INSTRUMENTATION Michigan Symposium on Instrumentation for Industrial Hygiene included technical papers, reviews, exhibits, demonstrations
by Ralph H. TVTOT very long ago, the word " i n s t r u m e n t a t i o n " was more t h a n likely to suggest t h e New York Philharmonic or the Boston S y m p h o n y Orchestra even to scientists and technologists. Since i n s t r u m e n t a t i o n has become recognized as a distinct branch of b o t h science a n d technology, it has even acquired special emphasis in a variety of fields. So wide a n d extensive is this b r a n c h of knowledge t h a t one n o t infrequently encounters i n s t r u m e n t symposia devoted to a special field of science. Instrumentation for Industrial Hygiene W e participated recently in a S y m posium on I n s t r u m e n t a t i o n for I n dustrial Hygiene a t t h e School of P u b lie H e a l t h of the University of Michigan, u n d e r t h e sponsorship of the University's I n s t i t u t e of I n d u s t r i a l Health a n d School of Public H e a l t h a n d some nine cooperating agencies in t h e field of public health, industrial health, and i n s t r u m e n t a t i o n . This symposium h a d four distinct objectives: (1) t o bring together i n s t r u m e n t m a k e r s a n d users of i n s t r u m e n t s in t h e field of industrial hygiene; (2) to m a k e k n o w n w h a t is needed a n d w h a t is available; (3) to exhibit home-assembled devices a n d t o exchange information a n d ideas on e q u i p m e n t and (4) t o g a t h e r material for a n Encyclopedia for I n s t r u m e n t a tion for I n d u s t r i a l Hygiene. All sessions a n d exhibits were held in the stately and impressive halls a n d chambers of t h e H o r a c e R a c k h a m Building from M a y 24 to 27. A series of general sessions was devoted to comprehensive review addresses. I n addition, there were technical sessions a n d papers devoted t o specific t y p e s of i n s t r u m e n t a t i o n . T h e VOLUME
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emphasis t h r o u g h o u t was on instrum e n t a t i o n r a t h e r t h a n a compilation of d a t a obtained with i n s t r u m e n t s . Nearly 100 i n s t r u m e n t manufacturers were represented in well chosen exhibits. I n addition, nearly 100 homeassembled i n s t r u m e n t s were exhibited b y some 25 individuals, companies, universities, or research agencies. T h e s e represented instrumental developments for special problems, and, in most cases, were devices for which no a p p r o priate i n s t r u m e n t is commercially available. I n our opinion, t h e value of such exhibits a n d demonstrations is becoming appreciated more and more b y t h e scientific public. I t has been a n old a n d well established practice a t national meetings of t h e American M e d i cal Association and a similar, t h o u g h more extensive, exhibit a t t h e D y s o n Perrins L a b o r a t o r y in Oxford was one of t h e o u t s t a n d i n g features of t h e 1952 I n t e r n a t i o n a l Congress of Analytical Chemistry. T h e preparation of t h e encyclopedia is now u n d e r way. T h i s will include n o t only all t h e papers presented a t t h e symposium, b u t descriptions a n d illustrations. of all i n s t r u m e n t s which were exhibited. I t is likely t h a t some of the papers will also a p p e a r in various scientific journals. T h e subjects discussed a t the symposium were, almost w i t h o u t exception, of direct interest to the analytical chemist. I n m a n y respects, it m a y be said t h a t industrial hygiene is largely concerned with the analysis of toxic or h a z a r d o u s materials. T h e r e are cert a i n features which are more particularly significant to t h e industrial hygienist. A u t o m a t i c recording, the initiation of alarms, or actual control of environm e n t a l conditions such as ventilation
Müller
is more i m p o r t a n t t h a n it would be for t h e average analyst. Some problems, such as propei' illumination or noise levels, are obviously of more interest to t h e physicist. Topics
Discussed
F o r the present, it m a y be helpful to list the topics which were discussed, because it m a y require something of the order of a year before t h e papers are published or collected u l t i m a t e l y in t h e encyclopedia. T h e review addresses were as follows: Concepts and Purposes of the Symposium. William G. Frederick. Sampling and Analyzing Air for Contaminants in Work Places. Leslie Silverman. Laboratory Type Instrument of Specific Application to Industrial Hygiene. Hervey B. Elkins. Instruments for Measuring Air Velocity and Metering Air. Knowlton J. Caplan. Instruments for Measuring Sound and Vibration. Charles R. Williams. Instruments Specifically Designed for Atmospheric Pollution Evaluation. George D. Clayton. Home-Assembled Instruments. Warren A. Cook. Instruments for Measuring Ionizing Radiations. Karl Z. Morgan. Instruments for Measuring Ultraviolet, Visible, and Infrared Energy. Hugh Archer. T h e technical papers included : Instruments for Sampling and Analyzing Organic Vapors in Air. Ε. Μ. Adams. Developments in the Sampling of AirBorne Dust. Theodore F. Hatch. The Calibration of Gas, Vapor, and Dust Instruments. Their Accuracy and Sensitivity. E. W. Gilliland. Elcctrometric Instruments. Philip J. Elving. 37 A
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I t was amply evident from this meet ing t h a t t h e subject requires t h e com bined talents of the physician, t h e in dustrial engineer, t h e analytical chem ist, t h e toxicologist, and t h e instrument designer. "While all b u t t h e latter are required to define the problem, it is largely the responsibility of t h e instru m e n t designer to provide equipment which will maintain a safe, healthy, and efficient environment for t h e worker in industry. W h e n equipment can be designed which records t h e concentration of a given hazardous substance, and which also has t h e means for controlling or correcting t h e conditions t h a t give rise to t h e hazard, we have t h e beginning of completely automatic correction. I t is obvious t h a t one cannot a t t a i n complete security unless t h e system also includes periodic self-calibration and "fail-safe" features.
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Instrumentation for Particle Sizing. Melvin W. First. Absorption and Emission Spectroscopy. E. J. Rosenbaum. Meteorological Measurements in Air Pollution Studies. E. Wendell Hewson. Filter Collecting Media. Leslie A. Chambers. Application of Electronics to HomeMade Instruments. An Elementary Treatment. Ralph H. Millier. The Construction of Automatic Con tinuous and Intermittent Sampling De vices. William L. Wilson. T h e Calibration of Airflow Measuring Instruments. George M. Hama. Devices for Stack Sampling and the Measurement of Air Velocities in Stacks. Richard B. Engdahl. Vibration Measuring Instruments and Their Application to Noise Control. H. C. Hardy. Intermittent Sound Measurement. A Challenge. H. H. Scott. Alpha Hazard Monitoring Instruments. Duncan A. Holaday. Calibration of Instruments for Measur ing Ionizing Radiation. Harold O. Wyckoff. Infrared Measurement. W. G. Hazard. Ultraviolet Measurement. Rudolph Nagy. T h e Measurement of Light. W. Glenn Pracejus.
Today, one hears a great deal a b o u t automation. Apparently, this is in tended to apply to t h e s t a t e of affairs in which instrumentation is carried t o its logical conclusion. Conditions are not merely measured b y instruments, b u t t h e o u t p u t of t h e latter is used t o control a process. I t is a complete closed-loop servo-system in which de finitive instructions are supplied to t h e machine, b y manual dial settings, or b y punched card, or b y tape-recorded ANALYTICAL
CHEMISTRY
INSTRUMENTATION instructions. From the analytical standpoint, if chemical analysis of the product is proceeding continuously, and at high speed, and if these results are used to control all process varia bles, we have complete automation. As we have remarked frequently, there is no need or place for statistical quality control in such cases. Sta tistical considerations appeal principally to the legal, business, or administra tive mind. Obviously, our present practices of grab or sample analysis require statistical treatment, but until instrumental inspection of the complete output is attained, we shall have to be addicted to these practices. In a recent discussion on sampling, our good friend Beverly Clarke made the humorous and shrewd observation that 100% sampling is the ideal. Per haps his audience was a bit too willing to accept the belief that one must settle for a much smaller sample. In these days, when more and more measure ments of high precision are being made in microsecond intervals, the possibility of analyzing the entire output becomes increasingly likely. One rapidly ap proaches that feeling of security expressed by Mark Twain's "Christian faith and four aces." Although statistical con siderations are becoming increasingly popular, there are some very funda mental and serious doubts being raised against their indiscriminate use. Ein stein has become increasingly worried about probability considerations and has expressed the uncomfortable feeling in the hunch that "God does not roll dice."
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Interpretation There is no denying the fact that inter pretation becomes increasingly difficult as information becomes more meager. There was a time when the manufacture of carbon granules for use in telephone transmitters was so poorly understood that very thorough and profound sta tistical studies were involved in order to maintain reasonable produ ction. Those studies were justifiably famous, but they became less and less important as extensive research into the nature of the carbonization process was made. A crude analogy to what we are discuss ing is afforded by the field of high-speed computing. An analog computer pos sesses whatever precision we build into its components. A digital computer, which does nothing but counting,fhas absolute precision. VOLUME
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