Document MM9Kv146631RnV7Jy3bk0a68a

HEATINC VENTILATING AIR CONDITIONING GUIDE 1940 oxygen in the second by potassium pyrogaliate, and carbon monoxide in the third by cuprous chloride. A known 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 constant while measuring. Several passes are made through each pipette which contains tubes or 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 is well 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 into the capillary tubing and burette. Many recording gas analyzers are available and are usually found in the larger plants. SMOKE DENSITY MEASUREMENTS A common method of determining the relative density of smoke issuing from chimneys is by visual comparison with the Ringelmann Smoke Charts. A sheet of four ruled charts with varying weights of black lines is used. The sheet is 12 by 26 in. over all on which are four charts, each consisting of 294 squares, 14 wide and 21 high. The width of line and spacings is given in Table 1. Table 1. Ringelmann Smoke Chart Spacings Number op Caro i 2 3 4 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 The charts are placed 50. ft from the observer and in line with the stack to be observed. At this distance the lines disappear, and the charts appear as varying shades of gray. At times a white chart is added as No. 0 to the left of the four charts 1 to 4, and a black chart to the right as No. 5. . Apparatus using the photo-electric cell has been devised for recording smoke densities in large plants. CARBON MONOXIDE MEASUREMENT In garages and vehicular tunnels carbon monoxide is a constant potential danger. In small amounts it causes headaches and inefficiency, and in larger concentrations it causes collapse and death in rather short periods of exposure. A method of analyzing for carbon monoxide con centrations completes 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 monoxide*7. Carbon Monoxide Recorder, by S. H, Katz, D. A, Reynolds, H. W. Frevert and J. J. Bloomfield (U. S. Bureau of Mines, Technical Paper No. 355, 1926). 774 Chapter 46 TERMINOLOGY Glossary of Physical and Heating, Ventilating and Air Conditioning Terms Used in the Text, Standard Abbreviations, Conversion Equations, Drafting Symbols, A.S.H. V.E. Codes Absolute Humidity: See Humidity. Absolute Pressure: The sum, at any particular time, of the gage pressure and the atmospheric pressure. Absolute Temperature: The temperature of a substance measured above absolute zero. Absolute Zero: The temperature (--459.6 F) at which the molecular motion of a substance theoretically ceases. This is the temperature at which the substance theo retically contains no heat energy. Acceleration: The rate of change of velocity. In the fps system this is expressed in units of one foot per second per second. V al Acceleration Due to Gravity: The rate of gain in velocity of a freely falling body, the-value of which varies with latitude and elevation. The international gravity standard has the value of 980.665 cm per second squared or 32.174 ft per second per second, which is the actual value of this acceleration at sea level and about 45 deg latitude. Adiabatic: An adjective pertaining to or designating variations in volume or pressure not accompanied by gain or loss of heat. When a substance undergoes adiabatic ex pansion, since it does not receive heat from without, the work which it does is at the expense of its internal energy, and therefore its temperature falls; similarly, when it is adiabatically compressed its temperature rises. Air Cleaner: A device designed for the purpose of removing air-borne impurities such as dusts, fumes and smokes. (Air cleaners include air washers and air filters.) Air Conditioning: A process by which simultaneously the temperature, moisture content, movement and quality of the air in enclosed spaces intended for human occu pancy may be maintained within required limits. Air Washer: An enclosure in which air is forced through, a spray of water in order to cleanse, humidify, or dehumidify the air. : Anemometer: An instrument for measuring the velocity of moving air. Atmospheric Pressure: The pressure exerted by the atmosphere in all directions; as indicated by a barometer. Standard atmospheric pressure is considered to be 14.7 lb per square inch, which is equivalent to 29.92 in. of mercury. Baffle: A plate or wall for deflecting gases or fluids. Blast: This word was formerly used to denote forced air circulation, particularly in connection with central fan systems using steam or hot water as the heating medium. As applied in this sense, the word blast is now obsolete. Boiler: A closed vessel in which steam is generated or in which water is heated. Boiler Heating Surface: That portion of the surface of the heat-transfer apparatus in contact with the fluid being heated on one side and the gas or refractory being cooled on the other, in which the fluid being heated forms part of the circulating system; this surface shall be measured on the side receiving heat. This includes the boiler, water walls, water screens, and water floor. (A.S.M.E. Power Test Codes, Series 1929.) 775