【AS澳大利亞標(biāo)準(zhǔn)】AS NZS 3666.3-2000 Air-handling and water systems of buildings - Microbial control - Performance-based maintenance of cooli.docVIP

licensed to marley temcel australia on 05 jul 2001. single user licence only. storage, distribution or use on network prohibited.as/nzs 3666.3as/nzs 3666.3:2000australian/new zealand standardair-handling and water systems of buildings microbial controlpart 3:performance-based maintenance of cooling water systemsthe standard is downloaded from standard sharingas/nzs 3666.3:2000this joint australian/new zealand standard was prepared by joint technical committee me/62, ventilation and airconditioning. it was approved on behalf of the council of standards australia on 4 august 2000 and on behalf of the council ofstandardsnew zealandon10 august 2000.itwas publishedon1 september 2000.the following interests are represented on committee me/62:air-conditioning and refrigeration equipment manufacturers association ofaustraliaaustralasian fire authorities councilaustralian buildings code boardaustralian chamber of commerce and industryaustralian industry groupaustralian institute of building surveyorsaustralian institute of refrigeration airconditioning and heatingchartered institution of building services engineersdepartment of contract and management services, w.a.enhealth councilfpa australialicensed to marley temcel australia on 05 jul 2001. single user licence only. storage, distribution or use on network prohibited.institute of refrigeration heating and air conditioning engineers of new zealandinstitute of engineers australiaplastics and chemicals industries associationproperty council of australiathermal insulation contractors association of australiaadditional interests participating in the preparation of this standard: department of human services (vic)institute of plant engineers australasianational health and medical research councilnsw health departmentqueensland healthtelstra corporationkeeping standards up-to-datestandards are living documents which reflect progress in science, technology and systems. to maintain their currency, all standards are periodically reviewed, and new editions are published. between editions, amendments may be issued. standards may also be withdrawn. it is important that readers assure themselves they are using a current standard, which should include any amendments which may have been published since the standard was purchased.detailed information about joint australian/new zealand standards can be found by visiting the standards australia web site at .au or standards new zealand web site at www.standards.co.nz and looking up the relevant standard in the on-line catalogue.alternatively, both organizations publish an annual printed catalogue with full details of all current standards. for more frequent listings or notification of revisions, amendments and withdrawals, standards australia and standards new zealand 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 especially encourage readers to notify us immediately of an y apparent inaccuracies or ambiguities. please address your comments to the chief executive of either standards australia international or standards new zealand at the address shown on the back cover.this standard was issued in draft form for comment as dr 00101.licensed to marley temcel australia on 05 jul 2001. single user licence only. storage, distribution or use on network prohibited.as/nzs 3666.3:2000australian/new zealand standardair-handling and water systems of buildingsmicrobial controlpart 3:performance-based maintenance of cooling water systemsoriginated as as/nzs 3666.3(int):1998.jointly revised and designated as/nzs 3666.3:2000.copyright standards australia/standards new zealandall rights are reserved. no part of this work may be reproduced or copied in any form or by any means, electronic or mechanical, including photocopying, without the written permission of the publisher.jointly published by standards australia international ltd, gpo box 5420, sydney, nsw 2001 and standards new zealand, private bag 2439, wellington 6020isbn 0 7337 3555 xas/ nzs 3666.3:20003the standard is downloaded from standard sharingprefacethis standard was prepared by jointstandardsaustralia/standardsnew z ealandcommittee me/62, ventilation and airconditioning.this standard forms part 3 of a series of standards for microbial control of air-handling and water systems, as follows:as/nzs3666air-handling and water systems of buildings microbial control3666.1part 1:design, installation and commissioning3666.2part 2:operation and maintenance3666.3part 3:performance-based maintenance of cooling water systemslicensed to marley temcel australia on 05 jul 2001. single user licence only. storage, distribution or use on network prohibited.the term normative has been used in this standard to define the application of the appendix to which it applies. a normative appendix is an integral part of a standard.licensed to marley temcel australia on 05 jul 2001. single user licence only. storage, distribution or use on network prohibited.contentspageforeword . 4section 1 scope and general1.1scope . 61.2objective . 61.3functional statement . 61.4performance requirements. 61.5referenced documents . 61.6definitions . 71.7testing . 7section 2 identification and assessment of risk factors2.1scope of section. 82.2risk factors . 82.3risk assessment . 82.4water treatment . 8section 3 performance monitoring and control3.1scope of section. 103.2presence of legionellae . 103.3presence of other heterotrophic microorganisms. 103.4water quality management . 103.5water temperature . 113.6start up . 133.7results and records . 133.8evidence of compliance. 13appendicesacooling water sampling procedure. 16bon-line disinfection procedure for cooling water systems . 18cdecontamination procedures for cooling water systems . 19as/ nzs 3666.3:20005the standard is downloaded from standard sharingforewordas/nzs 3666.2, air-handling and water systems of buildingsmicrobial control, part 2: operation and maintenance, requires shutdown of cooling water systems for periodic cleaning. this is impracticable for many systems, such as the large industrial types serving power stations, co-generation plants and refining plants. however, microbiological control at these plants is usually effective and no reported outbreaks of legionnaires disease have been attributed to such sources. the continuous engineering attention they receive means they are generally well maintained. however, it became apparent that the as/nzs 3666 series should provide for a performance-based alternative to the prescriptive maintenance requirements set out in clause 2.5 of as/nzs 3666.2. this performance-based alternative can be applied to any cooling water system for which the specific requirements of this standard can be met.this standard provides such an alternative option. it follows risk management principles including(a)risk identification and assessmentlicensed to marley temcel australia on 05 jul 2001. single user licence only. storage, distribution or use on network prohibited.(b)control; and(c)monitoring and corrective actions.these principles are applied to the key causal factors, understood to lead to a risk of multiplication of legionellae within a system, as set out in the foreword to as/nzs 3666.1.a central issue in the management of health risk arising from microorganisms is the degree of scientific certainty about the underlying causes of growth, dissemination and infection. control strategies adopted may need to change as new knowledge becomes available.sampling for legionellae is not required by as/nzs 3666.2 but is considered to be a relevant monitoring activity in a performance-based approach. although the sample taken may not accurately represent the microbial distribution and variety within the system, it is presently the most direct means of assessing the effectiveness of maintenance regimes on the multiplication of legionellae. such specific tests need to be complemented with other assessments such as total bacterial count (also called heterotrophic colony count) and system water quality characteristics to provide reassurance that the system is well maintained and operating in a hygienic condition.the concentration level of legionellae required to cause infection has not been established at this time. the risk of disease depends substantially on the susceptibility of the person exposed. however, it is reasonable to assume that increased risk is associated with exposure to increased concentrations of microorganisms. available data suggest that most outbreaks are associated with a concentration of 1000 cfu/ml or greater, although lower levels may well be associated with sporadic cases of disease. it is the intention of this standard that cooling water systems operate with non-detectable concentrations of legionellae. this standard requires corrective actions to be carried out whenever a detectable concentration of legionellae is found (10 cfu/ml or greater) in order to provide confidence that the system is hostile to these microorganisms. more demanding and prompt actions are required when a higher concentration is detected.the primary aim is to avoid conditions that may allow microorganisms, including legionellae to multiply in the cooling water system thus creating a health risk.an important strategy in minimizing health risks associated with cooling water systems involves the management of system water quality. water treatment is designed to preserve the cooling tower and the cooling water system of which it is a part, maintain heat transfer efficiency and help ensure an acceptable standard of occupational and public health. theselicensed to marley temcel australia on 05 jul 2001. single user licence only. storage, distribution or use on network prohibited.factors interact so that properly implemented microbial control, for reasons of disease prevention, should also assist in system longevity and efficiency. the water treatment program for microbial control needs to be well managed, and be more comprehensive than a program for those systems that are routinely cleaned in accordance with as/nzs 3666.2. water treatment program management approaches may differ in detail from site to site and, therefore, need to be documented in a specific plan for each site.this standard addresses only the maintenance of cooling water systems and is to be read in conjunction with part 1 and the relevant clauses of part 2. aspects such as maintenance manuals, records, log books, safety procedures and the like, are as important for the application of this standard, as they are for a prescriptive approach to maintaining a clean system.further explanatory information regarding the subject of microbial control of cooling water systems can be found in the standards australia/standards new z ealand handbook saa/snz hb32:1995, control of microbial growth in air-handling and water systems of buildings, and the national environmental health forum monograph, guidance for the control of legionella, published by the south australian health commission (1996) on behalf of the commonwealth department of health and aged care, and the application manual no. da18, water treatment, which is published by the australian institute of refrigeration air-conditioning and heating inc (airah).as/ nzs 3666.3:200013the standard is downloaded from standard sharingstandards australia/standards new zealandaustralian/new zealand standardair-handling and water systems of buildingsmicrobial controlpart 3: performance-based maintenance of cooling water systemss e c t i o n1s c o p ea n dg e n e r a l1.1 scopelicensed to marley temcel australia on 05 jul 2001. single user licence only. storage, distribution or use on network prohibited.this standard outlines a performance-based approach to the maintenance of cooling water systems with respect to the control of microorganisms, including legionellae, within such systems. this approach combines automatically regulated water treatment with monitoring, assessment and control strategies to help create a low risk environment within the cooling water system.the provisions of this standard are an alternative to the prescriptive requirements ofas/nzs 3666.2 for the maintenance of cooling water systems.note: this standard addresses only the performance of maintenance programs for cooling water systems and is to be read in conjunction with part 1 and the relevant clauses of part 2. aspects such as maintenance manuals, records, log books, safety procedures, and the like, are as important for the application of this standard as they are for a prescriptive approach to maintaining a clean system.1.2 objectivethe objective of this standard is to provide a performance-based approach to cooling water system maintenance to assist users in the control of microorganisms, including legionellae, within such systems.1.3 functional statementcooling water systems shall be maintained and monitored to minimize the growth and dissemination of microorganisms, and in particular, legionellae in and by such systems.1.4 performance requirementsthe monitoring, assessment and control strategies for key performance indicators shall be in accordance with section 3.note: following these performance requirements is deemed to comply with the prescriptive requirements of clause 2.5 of as/nzs 36 referenced documentsthe following documents are referred to in this standard. as2031selection of containers and preservation of water samples for chemical and microbiological analysis2031.2part 2:microbiological4276water microbiology4276.3.1method 3.1:heterotrophic colony count methodspour plate method using plate count agarcopyrig htlicensed to marley temcel australia on 05 jul 2001. single user licence only. storage, distribution or use on network prohibited.as/nzs3666air-handling and water systems of buildingsmicrobial control3666.1part 1:design, installation and commissioning3666.2part 2:operation and maintenance3896watersexamination for legionellae including legionella pneumophila4360risk management1.6 definitionsfor the purposes of this standard the definitions given in as/nzs 3666.1, as/nzs 3666.2 and those below apply.1.6.1 cycles of concentrationthe degree of concentration of the dissolved solids of the cooling system make-up water as a result of the evaporation that takes place in the cooling tower.note: the degree of concentration of the dissolved solids is typically determined from the ratio between the chlorides in the cooling water and the chlorides in the make-up water.1.6.2 key performance indicatora risk factor that is identified as testable, assessable and controllable for the performance, monitoring and verification of the system.1.6.3 total dissolved solids (tds)the total weight of dissolved solids in water, which would remain if all the water were evaporated.1.7 testingmicrobiological tests