Document dQD1e8vj8DLke8JNkBMNwMBOQ

626 __________._________ _____________________________ Chapter 34 1945 Guide ! impingement at high velocity under water, collection bn porous crucibles through which air passes, and electric precipitation. Determination may . be by direct weighing of samples or by microscopic counting. The most commonly used methods are the modified Hill dust counter using micro scopic count, the Smith-Greenburg impinger which' collects samples in water and which are counted under a microscope in a. Sedgwick'cell5*, and the Lewis84 sampling tube with the analytical determination of the increase in weight of a porous crucible. All reports should state the method of sampling and counting. The A.S.H.V.E. Code for Testing and Rating Air Cleaning Devices Used in General Ventilation Work specifies the porous crucible method85. HEAT TRANSFER THROUGH BUILDING MATERIALS The A.S.H.V.E. Standard Test Code for Heat Transmission Through Walls88 describes the construction and use of the guarded hot box for determining over-all heat transmission coefficients of built-up sections. In June, 1942, the A.S.H.V.E. adopted a standard test procedure for determining the conductivity of'materials by the use of a guarded hot plate87. The Nicholls heat meter is very useful for determining the heat flow through walls of buildings88. MEASUREMENT OF HEAT EXCHANGE FOR COMFORT CONDITIONS Several instruments have been devised to measure the effect of various factors as they relate to the comfort of the body89. The principal ones are . the Kata-thermdmeter, Dufton's eupatheoscope, Vernon's, globe ther mometer, Winslow and Greenburg's thermo-integrator, and Yaglou's heated globe40,41. These instruments were designed to obtain a quanti tative measurement of the thermal exchange between the human body and its environment. COMBUSTION ANALYSIS The analysis of flue gases to determine completeness and efficiency of combustion is usually made chemically with the Orsat apparatus: This consists of a measuring burette, a leveling bottle, and three pipettes. Carbon dioxide is absorbed in the first pipette by potassium hydroxide, oxygen in the second by potassium pyrogallate, and carbon monoxide in the third by cuprous chloride. A khown volume of gas is drawn in, and after each of the three absorptions the reduced volume is again measured in the burette. Pressure and temperature of the gas sample are kept npnblic Health Bulletin, No. 144, 1925, (U. S. Public Health Service). Testing and Rating of Air Cleaning Devices Used for General Ventilation Work, by S. R. Lewis (A.S.H.V.E. Transactions, VoI. 39,1933, p. 277). "A.S.H.V.B. Code for Testing and Rating Air Cleaning Devices Used.in General Ventilation Work, adopted Janaary, 1934 (A.S.H.V.E. Transactions, Vol. 39.1933. p. 225). "A.S.H.V.E. Standard Test Code for Heat Transmission Through Walls (A.S.H.V.E. Transactions. Vol. 34,1928, p. 253), adopted 1928. "Standard Method of Test for Thermal Conductivity of Materials by Means of the Guarded Hot Plate (Tentative), adopted July, 1942, by A.S.H.V.E. "A.S.H.V.E. Research Report No. 685--Measuring Heat Transmission in Building Structures and a Heat Transmission Meter, by P. Nicholls (A.S.H.VJ2. Transactions, Vol. 30, 1924, p. 65). "Measurement of the Physical Properties of the Thermal Environment, by D. W. Nelson. F. R. Bichowsky, L. M. K. Boelter, R. S. Dill, A. P. Gagge, John A. Goff, A. E. Hershey. F. C. McIntosh, F. W. Reichelderfer.G. L. Ttrveand C. P. Yaglou (A.S.H.V.E. Journal Section, Heating, Piping and Air Conditioning, June. 1942. p. 382). "Instruments and Methods for Recording Thermal Factors Affecting Human Comfort, by C. P. Yaglou, A. P. Kratz and C--E. A. Winslow (Year Book, American Journal Public Health, 36-37). "The Thermo-Integrator--A New Instrument for the Observation of Thermal Interchanges, by C.-E. A. Winslow and Leonard Greenburg (A.S.H.V.E. Transactions, Vol. 41.1935, p. 149). Instruments and. Test Methods Number of Card i 2 3 4 Table 1, Ringelmann Smoke Chart Spacings Thickness of Lines, mm . 1.0 2.3 3.7 5.5. Distance in Clear Between Lines, mm 9.0 7.7 6.3 4.5 6%7 constant while measuring. Several passes are made through each .pipette which contains tubes dr glass beads to increase the wetted surface. It is essential that each reaction be completed before the next reaction is started. Since the life of the reagents is limited, it iswell'to keep a record ' of the number of samples tested. Care is needed in operation to prevent the pulling of reagents out of the pipettes int& the capillary tubing and burette. Many recording gas analyzers are available and are usually found in the larger plants. Carbon Monoxide Measurement A method of analyzing for low carbon monoxide concentrations com pletes the oxidation of the carbon monoxide in a known volume of sample, in the presence of a catalyst. The heat resulting is measured by a thermocouple calibrated in parts per 10,000 of carbon monoxide42. oiqval UBnau I N&ASUKLMCn iS 'Smoke density may be judged by assigning to it the number of the Ringelmann Smoke. Chart which appears to have the same color when observed at a distance of 50 ft. The charts are numbered 1 to 4 and are made of black lines cross-ruled on .white as given in Table L , Apparatus using the photo-electric cell has been devised for recordingsmoke densities in large plants. <Sart>on Monoxide Recorder, by S. H. Katz, D. A. Reynolds, H. W. Frevert aid J. J. Bloomfield yU. S. Bureau of Mines, Technical Paper No. 355,-1926). j.TMTMTM