Document LKnwmjvaevVdam54QgjdZgqGz

192 CHAPTER 10 1949 Guifl! 10 The Volumetric Incidence of Atmospheric Allergens, II: Simultaneous Measure ments by .Volumetric and Gravity Slide Methods, by O. C. Durham (Journal 0i Allergy, Vol. IS, May, 1944, p. 226-235). '! " Air-Borne Fungus Spores as Allergens, O. C. Durham (Aerobiology, p. 32--47 Publication No. 17, American Association/or the Advancement of Science, Washington' D. C., 1942). ' 15 Sampling Devices, by H. G. DuBuy and A. Hollaender (American Journal of Medical Science, Vol. 209, February, 1945, pi 172-177). BIBLIOGRAPHY Abstracts and Bulletins (monthly, annual and special) Industrial Hygiene Founda tion, Inc., Pittsburgh, Pa. Aerobiology, Publication' No. 17 (American Association for the. Advancement of Science, Washington, D. C.; 1942). Air Sanitation and Industrial Ventilation, by W. N. Witheridge (Detroit, Mich 1945). Analytical Chemistry of Industrial Poisons, Hazards and Solvents, by M. B. Jacobs (Interscience Publishers, New York, 1941). letiBnibNloio.g2rSa9p, h1y91o5f).Industrial Hygiene, 1909-1943 (U. S. Public Health Service Bul Clouds and Smokes, by W. E. Gibbs (P. Blakiston's Son & Co., Philadelphia, Pa., 1924). Determination and Control of Industrial Dust, by Bloomfield and DallaValle (If. S. Public Health Service Bulletin No. 217, 1935). . Dust, by S. C. Blacktin (The Sherwood Press, Cleveland, 1934). Bos(Ttohne,)1E93n7v)i.ron.men.t an.d Its.Eff.ect .upon Man (Harvard School of Public Health, Industrial Dust, by Drinker and Hatch (McGraw Hill Book Co., New. York, 1936). Journal of Industrial Hygiene and Toxicology (monthly) (Harvard School of Public Health, Boston, Mass.). See cumulative abstract'and subject indexes. Manual of Industrial Hygiene, by W. M. Gafafer et al (U. S. Public Health Service, W. B. Saunders Co., Philadelphia, 1943). Noxious Gases and the Principles of Respiration Influencing their Action, by Hen derson and Haggard (American Chemical Society Monograph Series No. 35, Reinhold, New York, 1943). , Occupation and Health, two volumes (International Labor Office, Washington, D.C.). . . . i, ....... Toxicology and Hygiene of Industrial Solvents, by Lehmann and Flury, trans lated by Eleanor King and H. F. Smyth, Jr. (Williams and Wilkins, Baltimore, 1943). \ CHAPTER 11 INSTRUMENTS AND MEASUREMENTS Temperature Measurement, Pressure Measurement, Measurement of Air Movement, Air Change Measurements, Measurement of Relative Humidity, Dust Deter mination, Heat Transfer Through Building Materials, Measurement of Heat Exchange for Comfort Conditions, Combustion Analysis, Smoke Density Measurements, Sound and Vibration Measurements HEATING and air conditioning engineers and technicians require instruments for both laboratory and field use and somewhat more pre cision is attainable and essential in the laboratory, where research and de velopment are undertaken, than in the field, where acceptance and adjust ment tests are conducted. Some instruments have attained an adequate state of development while others fall far short of the desirable. For in stance temperatures can now be measured readily with ample accuracy for most purposes while a convenient and precise method for determining or comparing the dustiness of atmospheres is lacking and improvement in existing hygrometers and humidity controllers is essential. Codes and standards covering different types of heating and air condi tioning devices and apparatus have been promulgated by various authori tative organizations and instruments essential for performance or com pliance testing are enumerated in the relevant publications.1, *a' * The present purpose is to discuss the use and characteristics of the more im portant instruments. TEMPERATURE MEASUREMENT5,6 Thermometers Any device capable of indicating temperature'is a thermometer but in common usage the term thermometer without qualification has come to signify the ordinary mercury-in-glass temperature indicating device. This type has a useful range from --40 F, the freezing point of mercury, to about 1000 F, at or near which the glass usually softens. Lower temperatures can be measured with alcohol-filled thermometers for .which the range is about --94 F to +248 F. The better thermometers have their scales, either Fahrenheit or Centigrade, etched with acid into the glass which forms their stems. The probable error for etched stem thermometers is plus or minus one scale division, and calibration is desirable for much, test work. Thermometers are calibrated during manufacture at not less than two temperatures--the freezing and boiling points of water--and calibration is often accomplished with the instrument completely immersed in a bath at the known temperature. The intervening scale divisions are then ap plied to the stem. When such a thermometer is used with the stem in completely immersed, a correction known as the stem correction is neces sary for accurate measurements, and its magnitude is usually computed by means of the following formula: where K = 0.00009 D (t, - t,y (1) K = correction to be added,.Fahrenheit degrees. 193