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Robert Hill and Walter W. Schuk City of Houston

Walter W. Schuk, Inc.

The Water and Wastewater Instrumentation Testing Association of North America (ITA) is a not-fur-profit corporation dedicoted to improving the performance and relialn'lity of instrumentation used in the water and wastewater industries. Since its founding in 1984,/TA's goal has been to conduct evaluations of instrumentation through pooling of funds from its members. This pooling has allowed comprehensive and objective testing at a fraction of the cost to e~ch individual member. It is this foundation of cooperation and commitment upon which the association has grown. In addition to the actual instrumentation testing, ITA provides a number of other vital services to its members including: (1) access to the ITA clearinghouse, an up-to-the minute source (comput~ data base) of instrumentation information; (2) monthly newsletters and special bulletins providing valuable industry updates; (3) technical w o r k s h o p s and seminars designed in response to member's needs and interests ( ITA recently completed a series of four workshops on flow measurement; a work-

shop on general instrumentation and cntrol is planned for ~992); (4) sponsoring of research by other agencies (ITA is a cont~buting member to the National Institute of Standards and Technology (formerly the National Bureau of Standards) in their program on non-ideal flow metering); (5) instrumentation designer's cn~_cklists; (6) access to results of tests conducted independently by other ITA members (ITA also provides technical assistance in preparing test protocols and procedures for member agencies);

(7) an annual membership meeting where members can interact, share ideas and information, and formulate .,_~o strategies for the organization (a seminar and equipment show on programmable logic controllers was presented at ITA's 1991 annual meeting). ITA presently (August 199~) has fiflyrseven members including major U.S. and Canadian municipalities, leading engineo ing consultants, regulatory ag~cies, and

ISSN 0019-05781921011010317152.50© ISA 1992

two European groups. More information about ITA can be obtained from the corporate headquarters at 1225 Eye Street, N.W., Suite 300, Washington, D.C., 20005 (202/682-3760 extension 207).

HISTORYOF ITA From the first attempts ~t automat-ion in the water and wastm :ater i n d u s t r i e s , t h e r e w a s recognition of a great need for better instrumentation. Data from an early 1970's EPA s u r v e y cond u c t e d by Raytheon indicated that most of the primary sensors required for automation of water and wastewater treatment processes were performing poorly or not at all. The proceedings of an E P A - s p o n s o r e d w o r k s h o p at Clemson University in the fall of 1973 listed "improved primary sensors" as a first pffority requirement for improving the performance of treatment plants. Both vendors and users present at the w o r k s h o p agreed that conventional specifications were not adequate in defining the performance expected of the sensors u n d e r field conditions. Many of the early limited successes (and failures) indicated that better instruments and better information on existing instruments VOLUME 31 o NUMBER 1 • 1992

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WATERAND WASTEWATERTREATMENT INSTRUMENTATION

Many of the early limited successes (and failures) indicated that better instruments and better information on existing instruments were needed. were needed. In 1976 the User to-day operations are provided by Consortium, an advisory commit- a professional management firm. tee, formed by the EPA to estab- The Board of Directors are suplish and prioritize research needs, ported by four main committees recommended that an instrumen- and subcommittees as required. The Technical Committee detation testing program be impler=,ented. In response, the EPA velops the test protocols, oversees sponsored a feasibility study by the actual instrument testing proPTI to determine the social, legal, gram, and develops technical buleconomic, and technical factors letins such as the d e s i g n e r associated with founding a testing checklists. The Seminar Committee orgainstitute. PTI's final 1979 report recommended that a testing insti- nizes technical workshops and tute be founded. PTI also pro- seminars. The Program Committee sets vided guidelines for the corporate structure of the institute and the directions and policies for ITA. The Membership Committee is m e c h a n i s m s for c o n d u c t i n g responsible for development of equipment tests. Based on the recommendation ITA membership. of the PTI report, the EPA funded

Detailed instrument test reports are among ITA's most important products. a grant to the American Public Works Association (APWA) Research Foundation to found a testing institute. As a result of this grant, the Instrumentation Testing Service of North American (ITS) was incorporated in early 1984. The n a m e was later (1989) c h a n g e d to the Water and Wastewater Instrumentation Testing Association of North America (ITA) to better reflect the organization's mission and structure.

DESCRIPTIONOF THE ITA ORGANIZATION ITA is governed by a Board of Directors elected from the general membership. The Executive Director, national office, and all dayt 04

ISA TRANSACTIONS

SERVICES OF ITA ITA provides many products and services to its members including instrument test reports, an instrument clearinghouse (data base) service, monthly newsletters, special bulletins, workshops and seminars, designer checklists, and biannual meetings. More detailed explanations of each product and service follows.

seven different manufacturers representing the majority of the market for that particular parameter. The reports provide instrument designers and users with sufficient information to make informed instrument selections and purchases for their particular applications. Some test reports are available to ITA members free of charge. More recent tests (1990 and later) are available to members for a participation charge. Tables 1, 2, and 3 are listings of currently available test reports, tests presently in progress, and future tests in which development of the protocols has begun.

Development of Test Protocols All ITA tests are based upon written protocols developed by ITA's Technical Committee and reviewed by outside experts and the instrument manufacturers themselves. Thus, the test protocols are peer-reviewed consensus documents. A schematic of the protocol development process is shown in Figure 1. Whenever possible, the protocol references industry test standards by the Water Pollution Control Federation (WPCF), the Scientific Apparatus Manufacturers Association (SAMA), the Instrument Society of America (ISA), and other standards setting organizations.

Test Laboratory and Test Procedures

ITA does not maintain any pc;manent testing facilities or any testing personnel. Instead, ITA contracts the actual testing to a test laboratory selected by the Testingof Instruments Board of Directors. The laboraDetailed instrument test re- tory is responsible for taking the ports are among ITA's most im- test protocol, which describes the portant products. Each report work of interest, and developing a includes testing results on a single more detailed test procedures type of instrument such as dis- document. The test procedures solved oxygen or free residual describe specifically how the prochlorine analyzers. Tests typically tocol will be realized with the speinclude analyzers from four to cific i n s t r u m e n t s u n d e r test.

THE INSTRUMENTATION TESTING ASSOCIATION

Date 1985 1988 1989 1990 1990 1991 1991

Report Title Total Chlorine Residual Analysis Dissolved Oxygen Analyzers Performance Evaluation of FIowmeters for Wastewater Collection System Applications Total Chlorine Residual Analyzers Free Chlorine Residual Analyzers Low Concentration Total Suspended Solids Analyzers Medium Concentration Total Suspended Solids Analyzers

Table 1-Available InstrumeutTest Reports Date 1992 1993

Report Title Verification of Large Effluent Flow Meters High Concentration Total Suspended Solids Analyzers

Table 2-Tests In Progress Ammonia Analyzers Sludge Blanket Instruments Automatic Sampler

Table 3-Future Tests (Protocolsunder Development) Experimental apparatus, data acquisition e q u i p m e n t , Q A / Q C procedures, and detailed test procedures are covered in the procedures document. This document is also reviewed and approved by the same procedures as the test protocol.

Test Protocol The test protocol attempts to provide information on operational conformance and maintenance requirements at conditions typical of the water and wastewater industries. Test protocols typically include a bench test, a field test, and a general analysis of design, as shown in Figure 2. Bench test. The bench phase o( the testing program attempts to measure instrument performance under highly controlled laboratory conditions. The tests are conducted in aa environmentally secure room with corm'oiled temperature and humidity. By varying only one parameter (i.e., sample temperature) at a time, in-

dependent of other influences, the sponding bench tests in that they effect of this single parameter can are conducted on installed anbe ascertained. A partial list of alyzers and include both instrutypical bench tests are shown in ment and process noise. A partial Figure 3. list of typical field tests are shown Field test. Field tests are con- in Figure 4. ducted with the instruments inIf all of the instruments had exstalled at an operating water or cellent field tests, there would be wastewater treatment plant for little need to perform the bench periods of 45 to 90 days. Those tests. However, very few instruparameters that were controlled ments have perfect conformance in the bench test a,'e monitored results during the field test. The during the field test. The purpose results of the bench tests have of the field test is to ascertain in- been extremely useful in interprestrument performance and mainting the results of the field test. tenance r e q u i r e m e n t s u n d e r General analysis of design. The typical field conditions where many environmental factors are general analysis of design atchanging at the same time. Con- tempts to address design features formance tests are conducted that cannot, in all cases, be quantitwice daily and consist of compar- fied by test procedures and tabuing the instrument output to labo- lar data, yet are often directly ratory values. Repairs and related to the success or failure of calibrations are based upon the the instrument. This information conformance tests and are sum- is de~.-~vedduring the bench and marized in the final report. field tests and from an examinaResponse times and output tion of the instrument documentanoise are measured at the begin- tion. A partial list of the typical ning and end of the field test. general analysis of design features These tests differ from the corre- are shown in Figure 5. VOLUME 31 o NUMBER 1 o 1992

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WATERAND WASTEWATERTREATMENTINSTRUMENTATION

Test Report

IBOARD OF DIRECTORS]

The test report contains results from all of the bench and field tests, the general analysis of design, and u n e d i t e d c o m m e n t s from the manufacturer of each instrument. Unlike Consumer Reports, h o w e v e r , ITA does not attempt to rank the different instruments or make recommendations on which instruments to purchase. This decision greatly depends on the specific application and varies significantly between sites. In monitoring applications, for instance, low noise and low drift may be of prime importance while response time is relatively unimportant. For control applications, however, a fast response time may be the most critical feature. Help in interpreting the test results is available from individual ITA members.

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DRAFTS PROTOCOL

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REVIEWS PROTOCOL

ITECHNICAL COMMITTEE~

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Clearinghouse Service

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Figure 1-Development of Test Protocols

Although instrument test reports are an important product from ITA, the association realized that it would never be able to test a sufficient n u m b e r of instruments to satisfy the needs of all its members. Therefore, ITA created its instrumentation clearinghouse service.

Help in interpreting the test results is available from individual ITA members.

I

I TEST PROTOCOL i

BENCH TEST

FIELD TEST

GENERAL ANALYSIS OF DESIGN

(Controlled Conditions)

(45 to 90 Doys)

(Subjective Anolysis)

Figure 2~Test Protocol

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ISA TRANSACTIONS

THE INSTRUMENTATION TESTING ASSOCIATION

I BENCH TEST 1 |

POWER SUPPLY

ELECTRONICS

WET TESTS

SS Supply Voltage Transient Overvoltage Transient Supply Voltage Supply Voltage Depression Short Term Interruption Supply Frequency Effects Harmonic Distortion Effects

Output Load Effects Zero & Span Rangebility Cow.non Mode Interference Normal Mode Interference Output Signal Ripple Signal Terminal Grounding Worm-Up Effects Ambient Temp. Effects

Drift Test Calibration Measured Accuracy Linearity Hysteresis + Dead Band

Dead Band Repeatability Reproducibility Ranging Effects Response Time Interferences Flow Sensitivity Sample Temp. Effects

FIGure3-Typical Bench Tests

J FIELD TEST / RESPONSE TIME At Installation After Completion

REFERENCE MEASUREMENTS Twice/Working

Day

I

OUTPUT NOISE

DOCUMENT MAINTENANCE REQUIREMENTS

Fast Somp',ing

Routine Breokdown

60 or 90 Doys

Figure a-Typical Field Tests The c!earinghouse is a computer data base of instrumentation at approximately 100 sites. Each record includes the type of instrument, the manufacturer, the model number, the number of instruments in ~ervice, the length of service, and a contact person and telephone number. The clearinghouse can be used in a n u m b e r of ways. The most

common request is that a member wants information on a specific b r a n d or model of instrument. The data base is searched for that specific instrument and reports list of sites that use it. The member can then directly write or phone a contact person with experience on that instrument. Some agencies may also have internal test results they will share.

Monthly Newsletterand Special Bulletins [TA mails a monthly newsletter to its members. The newsletter contains current information of interest to ITA's members such as a n n o u n c e m e n t s of u p c o m i n g events, status of ongoing projects, and surveys for determining fub.~re projects. Potential members VOLUME 31 . NUMBER 1 ® 1992

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WATER AND WASTEWATERTREATMENTINSTRUMENTATION

GENERAL ANALYSIS OF DESIGN Principles of Operation Operating Characteristics Maintenance Characteristics Quality of Construction System

Support

Commissioning

Requirements

Policies of Manufacturer Licensing and Permits Figure 5-General Analysisof Design can receive several months of the newsletter for free by requesting it from the national office.

The first ITA-sponsored workshop was a two-day event on Flow Measurement. The workshop included over fifteen experts discussing all aspects of flow measurement. Topics included regulatory agency programs, flow measurement fundamentals, selecting and specifying flowmeters, verifying accuracy, and monitoring ~erformance. The Flow Meat 08

ISA TRANSACTIONS

ITA is a contributing member to the National Institute of Standards and Technology (formerly the National Bureau of Standards) in a joint research program to characterize the effects of nonideal installation on flowmeters. NIST examined velocity profiles in a pipe downstream of common piping obstructions such as a single 90 degree elbow and (the dreaded) two elbows in a double plane configuration. The researchers at NIST used the velocity profiles to derive a d i m e n s i o n l e s s swirl number, which characterized the flow at different distances downstream of the obstruction. The swirl number in conjunction with a magnetic f l o w m e t e r was used to estimate the true flow rate to a very high degree of precision. Work on different types of obstructions and flowmeters is continuing.

BiannualMeetings surement w o r k s h o p was presented at four different locations including Burlington, Ontario (September 1989), Philadel-

Each annual meeting also includes a technical program. Sponsoringof Instrumentationand Control Workshops

Sponsoringof Instrumentation Research

phia, Pennsylvania (April 1990), Chicago, Illinois (July 1990), and Sacramento, California (May 1991). ITA is presently organizing a two-day Instrumentation and Control Workshop with an emphasis on instrument maintenance. This workshop is planned to coincide with ITA's Annual Meeting in April 1992 in Louisville, Kentucky.

ITA holds biannual meetings in A p r i l / M a y and in October (in conjunction with the Water Pollution Control Federation annual conference). The spring meeting has a larger technical program is officially recognized as the Annual Meeting. The Technical C o m m i t t e e s o m e t i m e s meets again in January. 1hese meetings provide a forum where members can interact, share ideas and information, and formulate new strategies for the organization. All of the ITA committees meet during the biannual meetings to prese~t results, make technical decisions and policy recommendations, and brainstorm new ideas. The committee meetings are characterized by free exchanges of ideas, data, and opinions. The Board of Directors meets after the committee meetings to review the

THE INSTRUMENTATION TESTING ASSOCIATION

budget and make policy deci- MiscellaneousTechnicalServices (i.e., Parshall flumes, vorsions. An ITA business meeting is tex shedding, weirs, etc.), appropriate applications, usually held after these meetings. ITA also performs many misand a checklist to deterProgress of the organization is cellaneous technical services for mine whether your applidiscussed and ITA officials are its members: cation is appropriate for elected. (1) Many member organizathese flowmeters. Each annual meeting also intions are willing to share cludes a technical program. In the internal test results. Although some of these tests past, the technical program has inare not as general or rigor- SUMMARY cluded presentation of prelimious as ITA's normal test, nary results from instrument tests, they still hold valuable inThe Water and Wastewater Inspeakers from the National Instiformation for users. strumentation Testing Associatute of Standards and Technology tion of North America (ITA) is a (2) The Technical Committee (formerly the National Bureau of corporation will develop, help develop, not-for-profit Standards) discussing installation founded in 1984 and dedicated to or review in-house test effects on flowmeters, and naimproving the performance and protocols for member orgational experts discussing direcreliability of instrumentation used nizations. in the water and wastewater intions in c h l o r i n a t i o n and The Technical Committee (3) dustries. ITA conducts evaluadechlorination. The 1991 annual has developed a series of tions of instruments, maintains an meeting includes a half day workdesigner check lists for instrumentation data base, pubshop on the use of programmable flowmeter applications. lishes a newsletter and special logic controllers (PLCs) in water Each bulletin discusses the bulletins, conducts workshops and wastewater along with a PLC particular type of flow- and seminars, and holds biannual meter technology meetings. equipment show.

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