Document JJQVjzO6Jy46VZ9Do89daL6y2

' 1016 CHAPTER 49 1950 Guide subject is now under investigation by the A.S.H.V.E. Research Laboratory. At the National Bureau of Standards a test method was developed for interested Government agencies, under which measured samples of the un cleaned air and of the air cleaned by a device under test are passed through filter papers.58 The ratio of the flow rates through the two filter papers is adjusted during successive tests, until the resulting dust spots approach equality in density as shown by a photometer. The ratio of the flow rates is then indicative of the effectiveness of the cleaner in arresting dust. A statement of an air cleaner's efficiency by any test method, is meaningless unless the test dust is specified. Other instruments for determining gaseous and particulate air con taminants are described in industrial hygiene literature.55 - 59 6061 Sound and Vibration Measurements Approximate measurements of sound intensity can be made by aural methods. The ear is used to compare the measured noise with sounds of known strength. Electrical devices, in which the ear plays no part, furnish the most satis factory-means of measuring noise intensities. The sound meter consists essentially of a microphone coupled to an amplifier designed with an ear-like response. The output of the microphone is read on a sensitive direct . current milliammeter graduated to read directly in decibels. Instruments of this type, if connected with suitable band pass filters, can be used to study the intensity of the sound over its entire range of frequencies. Electrical instruments are available for measuring the frequency, ampli tude and acceleration of a vibrating mass. They are usually more con venient and accurate than the vibrating reed tachometer, the seismic type displacement meters or the accelerometers which can also be used for this purpose. Sound level meters are discussed in several text books62-63 and standards.64 REFERENCES 1 Standard Code for Testing and Rating Steam Unit Heaters (A.S.H.V.E. Trans actions, Vol. 36,1930, p. 165), adopted January, 1930, by A.S.H.V.E. 2 A.S.H.V.E. Standard Code for Testing and Rating Steam Unit Ventilators (A.S.H.V.E. Transactions, Vol. 38,1932, p. 25), adopted June, 1932. A.S.R.E. Standard Methods of Rating and Testing Air Conditioning Equipment, A. S.R.E. Circular-No. 13. 4 A Survey of Testing Methods and Rating Limits for Domestic Heating Devices, by R. S. Dill (A.S.H.V.E. Transactions, Vol. 61, 1945, p. 185). For a comprehensive treatment of temperature measurement the reader is re ferred to Temperature, Its Measurement and Control in Science and' Industry, a symposium sponsored by the American Institute of Physics and published by Rein- hold Publishing Corp. . 4 Errors in the Measurement of the Temperature of Flue Gases, by P. Nicholls and W. E. Rice (A.S.H.V.E. Transactions, Vol. 35,1929, p. 473). 2 Temperature Measurement (A B.M.E. Power Test Code, Part 3). Investigation of Warm Air Furnaces and Heating Systems, by A. C. Willard, A. P. Kratz and V. S. Day (Illinois Engineering Experiment Station, Bulletin No. 120). Measuring Heat Transmission in Building Structures and a Heat Transmission Meter, by P. Nicholls (A.S.H.V.E. Transactions, Vol. 30,1924, p. 94). 10 Parallel-Connected Thermocouples for the Testing of Gas Appliances, by Walter B. Kirk and George J. Pacanovsky {Gas, September, 1939, p. 51). 11 American Standard for Indicating Pressure and Vacuum Gages, Round Dial Type, with Elastic Pressure Chamber, B. 40.1-1939 (American Standards Association), ' Instruments and Measurements 1017 u Standard Test Code for Centrifugal and Axial Fans, 1938 (AjSJLVJJ. and HAEMj Fan Engineering, Buffalo Forgo Company, 5th Edition, p. 165. - u Illinois Micrdmanometer (University of Illinois, Engineering Experiment Sta tion Bulletin No. 120, p. 91). The Weathertightness of Rolled Steel Windows, by J. E. Emswiler and W. C. Randall (A-S-H.V.E. Transactions, Vol. 34,1928, p. 527). w Pressure Measurement (AJ3MJB. Power Test Code 1936, Part 2, Chapter 2). The Measurement of Static Pressure, by C. J. Fechheimer, Mechanical Engineer ing, August, 1927. i* Psychrometric Tables for Vapor Pressure, Relative Humidity and Temperatures of the Dew-Point (If. S. Department of Agriculture, Weather Bureau, Washington, D. C.). i* For technical data refer to Fluid Meter Reports, Parts 1--1937, 2--1931, and 3-- 1933 (American Society of Mechanical Engineers). i Technical Notes No. 546 (National Advisory Committee for Aeronautics] Novem ber, 1935). 91 The Characteristics of Double Pitot Tubes, by F. R. Ingram, E. Diei-Canseco and L. Silverman (A.S.H.V.E. Journal Section, Heating, Piping and Air Condition ing, November, 1942, p. 708). 22 Discharge Coefficients of Square Edged Orifices for Measuring the Flow of Air, by H. S. Bean, E. Buckingham and P. S. Murphy (Bureau of Standards Journal of Research, Vol. 2, 1929, p; 561). - 22 Flow Measurement by Nozzles and Orifice Plates (AJS.M.E. Power Test Codes, Chapter 4 of Part 5, 1940). Air Flow Measurement in the Laboratory, by D. D. Wile, Refrigerating En gineering, June, 1947, p. 515. 22 A.S.H.V.E. Research Report No. 1204--Entrainment and Jet-Pump Action of Air Streams, by G. L. Tuve, G. B. Priester and D. K. Wright, Jr. (A.S.H.V.E. Trans actions, Vol. 48, 1942, p. 241). 22 A.S.H.V.E. Research Reports Nos. 857,911 and 966--Measurement of the Flow of Air Through Registers and Grilles, by L. E. Davies (A.S.H.V.E. Transactions. Vol. 36,1930, p. 201, Vol. 37,1931, p. 619, and Vol. 39,1933, p. 373). 17 A.S.H.V.E. Research Report No. 1162--Air Flow Measurements at Intake and Discharge Openings and Grilles, by G. L. Tuve and D. K. Wright, Jr. (AK.H.V.E. Transactions, Vol. 46,1940, p. 313). 33 A.S.H.V.E. Research Report No. 1092--The Flow, of Air Through Exhaust Grilles, by A. M. Greene, Jr. and M. H. Dean (AB.H.V.E. Transactions, Vol. 44. 1938, p. 387). * A.S.H.V.E. Research Report No. 936--Investigation of Air Outlets in Class Room Ventilation, by G. L. Larson, D. W. Nelson and R. W. Kubasta (A.S.H.V.E. Transactions, Vol. 38,1932, p. 463). 20A.S.H.V.E. Research Report No. 1076--Air Distribution From Side Wall Outlets, by D. W. Nelson and D. J. Stewart (A.S.H.V.E. Transactions, Vol. 44. 1938, p. 77). 21 Measuring Air Flow, by G. L. Tuve (Heating, Piping and Air Conditioning, December, 1941). 32 A.S.H.V.E. Research Report No. 1140--The Use of Air Velocity Meters, by G. L. Tuve, D. K. Wright, Jr. and L. J. Seigel (A.S.H.V.E. Transactions, Vol. 45, 1939, p. 645). 23 Temperature, Humidity and Air Motion Effects in Ventilation, by O. W. Armspach and Margaret Ingels (A.S.H.V.E. Transactions, Vol. 28,1922, p. 103). 24 A.S.H.V.E. Research Report No. 1165--Development of Instruments for the Study of Air Distribution in Rooms, by A. P. Kratz, A. E. Hershey and R. B. Engdahl (AB.H.V.E. Transactions, Vol. 46, 1940, p. 351). 22 Development of Testing Apparatus for Thermostats, by D. D. Wile (A.S.H.V.E. Transactions, Vol. 42,1936, p. 349). 22 The Heated Thermometer Anemometer, by C. P. Yaglou (Journal Industrial Hygiene and Toxicology, Vol. 20, October, 1938, No. 8). 23 A.S.H.V.E. Research Report No. 959--Indices of Air Change and Air Distribu tion, by F. C. Houghten and J. L. Blackshaw (A.S.H.V.E. Transactions, Vol. 39. 1933, p. 261). 22 The Temperature of Evaporation, by Willis H. Carrier (AE.H.V.E. Transac tions, Vol. 24, 1918, p. 25).