1、EWRVASCE 35-01 American Society of Civil Engineers Guidelines for Quality Assurance of Installed FinemPore Aeration Equipment 4SCE EWRVASCE 35-01 American Society of Civil Engineers Guidelines for Quality Assurance of Installed FinemPore Aeration Equipment This document uses both Systme Internationa
2、l (SI) and customary units. Published by the American Society of Civil Engineers 1801 Alexander Bell Drive Reston, Virginia 20191-4400 ABSTRACT Guidelines for Quality Assurance of installed Fine-Pore Aeration Equipment provides several techniques and guidance for use in de- veloping quality assuranc
3、e requirements for specifying fine-pore aeration equipment. Three methods for specifying compliance test- ing are outlined. Two are based on conducting oxygen transfer shop tests and the third is based on conducting full-scale oxygen transfer testing. The basis for compliance testing includes oxygen
4、 transfer testing of selected individual diffusers or two reference tests-dy- namic wet pressure and effective flux ratio. A description of test pro- cedures and diffuser sampling is provided. Library of Congress Cataloging-in-Publication Data Guidelines for quality assurance of installed fine-pore
5、aeration equipment/American Society of Civil Engineers. Includes bibliographical references and index. p. cm. ISBN O-7844-0593-X 1. Sewage-Purification-Aeration. 2. Quality assurance. 1. American Society of Civil Engineers. TD758.G85 2001 628.35421 2001055973 The material presented in this publicati
6、on has been prepared in ac- cordance with generally recognized engineering principles and prac- tices, and is for general information only. This information should not be used without first securing competent advice with respect to its suitability for any general or specific application. The content
7、s of this publication are not intended to be and should not be construed to be a standard of the American Society of Civil Engineers (ASCE) and are not intended for use as a reference in purchase of specifications, contracts, regulations, statutes, or any other legal document. No reference made in t
8、his publication to any specific method, product, process, or service constitutes or implies an endorsement, recommendation, or warranty thereof by ASCE. ASCE makes no representation or warranty of any kind, whether express or implied, concerning the accuracy, completeness, suitability, or utility of
9、 any information, apparatus, product, or pro- cess discussed in this publication, and assumes no liability therefore. Anyone utilizing this information assumes all liability arising from such use, including but not limited to infringement of any patent or patents. ASCE and American Society of Civil
10、Engineers-Registered in U.S. Patent and Trademark Office. Photocopies: Authorization to photocopy material for internal or personal use under circumstances not falling within the fair use pro- visions of the Copyright Act is granted by ASCE to libraries and other users registered with the Copyright
11、Clearance Center (CCC) Transactional Reporting Service, provided that the base fee of $8.00 per chapter plus $.50 per page is paid directly to CCC, 222 Rose- wood Drive, Danvers, MA 01923. The identification for ASCE Books is 0-7844-0593-X/02/$8.00 + $SO per page. Requests for special permission or
12、bulk copying should be addressed to Permis- sions the third is based on conducting full-scale on-site OTE tests. Performance data should be selected in concert with the equipment manufacturers named in the specifications. The difference between the two shop-test methods is in whether the manufacture
13、r of the aeration equip- ment practices quality control in the diffuser manufac- turing process. If the diffuser manufacturing process includes a quality control program, the shop test and field verification of proper installation should be ade- quate to assure quality. If the diffusers are manufac-
14、 tured without quality control in the manufacturing pro- cess, shop testing with field verification that the diffusers shipped to the plant are equivalent to the shop-tested diffusers is necessary. The availability of quality control data does not have a direct effect on the full-scale test method b
15、e- cause the decision regarding acceptance of the aeration system is based on the results of testing the actual in- stalled system. However, the probability of acceptance is expected to be significantly higher if the manufac- tured lots of diffusers have passed quality control test- ing criteria. 4.
16、1 Shop Testing with Quality Control Data 4.1.1 Description The procedure is to run clean-water oxygen trans- fer tests on a random sample of diffusers taken from a representative lot and installed in a shop-test tank. The aeration system tested in the shop facility must resem- ble the full-scale aer
17、ation system configuration. The diffusers used in the shop test must be representative of the units that will be manufactured for installation in the full-scale system. Quality control data are used to verify that the diffusers used in the shop test and those manufactured for installation in the pla
18、nt basins are equivalent. 4.1.2 Application Shop testing is appropriate for any aeration system configuration that can be reasonably modeled in the shop-test facility. The following criteria should be used to simulate field conditions as closely as possible: water depths should be similar and prefer
19、ably identi- cal, width-to-depth ratios for spiral roll systems should be similar, potential interference resulting from wall effects and any extraneous piping or other materiais in the tank should be minimized, and density of aerator placement, airflow per unit volume or area, and power input per u
20、nit volume should be similar. 4.1.3 Advantages Shop testing can and should be conducted early in the project so that any failure to meet performance can be corrected before the overall project schedule is de- layed. This minimizes the possibility that equipment not meeting the project?s performance
21、goals is ac- cepted. fuser densities, each diffuser configuration should be tested separately. The overall basin performance can then be calculated using the results of the separate tests. full-scale on-site tests. The reduction in cost per test can be used to reduce the overall project costs or to
22、conduct more tests at various air flow rates, which can be used to evaluate future operational modes. Using data collected as part of a quality control program practiced during the manufacturing process is the most cost-effective way to provide the informa- tion necessary for quality assurance of th
23、e installed air diffusion system. Because the decision regarding acceptability can be made before any diffusers are shipped to the job site, the cost of returning rejected lots and replacing them with acceptable units is avoided. In basins that have several grids with different dif- The costs of sho
24、p tests are much less than those of 3 GUIDELINES FOR QUALITY ASSURANCE OF INSTALLED FINE-PORE AERATION EQUIPMENT 4.1.4 Disadvantages system is not tested. This should not be a major con- cern as long as the aeration system tested in the shop facilities meets the criteria for scaling the configuratio
25、n and testing is conducted to show that the diffusers in- stalled in the full-scale system are equivalent to the units tested in the shop. As with any shop-test method, the actual installed 4.1.5 Procedure In this procedure, it is necessary to have the quality control data for the lot of diffusers f
26、rom which the shop-test units are obtained and for the lots identified for shipment to the site for installation. To ensure that the quality control data are collected ac- cording to the quality control sampling plan and tested in accordance with specified procedures, the engineer-owner should witne
27、ss the quality control sampling and testing at the manufacturing facility. The right to witness quality control activities should be included in the project specifications. Once the quality control data are provided for, the following steps should be followed to complete the shop test and data analy
28、sis: 1. 2. 3. 4. 5. 6. 4 Determine the number of diffusers required for the shop test using the guidelines presented in 4.1.2. Install the diffusers in the test tank and fill the tank with clean water to the desired level for oxygen transfer testing. Conduct clean-water tests in accor- dance with th
29、e ASCE standard. Save the diffusers for future reference. They could be shipped to the plant site and used in the full-scale installation, stored for future testing, or stored for use as replacements. Compare DWP and EFR results for the lot of dif- fusers from which the shop-test units were collecte
30、d to the data for the lots to be shipped to the job site to determine if they are equivalent. The t test is a statistical procedure used for comparing two data sets3. If a lot of diffusers is shown to be equivalent, they can be shipped to the job site and installed. Before final acceptance, each sys
31、tem should be operated with a few inches of clean water over the diffusers to ensure that there are no leaks and the system has been installed level. If a lot of diffusers is not equivalent, it is set aside and another lot is evaluated before shipping. In this way, only acceptable lots are actually
32、shipped to the job site for installation. 4.2 Shop Testing Without Quality Control Data 4.2.1 Description The procedure is to run clean-water oxygen trans- fer tests and make differential pressure measurements on a random sample of diffusers taken from a represen- tative lot and installed in a test
33、tank. The aeration sys- tem tested in the shop facility must resemble the full- scale aeration system configuration. The diffusers used in the shop test must be representative of the units that will be manufactured for installation in the full-scale system. Because quality control data are not avail
34、able to show that the diffusers used in the shop test and those manufactured for installation in the plant basins are equivalent, reference tests are conducted on the test aeration system at the time the shop tests are per- formed and are repeated at the project site on a sample of diffusers taken f
35、rom the lots delivered for full-scale installation. 4.2.2 Application Shop testing is appropriate for any aeration system configuration that can be reasonably modeled in the shop-test facility. The following criteria should be used to simulate the field conditions as closely as possible: water depth
36、s should be similar and preferably identical, width-to-depth ratios for spiral roll systems should be similar, potential interferences resulting from wall effects and any extraneous piping or other materials in the tank should be minimized, and the density of aerator placement, air flow per unit vol
37、ume or area, and power input per unit volume should be similar. 4.2.3 Advantages Shop testing can and should be conducted early in the project so that any failure to meet performance can be corrected before the overall project schedule is de- layed. This minimizes the possibility that equipment not
38、meeting the projects performance goals will be accepted. fuser densities, each diffuser configuration can be tested separately. The overall basin performance can then be calculated using the results of the separate tests. full-scale on-site tests. The reduction in cost per test can be used to reduce
39、 the overall project costs or to conduct more tests at various air flow rates, which can be used to evaluate future operational modes. In basins that have several grids with different dif- The costs of shop tests are much less than those of EWRI/ASCE 35-01 4.2.4 Disadvantages Conducting reference te
40、sts on the diffusers used in the shop tests and repeating the tests on-site before the diffusers are installed is more costly than quality con- trol by the manufacturer as part of the manufacturing process. system is not tested. This should not be a major con- cern as long as the aeration system tes
41、ted in the shop facilities meets the criteria for scaling the configuration and testing is conducted to show that the diffusers in- stalled in the full-scale system are equivalent to the units tested in the shop. As with any shop-test method, the actual installed 4.2.5 Determining Sample Size Volk3
42、describes a procedure and presents tables that give the minimum sample size needed for the t test to determine if the difference between two means is significant. The tables are for use with symmetrical and unsymmetrical t tests. Symmetrical testing is used when the measured means can be either grea
43、ter than or less than the true mean. For example, if DWP is being used to character- ize diffusers, there is cause for rejection if the mean of the sample is significantly greater than or less than the specified mean. Diffusers with high DWP take too lit- tle air, diffusers with low DWP take too muc
44、h, result- ing in poor air flow distribution. Unsymmetrical testing is used to establish whether the true mean is either less than or greater than some theoretical value, but not both. If the EFR is being used to characterize diffusers, the hypothesis should be rejected only if the EFR is significan
45、tly greater than the specified value. EFRs less than or equal to the specified value are considered uniform, and there is no concern about being perfectly uni- form. (Y, the probability that an acceptable lot of diffusers will be rejected (PAR), probability that an unacceptable lot of diffusers will
46、 be accepted (PUA), and the differ- ence in the means to be investigated. The standard de- viation must also be known or estimated. PAR should be minimized because the risk of false rejection will undoubtedly be included in the cost of the equipment. The higher the risk taken on by the manufacturer,
47、 the higher the cost of the equipment. On the other hand, using a very low PAR value increases the probability of falsely accepting a bad lot, which could affect the overall performance of the aeration system. The optimum value of PAR typically lies in the range of 0.01 to 0.05. To use the procedure
48、, values must be selected for PUA needs to be minimized because a bad lot could adversely affect performance of the aeration sys- tem. Another factor to consider is the cost of testing the selected diffusers because for a fixed value of PAR, decreasing PUA increases the sample size. Typically, PUA v
49、alues in the range of 0.01 to O. 1 are used. collected during routine quality control testing. If the data are collected from many manufacturing lots, the resulting sample standard deviation will be a good esti- mate of the population standard deviation. The values selected for PAR and PUA should be based on evaluation of the risk that accepting a bad lot will have on aeration system performance. If data are available that show what difference is significant in terms of the effect on OTE, this value could be used for the difference. In the absence of such data, reason- able sample sizes ar
