. Transactions. of greatest contraction xd, produces a static pres- G2G MEASUREMENT OF BLAST-FURNACE GAS sure Pi lower than p. In other words, a certain proportion of the initialpressure p is converted into velocity pressure due to the constrictionintroduced in the gas main. The formula that has been developed is as simple and reliable as neces-sary for determining the flow of gas through an orifice. It is as applicableto Venturi or Pitot tubes if the proper value for c is substituted. Q = CAV2gHwhere Q = flow of gas, in cubic feet per second;C = coefficient of flow; A = area of orifice, Ventu
. Transactions. of greatest contraction xd, produces a static pres- G2G MEASUREMENT OF BLAST-FURNACE GAS sure Pi lower than p. In other words, a certain proportion of the initialpressure p is converted into velocity pressure due to the constrictionintroduced in the gas main. The formula that has been developed is as simple and reliable as neces-sary for determining the flow of gas through an orifice. It is as applicableto Venturi or Pitot tubes if the proper value for c is substituted. Q = CAV2gHwhere Q = flow of gas, in cubic feet per second;C = coefficient of flow; A = area of orifice, Venturi throat (or pipe section if Pitottube), in square feet; T X^225 XhP X Dwhere T = absolute temperature of gas, in degrees C;h = difierential pressure, in inches of water;P = absolute pressure of gas, in millimeters of mercury;D = specific gravity of gas referred to air. For Venturi tubes C, the most important and variable value, has beengenerally accepted as to ; it usually varies directly as the ratio. v///y/////////////////77////////\////////////////////////777:^^ Fig. 2.—Characteristics op gas flow through orifice plate and locationof pressure connections for recorder. of the throat diameter to the upstream pipe diameter. For Pitot tubes,the value C varies anywhere from to unity, due to the many differenttypes of Pitot tubes used and their relative location in the gas some cases traverses of the gas main are made in order to obtain anaverage velocity reading; in others, the tube is permanently located ina certain position and the value of C adjusted accordingly. For an orifice-plate installation, the curves developed by J. M. Spitz-glass for determining the value of C, shown in Fig. 3, were used. Aninspection of these curves will show that as the diameter of the orificeapproaches the diameter of the pipe in which it is installed, the value ofC approaches unity. Nearly all authorities agree that it is best to keep D. L. WARD AND R. S. REED 627 the rati
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
