1、 ANSI/AWWA B506-13 (Revision of AWWA B506-06) AWWA Standard Effective date: June 1, 2013. First edition approved by AWWA Board of Directors Feb. 12, 2006. This edition approved Jan 10, 2013. Approved by American National Standards Institute April 3, 2013. 6666 West Quincy Avenue Advocacy Denver, CO
2、80235-3098 Communications T 800.926.7337 Conferences www.awwa.org Education and TrainingScience and TechnologySections The Authoritative Resource on Safe WaterZinc Orthophosphate SM Copyright 2013 American Water Works Association. All Rights Reserved. ii AWWA Standard This document is an American Wa
3、ter Works Association (AWWA) standard. It is not a specification. AWWA standards describe minimum requirements and do not contain all of the engineering and administrative information normally contained in specifi- cations. The AWWA standards usually contain options that must be evaluated by the use
4、r of the standard. Until each optional feature is specified by the user, the product or service is not fully defined. AWWA publication of a standard does not constitute endorsement of any product or product type, nor does AWWA test, certify, or approve any product. The use of AWWA standards is entir
5、ely voluntary. This standard does not supersede or take precedence over or displace any applicable law, regulation, or codes of any governmental authority. AWWA standards are intended to represent a consensus of the water supply industry that the product described will provide satisfactory service.
6、When AWWA revises or withdraws this standard, an official notice of action will be placed on the first page of the Official Notice section of Journal - American Water Works Association. The action becomes effective on the first day of the month following the month of Journal - American Water Works A
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10、conformity with particular American National Standards. Caution n oti Ce : The American National Standards Institute (ANSI) approval date on the front cover of this standard indicates completion of the ANSI approval process. This American National Standard may be revised or withdrawn at any time. AN
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12、ute, 25 West 43rd Street, Fourth Floor, New York, NY 10036; (212) 642-4900, or emailing infoansi.org. ISBN-13, print: 978-1-58321-933-1 eISBN-13, electronic: 978-1-61300-226-1 ISBN-10, print: 1-58321-933-1 eISBN-10, electronic: 1-61300-226-2 All rights reserved. No part of this publication may be re
13、produced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information or retrieval system, except in the form of brief excerpts or quotations for review purposes, without the written permission of the publisher. Copyright 2013 by American W
14、ater Works Association Printed in USA Copyright 2013 American Water Works Association. All Rights Reserved. iii Committee Personnel The AWWA Standards Committee on Scale and Corrosion Control Chemicals, which reviewed and approved this standard, had the following personnel at the time of approval: R
15、obert A. Ryder, Chair General Interest Members J.H. Bambei Jr.,* Denver Water, Denver, Colo. (AWWA) M.S. McFadden, HDR Engineering Inc., Bellevue, Wash. (AWWA) D. Orozco, Robert Cole and Vik, E.A., et al., Mitigation of Corrosion Effects (426). 1996. In Internal Corrosion of Water Distribution Syste
16、ms, 2nd ed. Denver, Colo.: American Water Works Association Research Foundation and DVGW-Technolgieszentrum Wasser. Copyright 2013 American Water Works Association. All Rights Reserved. viii zinc-to-orthophosphate ratios were used. Chemical costs change relatively rapidly, and the cost value of the
17、ratio may change. ZOP solutions are usually acidic, have a pH of less than 2, and are a hazardous chemical. Double containment of large storage vessels, piping, and other chemical handling safety measures are appropriate and required. ZOP in metal-corrosion suppression is believed to function by two
18、 direct mecha- nisms: film formation and electrochemical passivation. In metal-corrosion protection, the orthophosphate provides an anodic inhibitor, and zinc films form at the cathode and provide a cathodic inhibitor. The blockage of both anodic and cathodic corrosion sites provides a double interr
19、uption of the electrochemical-corrosion reaction, which can be more effective than a single-acting inhibitor, which is typical for other phos- phate or silicate chemicals. Asbestoscement pipe, concrete pipe, or cement linings can be protected by zinc carbonate film, which minimizes aggressive (less
20、than zero Langelier Index) water from leaching calcium and deteriorating the cement surface. There is no apparent benefit of the orthophosphate in cement protection, and other zinc formulations, including zinc chloride, can be used. However, ZOP can be a wide-ranging corrosion inhibitor for multiple
21、 pipe and reservoir materials of water distribution and consumer plumbing systems. Typically, maximum ZOP dosages are limited to between 5 mg/L and 30 mg/L, depending on supplier qualifications of NSF*/ANSI 60, Drinking Water Chemicals Health Effects, testing in the United States. The supplier can p
22、rovide operators with appropriate information on certification and dosage limit of the product for use in pota- ble water. German and other European potable water standards do not allow the use of zinc in chemicals added to potable water, and the possible use of ZOP as a corrosion inhibitor must be
23、evaluated in each country for its intended use. The zinc concentration is frequently limited to between 0.2 and 2 mg/L to avoid water system secondary-contaminant limits and wastewater and effluent-discharge toxicity limits. However, as is typical for most corrosion inhibitors, it is necessary to us
24、e a passivating dose of three to five times the maintenance inhibitor dose for a month or more to reach all portions of the distribution system and initially passivate the metal to provide the protective films. Phosphate concentrations should typically be in the range of 0.5 to 2 mg/L as P. Sometime
25、s, phosphate may stimulate bacteria and bioslime growths, particularly in * NSF International, 789 N. Dixboro Road, Ann Arbor, MI 48105. Copyright 2013 American Water Works Association. All Rights Reserved. ix warmer water and where chloramination disinfection is practiced. There have been instances
26、 in warmer waters in Hawaii and the southeastern United States where elevated heterotrophic bacteria counts and other microbiological organisms have caused skin rashes in people bathing.* This possibility should always be considered when evaluating a phosphate corrosion inhibitor. It is highly desir
27、able to test and evaluate the effectiveness of various combina- tions of zinc-to-phosphorus ratios and at various dosages by both instrumentation and pipe-coupon pilot plant tests. Control tests of no inhibitor, orthophosphate without zinc, and at various pH and alkalinity values should be evaluated
28、 in order to select the optimum corrosion-inhibitor concentration for iron, steel, copper, lead, and cement protection. It is also quite likely that type, strategy, and temperature effects will result in use of a larger inhibitor dose in summer warm-water temperature conditions than in winter. Eithe
29、r in situ metal coupon, real-time linear polarization, or electrochemi- cal noise measurements may optimize inhibitor dosage for changing water conditions. Inhibitor dosage control may be automated, such as by linear polarization or electro- chemical noise sensors using programmable logic controller
30、s (PLCs). The water characteristics that are most important when applying ZOP in corro- sion protection are pH, alkalinity, hardness, and temperature. The optimum pH for use of ZOP is 7.27.8, and ZOP optimum dosage rates are typically lower in elevated pH and colder waters. ZOP should not be fed to
31、water exhibiting a pH above 8.1 to avoid premature precipitation of the zinc and undesirable turbidity or particulates in the distributed water. Much of the success with ZOP as a corrosion inhibitor has been obtained in waters exhibiting low-to-moderate hardness and alkalinity. A recognized limitati
32、on of using a ZOP corrosion inhibitor is contribution of the zinc loading at the wastewater treatment plant and in the effluent discharged to surface waters. This is sometimes regulated to be as low as 0.5 mg/L or lower, and effluent toxicity limits may be lower than 0.1 mg/L. Another recognized eff
33、ect of using ZOP corrosion inhibitor is consumption of alkalinity and possible reduction in water pH, typically by 0.1 to 0.2 units. Formulations with low zinc content may provide effective corrosion suppression while meeting wastewater regulations. Many different ratios are available from suppliers
34、. * Edwards, M., B. Marshall, Y. Zhang, & Y.-J., Lee. 2005. Unintended Consequences of Chloramination Hit Home. In Proc. Disinfection 2005, Feb. 69, 2005, Mesa, Ariz. Water Environment Federation, Alexandria, Va. Internal Corrosion of Water Distribution Systems. 2nd Edition. 1996. Ch. 9, Corrosion A
35、ssessment Technologies. Water Research Foundation, Denver, Colo. Copyright 2013 American Water Works Association. All Rights Reserved. x Typically, zinc is measured in the water at the end of distribution systems to pro- vide an indication that the inhibitor dosage is sufficient to reach all portion
36、s of the piping system. Because of the corrosion inhibitors filming effect, it is possible to have the dosage interrupted for several days to perhaps a week and not seriously compromise corrosion protection, if the maintenance dose is resumed. I.B. History. The first edition of ANSI/AWWA B506, Stand
37、ard for Zinc Orthophosphate, was approved by the AWWA Board of Directors on Feb. 12, 2006. This edition was approved on Jan. 20, 2013. I.C. Acceptance. In May 1985, the US Environmental Protection Agency (USEPA) entered into a cooperative agreement with a consortium led by NSF International (NSF) to
38、 develop voluntary third-party consensus standards and a certification program for direct and indirect drinking water additives. Other members of the original consortium included the American Water Works Association Research Foundation (AwwaRF, now Water Research Foundation*) and the Conference of S
39、tate Health and Environmental Managers (COSHEM). The American Water Works Association (AWWA) and the Association of State Drinking Water Administrators (ASDWA) joined later. In the United States, authority to regulate products for use in, or in contact with, drinking water rests with individual stat
40、es. Local agencies may choose to impose requirements more stringent than those required by the state. To evaluate the health effects of products and drinking water additives from such products, state and local agencies may use various references, including two standards developed under the direction
41、 of NSF, NSF/ANSI 60, Drinking Water Treatment ChemicalsHealth Effects, and NSF/ANSI 61, Drinking Water System ComponentsHealth Effects. Various certification organizations may be involved in certifying products in accor- dance with NSF/ANSI 60. Individual states or local agencies have authority to
42、accept or accredit certification organizations within their jurisdiction. Accreditation of certi- fication organizations may vary from jurisdiction to jurisdiction. Annex A, “Toxicology Review and Evaluation Procedures,” to NSF/ANSI 60 does not stipulate a maximum allowable level (MAL) of a contamin
43、ant for substances not regulated by a USEPA final maximum contaminant level (MCL). The MALs of an unspecified list of “unregulated contaminants” are based on toxicity testing guidelines * Water Research Foundation, 6666 W. Quincy Ave., Denver, CO 80235. Persons outside the United States should contact the appropriate authority having jurisdiction. Copyright 2013 American Water Works Association. All Rights Reserved.
