LETTERS Air monitoring networks Dear Sir: I have just finished the excellent article on Air Monitoring Networks (€S&T, June 1977, pp 544-549). Unfortunately, the article leaves the reader with the impression that there are only three domestic and one international firms seriously engaged in the construction of network systems. I wish to point out that Monitor Labs has built eighteen (18) telemetry network systems. Installations include: California Air Resources Board statewide network. Department of Public Health, Commonwealth of Massachusetts. Georgia Power Company, Atlanta, Georgia. State of Victoria, Melbourne, Victoria, Australia. Department of Environment, State of Washington. Department of Environmental Quality, State of Wisconsin. Each of these networks consists of more than ten (10) remote sites with air quality and meteorological sensors telemetered to a central site with a computer
Bendix." has been added. We are very puzzled about this because these instruments were in fact supplied by Philips. A. S. Lodder N.V. Philips Gloeilampenfabrieken Eindhoven, The Netherlands
to control telemetry, validate the data, and perform data reduction. With our System 7000 measurement system and System 5000 ADAM network software, we offer a complete package with most of the equipment of our own manufacture. The major distinction between Monitor Labs and others in the field is that we specialize in hardware and computer software, leaving the data interpretation to the consultants. Allan L. Budd Vice President, Marketing Monitor Labs, Inc. San Diego, Calif. 92121
More on air monitoring networks Dear Sir: I was delighted to see your June issue with the article on building air monitoring networks. I noticed in the article errors that are rather important from our point of view. At the top of page 548 column 3, the figure for the total number of people employed in Philips should be of course 400 000. In the same column, paragraph 4, the sentence "The NO, NOn, and O3instruments were purchased from
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Environmental Science & Technology
Also In the air monitoring business Dear Sir: We would like to call readership attention to another company in the business of designing, constructing, installing and operating air monitoring networks (see €S&T Special Report, Building Air Monitoring Networks, June 1977, p 544). The Environmental Systems Division of Xonics, Inc., based in Van Nuys, California, recently secured the EPA contract for data management and collection, and operation of the entire CHAMP network, having a cumulative value of approximately $5 million. Prior to this award, Xonics designed and delivered the air quality instrumentation systems under subcontract to Rockwell for use in the EPA-funded CHAMP and RAMS programs. Xonics' portion of the total contracts amounted to approximately $2.5 million. Xonics also is delivering air and water-quality monitoring systems under contract with the US. Army. Value of these orders exceeds $4 million. And, on the international scene, Xonics has delivered about $400 000 worth of monitoring equipment overseas, and has recently booked an additional $500 000. Xonics' engineering innovations led to many system hardware improvements, now considered standard practice in the industry, such as automatic dynamic gas calibration, accurate data conditioning, logging, integration, and display of air quality parameters, centralized ambient air-processing equipment, accurate temperature control of sensitive calibration components, meteorological monitoring equipment, and many others. Daniel L. Esau Director of Marketing
Air monitoring networks (cont.) Dear Sir: I was disappointedto see that the special report on air pollution monitoring (€S&T, June 1977, p 544) gave the impression that there are only three major companies providing total contractor services in the building and operation of air pollution monitoring networks (p 545, COI. 3). The facts are that several other companies are major factors in this field. Enviroplan, for example, has designed, installed, and has been operating air pollution and meteorological monitoring networks at more than forty site locations for several of our more than forty-five government and industrial clients. It is precisely because there now are a substantial and growing number of experienced and qualified companies providing these monitoring services that the electric
utility, industrial, and government customers for these services have benefited in terms of improved quality of the monitoring data, increased percentages of valid data collection, and a host of other specialized monitoring program services provided at the minimum possible cost. Howard M. Ellis, Presldent Enviroplan, Inc. Rutherford, N.J. 07070
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Water monitoring Dear Sir: We just completed a multiclient study, “Instrumentation and Process Control for Analysis and Control of Water Quality”. We forecasted that the markets for instrumentation and process control systems for the analysis and control of water quality will total over $4 billion during the 1976-85 period. The forecasts were made for (1) analytical instruments, (2)conventional instruments and control systems, (3) final control devices, and (4) computers and telemetry. In addition, markets were forecasted for various individual analytical and specialty instruments, as well as for other product categories. Seven market sectors relating to water quality were evaluated and market projections were made for each sector. These included: (1) municipal water treatment, (2) municipal water distribution, (3) industrial water treatment, (4) municipal wastewater collection, (5)industrial wastewater treatment, (6) municipal wastewater treatment, and (7) water quality monitoring. The markets for the various instruments and process control systems will vary, but will average about 11YOI y during the 1976-85 period. In addition to the above study, we conducted a multiclient study entitled, “Industrial Water Pollution Control-US. Markets and Technology,” last year. The price of the instrument study is $1200 per client. Robert E. De La Rue, President Robert E. De La Rue Associates
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Santa Clara, Calif. 95051 Opacity correction Dear Sir: I would like to correct one of the sketches used to illustrate the feature, “Clearing the Opacity Issue” (€S&T, June 1977, pp 561-563) in order to clear up any confusion. The caption under the sketch labeled Altitude states, “Due to sunlight scattering, visual opacity increases as the sun’s altitude increases. In summer, the altitude of the sun at noon is 79’; in winter, 33’; spring 56’ and fall 34’.” The last clause is in error, the altitude of the sun at noon in the fall (at the autumnal equinox) is not 34’. In the caption I submitted I stated “In spring and fall, the sun’s altitude at noon is 56’ at 34’ North Latitude.“Therefore, in the sketch itself, the label “fall” should not have been attached to “winter sun” but to the “spring sun.” The relationship of the sun’s altitude to opacity is quite significant. A perfect observer who read 56% opacity at noon in winter, would read 75% opacity in Volume 11, Number 9, September 1977
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