIONING OF COOLINGWATERSYSTEMS
4.1 GENERAL................................................................................................................. 174.2 PUMPS...................................................................................................................... 184.3 LOCATION............................................................................................................... 184.4 DRIFT CONTROL .................................................................................................... 184.5 CONTROL OF SOLIDS............................................................................................184.6 SUNLIGHT ............................................................................................................... 194.7 COMMISSIONING ...................................................................................................19
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FOREWORD
Microbes abound in the natural environment and are normally present in low concentrationlevel throughout buildings. Building systems are not sterile and will always contain somemicrobes. Generally, health hazards, which can lead to infections such as legionnairesdisease or Pontiac fever, or allergic reactions such as humidifier fever, are created onlywhen these microbes multiply to high concentrations.
The three main categories of microbes that can be found in building environment areviruses, fungi and bacteria. Viruses are the simplest form of microorganism (microbe) butthey can only reproduce within other living cells. The sources for viral transmission are theoccupants rather than the building services. On the other hand, fungi and bacteria cancolonize in building services if moisture and organic nutrients are present. Fungi (e.g.mould) attach to hard surfaces and are readily able to grow in conditions of high humidityas they extract their moisture from the air. Fortunately, they are readily controlled by thenormal principles of hygiene, such as keeping surfaces dry, and by regular cleaning anddisinfection with a mild bleaching agent. While fungi are difficult to eliminate, they willgerminate only when moisture returns.
Examples of systems that are only intermittently moist, but which are able to support fungalgrowths, are cooling coils, condensate trays, drain lines, ducting near cooling coils, andhumidifier surfaces.
Bacteria also prefer wet surfaces for growth but are generally to be found where thesurfaces are submerged or at the interface between wet and dry areas.
Colonization and growth of Legionella bacteria (the causative agent for legionnairesdisease), can take place in any water-based system if the water is warm and supplied withnutrients. Examples of such systems relevant to building services are showers and baths,and cooling towers (and the like) used for heat rejection for which control measures aredescribed in this Standard.
Other sources include spa pools, decorative fountains, nebulizers (for hospital patients)ultrasonic humidifiers (misters at supermarket vegetable cabinets), cutting fluid (inindustrial machine shops), dental equipment and, more recently, the potting mixtures andother composted material used by home gardeners.
As Legionella bacteria are widespread in natural water sources, such as rivers, lakes, mudand soil, it is not surprising that they are often present in building water systems. Absoluteexclusion of these particular bacteria from water systems, although a worthy objective, maynot be possible nor necessary, and finding the bacteria does not by itself indicate that a
source presents a risk. AS/NZS 3666.3 provides requirements for system decontaminationshould elevated Legionella counts be found.
One type of application of particular concern is the provision of warm water for bathing or showering at some hospitals and institutions for the elderly, children and the mentally ill.This water is usually supplied at a temperature of 45C maximum, to prevent scalding.Therefore, Legionella control by elevated temperature at the point of use is not possible.Often, a storage-type warm water system is provided rather than a hot-cold mixing system.Cases of legionnaires disease amongst susceptible people have been associated with theaerosol sprayed from showerheads or bath taps supplied by such systems. Adverseconditions can be created by the build-up of sludge in storage vessels and possible deadlegs in the piping system. Regular cleaning, maintenance and disinfection of the system are
required.
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The problem can be largely overcome by the provision of anti-scald, thermal shut-off devices that mix hot and cold water supplied to the shower outlets instead of using warmwater storage tanks or calorifiers. Such outlets can be readily dismantled and disinfected
periodically with chlorine. Alternat ively, cold water , which is directly heated to producewarm water, can be used.
In the case of cooling water systems that make use of cooling towers to evaporatively coolrecirculating water, the risk of disease can be minimized by the following:
(a) Careful attention to system design and construction features.
(b) Use of drift eliminators.
(c) Siting of towers away from building air intakes, populated areas and discharges fromkitchen exhaust systems.
(d) Maintaining the system in a clean and sound condition.
(e) Controlling water quality from when water is introduced into the system.
(f) Monitoring towers and water condition.Similarly, the control of all microbes able to colonize water and air-handling systems of
buildings can be effected by the avoidance of growth needs, by ensuring the systems areclean, properly designed, commissioned, operated and well maintained, and by the use of appropriate water treatment techniques.
Further explanatory information regarding this subject can be found in the StandardsAustralia/Standards New Zealand Handbook HB 32, Control of microbial growth in air-handling and water systems of buildings, and in the monograph produced by the NationalEnvironmental Health Forum entitled, Guidance for the control of Legionella [found at thewebsite www.health.sa.gov.au/pehs (click Publications then Legionella). The AustralianInstitute of Refrigeration Air Conditioning and Heating has produced a series of applicationmanuals on cooling towers, water treatment, piping systems and maintenance.
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STANDARDS AUSTRALIA/STANDARDS NEW ZEALAND
Australian/New Zealand Standard
Air-handling and water systems of buildingsMicrobial control
Part 1: Design, installation and commissioning
S E C T I O N 1 S C O P E A N D G E N E R A L
1.1 SCOPE
This Standard specifies minimum requirements for the design, installation andcommissioning of air-handling and water systems of buildings for the purposes of microbialcontrol. It does not include requirements for refrigerated room airconditioners and non-ducted split systems.
NOT E: Refer to regula tory authori ty for the application of the cri teria to bui ldings.
Requirements specified in this Standard are not intended for the control of the wide rangeof discomfort symptoms that may afflict the occupants of some buildings.
NOT ES: 1 The Standard covers the most common known sources of the diseases associated with
air-handling and water systems of buildings. Other sources, both known and potential, includecooling water systems for refrigeration equipment and air compressors, industrial heatexchangers when opened for cleaning, decorative fountains, spray irrigation systems, andindustrial water-based cutting fluid systems.
2 In the event of an outbreak of legionnaires disease, special action is necessary, which will beadvised by the health authorities.
3 Further information on the control of microbial growth in air-handling and water systems of bui ldings is given in HB 32.
4 HB 61 provides details of the standard specifications in the NATSPEC series.5 Operation and maintenance requirements are given in AS/NZS 3666.2.
1.2 OBJECTIVE
The objective of this Standard is to assist in the control of microorganisms in buildingsystems, particularly those associated with legionnaires disease, Pontiac fever,
hypersensitivity pneumonitis and humidifier fever.
1.3 APPLICATION
This Standard is intended for use by regulatory authorities, building services designers,architects, equipment manufacturers and suppliers, installers, maintenance personnel,managers, owners, and operating staff responsible for designing, installing, commissioning,operating, and maintaining the air-handling and water systems of a building. It givesminimum requirements and shall be read in conjunction with any additionalrecommendations given by suppliers of the equipment and with the requirements of anyrelevant specification or applicable regulation.
NOT E: This Standard has been developed for commercial bui lding services systems. Thetechnical content may be applied by the regulatory authority to other commercial or industrialsystems and to domestic systems incorporating a cooling water system.
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1.4 REFERENCED DOCUMENTS
The following documents are referred to in this Standard:
AS1324 Air fi lters for use in general vent ilat ion and airconditioning1324.2 Part 2: Methods of test
1470 Health and safety at workPrinciples and practices
1657 Fixed platforms, walkways, stairways and laddersDesign, construction andinstallation
1668 The use of mechanical vent ilat ion and air-condit ioning in buildings1668.2 Part 2: Mechanical ventilation for acceptable indoor-air quali ty
1851 Maintenance of fire protection equipment1851.6 Part 6: Management procedures for maintaining the fire and smoke control
features of air-handling systems
2345 Dezincification resistance of copper alloys
2913 Evaporative air-conditioning equipment4180 Drift loss from cooling towersLaboratory measurement4180.1 Part 1: Chloride balance method
4254 Ductwork for air-handling systems in buildings
AS/NZS1892 Portable ladders1892.1 Part 1: Metal
2865 Safe working in a confined space
3500 National plumbing and drainage3500.1.2 Part 1.2: Water supplyAcceptable solutions3500.2.2 Part 2.2: Sanitary Plumbing and DrainageAcceptable solutions3500.4 .2 Part 4.2: Hot water supply systemsAcceptable solut ions
3666 Air-handling and water systems of buildingsMicrobial control3666.2 Part 2: Operation and maintenance
4020 Products for use in contact with drinking water
SAI/SNZHB 32 Control of microbial growth in air-handling and water systems of buildings
HB 61 NATSPECHandbook at building Standards extracts
MP 52 Manual of authorization procedures for plumbing and drainage products
NZS4303 Ventilation for acceptable indoor air quality
NFPA 90A Installation of air conditioning and ventilating systems
ABCB Building Code of Australia
1.5 DEFINITIONS
For the purpose of this Standard, the definitions below apply.
1.5.1 Aerosol
Airborne water particles less than 10 m in diameter.
1.5.2 Air filterA device for removing particulate material from air.
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1.5.3 Air-handling plant
A component part of an air-handling system, which includes equipment providing air movement, as well as equipment for the purpose of controlling the direction, rate of airflow,division of airflow, and condition of air. It includes central station built-up plant, rooftop
plant, package conditioners (freestanding or connected to ductwork), fan coil units,induction units, and process coolers (such as those used for the cooling of computer equipment).
1.5.4 Air-handling system
A system for the purpose of directing air in a positive and controlled manner to and fromspecific enclosures by means of air-handling plant, ducts, plenums, air-distribution devicesand control devices.
1.5.5 Air intake
Any opening through which air is admitted to an air-handling system in a building.
1.5.6 Air outlet
Any opening through which air is delivered by an air-handling system to a space in a building.
1.5.7 Approved and approval
Approved by, or the approval of, the regulatory authority concerned.
1.5.8 Automatically controlled (water treatment)
Dosage regulated by feedback control loop or timer
1.5.9 Biocide
A physical or chemical agent that kills bacteria and other microorganisms.
1.5.10 Bleed-off (or blowdown)
The removal of water from a system to limit the concentration of total dissolved solids andsuspended solids.
1.5.11 Building
Any structure classified in the Building Code of Australia.
1.5.12 Clean
That part of maintenance which has as its objective plant free from visible sludge, foam,slime (including algae and fungi), rust, scale, dirt, dust and any deposit or accumulation of impurities, or any other foreign material.
1.5.13 Coil
A heat exchanger made up of tubing formed into a compact shape by spiral or serpentineconfiguration, and usually incorporating surface fins.
1.5.14 Commissioning
A systematic and progressive process of putting the components of a system into operation,calibrating instruments and controls, and then making adjustments and checks to ensure thatthe total system is providing satisfactory operation and performance.
1.5.15 Competent person
A person who has had appropriate training or practical experience (or both) in the subject,sufficient to provide safe and satisfactory performance.
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1.5.16 Cooling tower
A device for lowering the temperature of water by evaporative cooling in whichatmospheric air is in contact with falling water, thereby exchanging heat. The term alsoincludes those devices that incorporate a water-refrigerant or water-water heat exchanger.
1.5.17 Cooling water systemA heat exchange system comprising a heat-generating plant, a heat-rejection plant andinterconnecting water recirculating pipework and associated pumps, valves and controls.
1.5.18 Corrosion resistant
Material that is not inherently susceptible to rapid corrosion under the conditions normally prevailing in the system.
1.5.19 Dead-leg
A section of the system that does not permit the circulation of water.
1.5.20 Drift
Water lost from the cooling tower as liquid droplets entrained in the exhaust air, excludingcondensation.
NOT E: Drift is not to be confused with plume, i.e . condensed water vapour .
1.5.21 Duct
A component part of an air-handling system intended for the passage of air from one part of an air-handling system to another.
1.5.22 Ductwork
The network of ducts (including plenums), which forms part of the air-handling system of a building.
1.5.23 Evaporative airconditioning equipment
A device that effects a reduction of the dry bulb temperature of air by evaporating water into air.
1.5.24 Evaporative condenser
A heat exchanger in which refrigerant is cooled by a combination of air movement andwater spraying ( see also cooling tower).
1.5.25 Exhaust air outlet
An outlet from an air-handling system, discharging air to atmosphere.
1.5.26 Hot waterWater at or above 60C.
1.5.27 Humidifier
A device for adding moisture to air to raise its humidity. NOT E: Humidi fiers are of severa l types, including steam, spray, atomizing and boi ling water .
1.5.28 Humidifier fever
A form of allergic reaction caused by inhalation of allergens of microbial origin arisingfrom the wetted surface of equipment, such as humidifiers.
1.5.29 Hypersensitivity pneumonitis
Respiratory illness usually caused by inhalation of the spores or antigens of variousdifferent types of microorganisms; also known as extrinsic allergic alveolitis.
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1.5.30 Installation
Mounting plant, equipment and controls, securing in position, connecting up to componentsof a system for subsequent commissioning of the plant and the associated system.
1.5.31 Legionnaires disease
A potentially fatal illness characterized by pneumonia and caused by infection with Legionella bacteria species, commonly Legionella pneumophila . The incubation period of the disease is from 2 to 10 days, and the attack rate is low. Symptoms include an abruptonset of high fever, non-productive cough, chills, headache and muscle pain.
1.5.32 May
Indicates
(a) that a course of action is permissible; and
(b) the existence of an option.
1.5.33 Pontiac fever
A self-limiting, short-duration, non-fatal fever caused by Legionella bacteria. Theincubation period of the disease is from 5 h to 66 h, and the attack rate is up to 95%.Symptoms include chills, headache, muscle pain, and other flu-like symptoms.
1.5.34 Recirculation
The full or partial redistribution to spaces, by air-handling plant, of air previously extractedfrom those spaces.
1.5.35 Regulatory authority
Any authority that is authorized by statute to exercise jurisdiction over matters such as thedesign, materials, installation, commissioning, operation or maintenance of any part of an
air-handling or water system of a building.1.5.36 Shall
Indicates that a statement is mandatory.
1.5.37 Should
Indicates a recommendation.
1.5.38 Terminal unit
An appliance receiving, conditioning and delivering air supplied through a duct system.
1.5.39 Tundish
A fitting into which pipework can discharge with an air gap.
1.5.40 Warm water
Water between 30C and 60C (nominally 43C).
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S E C T I O N 2 D E S I G N , I N S T A L L A T I O N A N DC O M M I S S I O N I N G O F A I R - H A N D L I N G
S Y S T E M S
2.1 GENERAL
2.1.1 Outdoor air
The quantity and quality of outdoor air introduced and the design of air-handling systemsshall be in accordance with the requirements of AS 1668.2 or NZS 4303, as applicable.
2.1.2 Access for maintenance
Easy and safe access for cleaning, inspection and maintenance shall be available to andabout all plant, equipment and components covered in this Section. Relevant requirementsof AS 1470, AS 1657, AS/NZS 1892.1 and AS/NZS 2865 shall be complied with.
2.1.3 Provision for maintenanceProvision shall be made for shutdown, to facilitate regular maintenance.
2.1.4 Building plans
Typical information is required in building plans. NOT E: Building plans should include a site survey and should show the proposed locations for cooling towers, air intakes and exhaust outlets. The site survey information should show detailsof existing cooling towers, air intakes, exhaust outlets and natural ventilation openings of
bui ldings adjacent to o r f acing the proposed new ins tal lation.
2.2 AIR INTAKES
2.2.1 General
Intakes of air-handling systems shall be designed to drain away any rainwater that mayenter. Intakes shall prevent the entry of vermin, birds, rodents, and windblown extraneousmaterial, such as leaves and papers. Intakes shall be constructed of corrosion-resistant,non-porous materials suitable for the application.
NOT E: External lights attrac t insects and should not be placed near air intakes.
2.2.2 Location
Intakes shall be located to avoid the ingress of contaminants from flues, air exhausts,cooling towers, sewer vents, waste containers, and other sources of airborne pollution.Prevailing wind directions, wind effects, multiple roof levels and arrangement of adjacentstructures shall be taken into account in locating air intakes.
NOT E: For fur ther requirements, see AS 1668.2 for the location of air intakes.
2.3 EXHAUST AIR OUTLETS
2.3.1 General
Exhaust air outlets of air-handling systems shall be designed to drain away any rainwater that may enter. Exhaust air outlets shall prevent the entry of vermin, birds, rodents, andwindblown extraneous material, such as leaves and papers. Outlets shall be constructed of corrosion-resistant, non-porous materials suitable for the application.
2.3.2 LocationObjectionable exhaust discharges from air-handling systems shall be located to avoidcross-contamination with air intakes, cooling towers or any openable windows or doors, inthe same building or a nearby building. Prevailing wind directions and wind effects shall betaken into account in locating exhaust air outlets.
NOT E: For fur ther requirements, see AS 1668.2 for the location of exhaust air out lets.AccessedbyGHD P
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2.4 AIR FILTERS
Where installed, air filters shall be selected and located so that access is available for maintenance and the accumulation of moisture does not occur. Filter bypass shall beavoided.
NOT ES: 1 Provision of air filters is strongly recommended to help control microbial populations in air-
handling systems. Filters should have a minimum 20% efficiency when tested with test dust No. 1 and a minimum 85% arrestance when tes ted with test dust No. 4. Tests should be inaccordance with AS 1324.2.
2 Mould or other microbial growth is encouraged when filters become wet.
2.5 HUMIDIFIERS
2.5.1 Location
Humidifiers shall be located so as to
(a) prevent accumulation of airborne debris; and
(b) optimize the mixing of water vapour with air being humidified.
2.5.2 Integration of controls
Arrangement of the control system shall be such that the humidifier cannot operate whenthe air-handling system is switched off.
2.5.3 Precipitation of moisture
Over-humidification shall be avoided in order to prevent precipitation of moisture withinthe ducting.
NOT E: The use of steam is preferred to direct water injection.
2.5.4 Disposal of moistureMoisture from sprays, atomizers or sparge pipes shall be collected and discharged inaccordance with Clauses 2.8 and 2.9. Water stagnation in the humidifier shall be prevented.
Ductwork containing humidifiers shall be graded where precipitation of moisture can occur and drained in accordance with Clauses 2.8 and 2.9.
2.6 EVAPORATIVE AIR COOLING EQUIPMENT
2.6.1 Materials and construction
Evaporative air cooling equipment shall comply with AS 2913 and be fabricated fromcorrosion-resistant materials. All internal corners and edges of sumps shall be constructedto facilitate cleaning. All water supply and drainage systems shall comply withAS/NZS 3500.1.2. and AS/NZS 3500.2.2 and associated products shall be authorized interms of MP 52.
2.6.2 Location
Fixed evaporative air cooling equipment shall be located in accordance with therequirements of Clause 2.2 for air intakes.
2.6.3 Drains
Drainage from evaporative air cooling equipment shall comply with the requirements of Clauses 2.8 and 2.9.
NOT E: Automatic draining of water in sumps is an effect ive method for preventing or reducingmicrobial population multiplication.
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2.7 COILS
2.7.1 General
Heat exchange coils shall be constructed from corrosion-resistant materials suitable for theenvironment. Cooling coil design shall also ensure effective removal of airbornecondensate.
Heat exchange coils shall be constructed to permit removal during routine maintenance of any airborne deposits that may lodge on the coil. Provision shall be made for the inspectionand cleaning of coil faces.
Spray cooling coils shall be fitted with effective spray collectors to help prevent carry-over of any water in the airstream.
The spray collection system shall extend across the airstream, and air by-pass shall be prevented.
NOTE: Spray sys tems require per iodic cleaning.
2.7.2 Disposal of condensate
Condensate from cooling coils shall be collected and discharged in accordance withClauses 2.8 and 2.9.
2.8 TRAYS AND SUMPS
2.8.1 General
Trays or sumps shall be provided for the collection and discharge of condensate and spraywater from cooling coils and of condensate from humidifiers and other components. Traysand sumps shall be accessible for inspection and cleaning, and shall be graded to the outletto prevent pondage.
2.8.2 Materials and construction
Trays and sumps shall be constructed from corrosion-resistant materials. All internalcorners and edges shall be constructed to facilitate cleaning.
NOT E: External surfaces of the trays should be treated i f condensation is likely to occur.
2.8.3 Collection of condensate and water
In cooling coil and humidifier applications, trays and sumps shall extend beyond all sidesand corners of the coil or humidifier (e.g., extend under flanges and control valves) toenable collection of condensate or water under all operating and maintenance conditions.
2.9 CONDENSATE AND EQUIPMENT DRAINAGE
2.9.1 General
Drain lines shall be uniformly and continuously graded downwards to prevent collection of water. The drain lines shall be trapped to seal against airflow. Drain discharges shall belocated close to the equipment being served.
Plant rooms that are air-plenums shall be weather-tight or graded and drained to outside the plenum to discharge, via an effective air break, to a tundish drain connected to the buildingdrain.
NOT ES: 1 Water-seal traps of transparent material enable easy inspection of the seal and assist in the
detection of visible contaminants. The depth of the water seal should exceed the static pressure differential of the air -handl ing plant by at least 1.5 times the sta tic pressuredifferential.
2 Any drain not in continuous use should be either connected to a source of regular discharge or connected to a secondary trap that is combined with a drain having regular discharge.
3 Attention is drawn to the requirements of the relevant authority for water supply anddrainage.
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2.9.2 Discharge
Condensate drain outlets shall discharge outside the air-handling plant via an effectiveair-break in accordance with AS/NZS 3500.2.2 to a tundish drain to enable the flow of condensate to be assessed during inspection. The drainage system shall be trapped and
provided with inspection ports for cleaning and checking of the condensate flow.
2.10 FAN ASSEMBLIES
Where moisture is likely to enter the fan assembly, drainage in accordance with Clauses 2.8and 2.9 shall be provided.
2.11 DUCTWORK AND COMPONENTS
2.11.1 Design and installation
Ductwork and components shall be designed to avoid the ingress and accumulation of moisture. Ductwork, components and insulation, shall be manufactured and installed inaccordance with AS 4254.
Ductwork to be installed in the vicinity of moisture-producing equipment shall beconstructed from corrosion-resistant material and shall not be internally insulated.
Plant rooms that are used as air-plenums shall comply with the requirements of Clauses 2.2and 2.9.1.
2.11.2 Drainage
Where moisture is likely to accumulate (e.g. around cooling coils, air intakes or humidifiers), the ductwork shall be graded and drained in accordance with Clauses 2.8and 2.9.
2.11.3 Access for inspection and cleaning
Access shall be provided in ductwork, air-handling plant, plenums, fan chambers, air distribution devices and in building finishes, to facilitate inspection and cleaning of thoseitems in the vicinity of moisture-producing equipment, such as sprayed cooling coils,humidifiers, evaporative airconditioning equipment and to any other items installed withinthe air-handling system requiring inspection and maintenance. Where applicable, accessshall be provided for inspection and cleaning as required by AS 1851.6 and NFPA 90A.
2.12 TERMINAL UNITS
Where water vapour condenses within the terminal unit and is not re-evaporated by theairflow through the unit, a condensate tray in accordance with Clause 2.8 and drainage
facilities in accordance with Clause 2.9 shall be provided. All components shall have accessfor inspection and cleaning.
2.13 COMMISSIONING
Before being brought into service, all new or modified air-handling systems shall bethoroughly cleaned internally, sealed and balanced by competent personnel. All systemsshall be provided with operating and maintenance manuals in accordance withAS/NZS 3666.2.
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S E C T I O N 3 D E S I G N , I N S T A L L A T I O N A N DC O M M I S S I O N I N G O F H E A T E D W A T E R
S Y S T E M S
3.1 GENERAL
3.1.1 Access for maintenance
Easy and safe access for cleaning, inspection and maintenance shall be available to andabout all plant, equipment and components covered in this Section. Relevant requirementsof AS 1470, AS 1657, AS/NZS 1892.1 and AS/NZS 2865 shall be complied with.
3.1.2 Provision for maintenance
Provision shall be made within the system to facilitate regular maintenance.
3.1.3 Materials
Materials used for components in contact with water intended for ablution purposes shallcomply with AS/NZS 4020. Materials shall not foster microbiological growth or reactadversely with treatment or decontamination chemicals. Materials used shall be corrosionresistant.
3.1.4 Pumps
The pump seal sump and the pump casing shall be fitted with drain outlets and be separatelydrained to discharge in accordance with Clauses 2.8 and 2.9.
3.1.5 Water treatment units
Where water treatment units are installed, they shall be located in a convenient position for
inspection, maintenance and operation.3.1.6 Water storage tanks
Water storage tanks shall comply with AS 3500.1.2 and have provision for inspection,cleaning, rapid drainage, and rapid refilling. To prevent the ingress of foreign matter, tanksshall be provided with close-fitting covers or lids and the overflow and vent lines shall befitted with insect-proof covers. Provision shall be made to avoid heat gain to water incold-water feed and storage tanks.
NOT E: Combined storage tanks for potable water and fir e services should be avoided due tocross-contamination possibilities.
3.1.7 Layout
The water reticulation system shall have a minimum of dead-legs. Dead-legs shall becapable of being flushed during maintenance. Drain valves shall be full way types, tofacilitate effective flushing and drainage of system.
3.2 HOT WATER SYSTEMS
Hot water systems shall comply with AS/NZS 3500.4.2. Storage calorifiers, tanks andcylinders shall be designed and installed so as to prevent stratification of temperature.
NOT E: Considera tion should be given to the use of a recirculat ion system.
3.3 WARM WATER ABLUTION SYSTEMS
Warm water systems shall comply with AS/NZS 3500.4.2. NOT E: Mechanica l ventilation should be provided to minimize the accumulation of aerosol inablution facilities. For ventilation requirements, see AS 1668.2 or NZS 4303, as applicable.
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3.4 COMMISSIONING
Before being brought into service, all new or modified heated water systems shall becleaned, treated and commissioned by competent personnel in accordance withAS/NZS 3500.1.2 and AS/NZS 3500.4.2, as appropriate. All systems shall be provided withoperating and maintenance manuals in accordance with AS/NZS 3666.2.
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S E C T I O N 4 D E S I G N , I N S T A L L A T I O N A N DC O M M I S S I O N I N G O F C O O L I N G
W A T E R S Y S T E M S
4.1 GENERAL
4.1.1 Access for maintenance
Easy and safe access for cleaning, inspection and maintenance shall be available to andabout all plant, equipment and components covered in this Section. Relevant requirementsof AS 1470, AS 1657, AS/NZS 1892.1 and AS/NZS 2865 shall be complied with.
4.1.2 Provision for maintenance
Provision shall be made within the cooling water system to facilitate regular maintenance.Hosing down facilities complying with AS/NZS 3500.1.2 shall be provided to aid cleaning.
4.1.3 Water treatment systemsCooling water systems shall be provided with suitable, automatically controlled, water treatment systems for effective management of corrosion, scaling, fouling and microbialgrowth, including water treatment when water is first introduced into the system during theconstruction stage.
The cooling water system shall be designed for effective circulation to facilitate water treatment. There shall be no dead-legs.
NOT E: Balance/equalizing lines between cooling towers may act as dead legs.
4.1.4 Materials
Materials used for system components in contact with the cooling water, including O-rings,gland packings, gaskets, washers and lubricants shall be compatible with each other, shallnot foster microbiological growth nor react adversely with treatment, cleaning, disinfectionand decontamination chemicals. Copper and copper alloys shall comply with AS 2345.
4.1.5 Cooling towers
Cooling towers shall be fabricated from corrosion-resistant materials, and shall be designedfor ease of maintenance, particularly for cleaning of fill, water distribution system, basinand sumps. Tower fill shall be designed for effective in situ cleaning or capable of beingwithdrawn without damage for cleaning; withdrawable sections shall be of a practical sizefor handling. All internal surfaces including corners and edges of basins and sumps shall beconstructed to facilitate cleaning. Internal tower surfaces shall be smooth-faced. Provision
shall be made for quick draining and refilling. Isolating valves in drain lines shall be of thefull way type and be located at the start of the drain line. Basins and sumps shall bewatertight and graded to drain outlets, which shall be of 50 mm minimum internal diameter.Drains shall be continuously graded downward to prevent the collection of water. Draindischarges shall be located close to the equipment being serviced. All water supply anddrainage facilities shall comply with the requirements of AS/NZS 3500.2.1,AS/NZS 3500.2.2 and MP 52.
Drift eliminators shall be provided and installed so as to facilitate ease of inspection,cleaning and maintenance. They shall be designed for in situ cleaning or capable of beingwithdrawn, without damage, for cleaning. The drift eliminators shall extend across the air stream and air bypass shall be prevented. Provision shall be made to prevent splash-out
from the cooling tower.Cooling towers that undergo retrofit of components such as fill, basins or eliminators or anyupgrade for performance shall be required to meet all requirements associated with coolingtowers, of this Standard.
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NOT E: Cooling water sys tems can provide an environment that is favourable to the growth of microorganisms. Such organisms can be transported outside the cooling tower within driftaerosol. There is evidence that the inhalation of such drift containing Legionella is a means of infection.
4.2 PUMPS
The pump seal sump and pump casing shall be fitted with drain outlets and be separatelydrained to discharge in accordance with Clauses 2.8 and 2.9. Where stand-by pumps areused, the start sequence shall be automatically alternated.
NOT E: It is recommended that pumps be alternated twice weekly in order to effect water circulation.
4.3 LOCATION
Cooling towers shall be located so as to
(a) discharge exhaust away from occupied areas, pedestrian thoroughfares, air intakes,
(including lift vents), building openings and trafficable areas; and(b) avoid contamination from the exhaust discharges from food processing areas and
systems (such as kitchen exhaust effluent) or other cooling towers.
Cooling tower enclosures shall not interfere with the required airflow through the tower nor result in the recirculation of discharged air.
NOT ES: 1 The effluent of kitchen exhaust systems may hinder the control of microbial growth in
cooling towers. Kitchen exhaust should be discharged at a distance of not less than 8 m fromany cooling tower intake or discharge opening.
2 See AS 1668.2.
3 It has been found that, when cooling tower fans are idle, direction of airflow can be reversedunder some climatic conditions.
4.4 DRIFT CONTROL
The manufacturers tested value of maximum drift loss shall not exceed 0.002% at themaximum design water circulation rate through the tower, as determined under laboratoryconditions.
NOT E: Dri ft loss may be determined under laboratory cond itions in accordance wi th AS 4180.1.
4.5 CONTROL OF SOLIDS
Automatic bleed-off of a sufficient proportion of the circulating cooling water shall be provided to limit the build-up of dissolved and non-dissolved solids so as to minimizescaling and fouling in the cooling water system. Chemicals shall be added, as appropriate,to assist in limiting the build-up of non-dissolved solids and to minimize scaling, corrosionand fouling. The water shall be discharged in accordance with the regulations applying tothe installation site.
NOT ES: 1 Automatic systems provide more precise control by sensing the change in total dissolved
solids concentration with variation in evaporation load.
2 Automatic systems will usually operate by maintaining the water conductance at a presetvalue.
3 Filtration and separation systems can assist in the removal of non-dissolved solids.4 A lock out should be provided to prevent the bleed drain from operating while biocide is
being added to the sys tem.
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4.6 SUNLIGHT
Design, orientation and placement of cooling towers shall be such that direct sunlight isminimized from the wetted areas of the cooling tower.
NOT ES: 1 Algae growth in towers is dependent on the light available. Legionella and other bacteria feed
on algae.
2 Louvres may be necessary on inlets as well as outlets to exclude direct light.3 Light falling on the thin film of water on the outer surfaces of eliminator blades does not
appear to significantly contribute to algae growth in the circulating water.
4.7 COMMISSIONING
New cool ing water systems shall be flushed, chemically cleaned and pretreated for corrosion and microbial control purposes by competent personnel before being brought intoservice. New components installed within an existing installation shall be flushed,chemically cleaned and pretreated for corrosion and microbial control purposes prior to
connection within the installation. Adequate facilities shall be provided for flushing anddraining the complete system. This requirement shall also apply to stand-by units. Allsystems shall be provided with operating and maintenance manuals in accordance withAS/NZS 3666.2.
NOT ES: 1 A number of outbreaks of legionnaires disease have been due to new cooling water systems
having been commissioned without prior chemical treatment or cleaning.
2 Progressive flushing may be necessary for large systems.3 Information on facilities and relevant requirements may be obtained from environmental
protection authorities.
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NOTES
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