Document 5Da9ZVM3J93ww2EoJkdOD77Qe

1150 CHAPTER 52 1955 Guide Table 1. Ringelmann Smoke Chart Spacings Number of Card Thickness op Lines, mm Distance in Clear Between Lines, mu i 1.0 2 2.3 3 3.7 4 5.5 9.0 7.7 6.3 4.5 (Subject 296), March 1934 and subsequent revisions, shall not reduce the output of a standard photoelectric cell from 9 microamperes, with a clear smoke pipe, to less than 8 microamperes." The Commercial Standard also requires that during a test after installation, the burner shall operate with out visible smoke at the chimney top. A method of evaluating smoke produced by pot type oil burners was developed for the Institute of Cooking and Heating Appliance Manufac turers by R. N. St. John. A glass rod is interposed between a light'source and a photo-sensitive cell, both before and after being exposed to the flue gases from a heating device. The diminution of the light transmitted by the rod, due to the deposit of soot on its surface, causes a reduction in the cell emf which is taken as an index of the concentration of smoke in the flue gases. A description of the method is contained in National Bureau of Standards Commercial Standard CS104-46.61 DETERMINATION OF AIR CONTAMINANTS Two measures of air dustiness are in use: particles per unit volunie of air, and weight per unit volume of air. A comparative method consists in drawing known samples of air through a known area of filter cloth or paper, and comparing the density of the resulting spots with blackness charts or with spots from other sources. For counting, particles are captured in a device such as the SmithGreenburg impinger, the Owens jet dust counter, or in an electrostatic or a thermal precipitation device designed for the purpose.66 Counting is done with a microscope, and the method yields important results when the nature or constituents of the dust are of interest. For a weight determination, a known volume of air is drawn through a porous crucible or thimble, and the weight gained by the thimble during the operation is the weight of the dust captured from the air sample.67 For precise work, the thimble must be dried in a desiccating chamber before weighing each time. The test method specified in the A.S.H.V.E. Code for Testing and Rating Air Cleaning Devices Used in General Ventilating Work is based on a weight method for evaluating the cleanliness of air after pass ing through an air cleaner.68 The Code has not filled all needs for an air cleaner testing method and the 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.65 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 Instruments and Measurements 1151 and particulate air contaminants are described in industrial hygiene litera ture.66-"61 62 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 books63-64 and standards.66 REFERENCES `Standard Code for Testing and Rating Steam Unjt Heaters (adopted jointly by The American Society of Heating and Ventilating Engineers and the Industrial Unit Heater Association, January 1950, second edition). ,, .3 A.S.H.V.E. Standard Code for Testing and Rating Steam Unit Ventilators (A.S.H.V.E. Transactions 'oh 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. Survey of Testing Methods and Rating Limits for Domestic Heating Devices, by R. S. Dill (A.S.H.V.E. Transactions, Vol. 51, 1945, p. 185). i For a comprehensive treatment of temperature measurement the reader is referred to Temperature, Its Measurement and Control in Science and Industry, a symposium sponsored by the American Institute of I nysta and published by Reinhold Publishing Corp. ` Errors in tbe Measurement of the Temperature of Flue Cases, by P. Nicholls and W. E. Rice (A.S.H.V.E. 1 hansactjons, Vol. 35, 1929, p. 473). '.Temperature Measurement (A.S.M.B. "Power Test Code. Part 3). iv * I/J'j^t'Sfction of Warm Air Furnaces and Heating Systems, by A. C. WiUard,-A. P. KraU and V. S. * *y (iffmom Engineering Experiment Station, Bulletin No. 120). / Meat Transmission in Building Structures and a Heat Transmission Meter, by P. Nicholls (A.b.H.V.E. Transactions. Vol. 30, 1924. p. 94). l Parallel-Connected Thermocouples for tbe Testing of Gas Appliances, by Walter B. Kirk and George - Pacanovsky (Gas, September, 1939, p. 51). ` _ ,I;VnerjCan Standard for Indicating Pressure and Vacuum Gages, Round Dial Type, with Elastic Pres sure Chamber, B. 40.1 1939- American Standards Association). v 4,Jtfn^ar^1 Test Code for Centrifugal and Axial Fans, 1938 (A.S.H. VJS. and N.A.F.M.) published by *.A.*.M. aa Bulletin No. 110. Fan Engineering, Buffalo Forge Company, 5th Edition, p. 165. Illinois Micromanometer {University of Illinois,'Engineering Experiment Station Bulletin No. 120, p. 91). 'rB, Jhe ^^thertightness of Rolled Steel Windows, by J. E. Emswiler and W. C. Randall (A.S.H.V.E. transactions, Vol. 34, 1928, p. 527). . !! ressure Measurement (A.S.M.B. Power Test Code 1936, Part 2, Chapter 2). u ^^Rsnrement of Static Pressure, by C. J. Fechbeimer (Mechanical Engineering, August, 1927). (1/ c gi^--r.metr*c Tables for Vapor Pressure, Relative Humidity and Temperatures of the Dew-Point `lf * ePQriment of Agriculture, Weather Bureau, Washington. D. C.), ^ata^re(er to Fluid Meter Reports, Parts 1--1937, 2--1931, and 3--1933 (American Society j, ^c^n*cal Notes No. 546 (National Advisory Committee for Aeronautics, November, 1935). (A.S H v p^Tracter*sti? * double Pitot Tubes, by F. R. Ingram, E. Dies-Canseco and L. Silverman ` * ' journal Section, Heating, Piping and Air Conditioning, November, 1942, p. 708). ;nehflm*of Square Edged Orifices for Measuring the Flow of Air, by H. S. Bean, E. Bucka p. ** v * Murphy (Bureau of Standards Journal of Research, Vol. 2, 1929, p. 561). (940). W Measurement by Nowles and Orifice Plates (A.S.M.B. Power Test Codes. Chapter 4 of Part 5, }J Measurement in the Laboratory, by D, D. Wile (Refrigerating Engineering, June, 1947, p. 515). Tuve r. Research Report No. 1204--Entrainment and Jet-Purbp Action of Air Streams, by G. L. * a. Pnester and D. K. Wright. Jr. (A.S.H.V.E. Transactions. Vol. 48, 1942, p. 241).