Document zoa2O2JVq9x1y8872dDLRkJz

American Society of Heating and Ventilating Engineers Guide, 1926-27 to be handled from direct radiation, direct-indirect radiation and indirect or fan blast radiation may be estimated as follows: where For direct radiatiqn W = 0.3 R For direct-indirect radiation W = 0.6 R -ror .ind,.irec,t rad,.iati.on .W.. = Q,X, 60w X..--T 55.6 X H . W = lbs. of condensate per hour, R = sq. ft. of radiation, Q = cu. ft. of air per min., T = temperature rise of air in deg. fahr. and H = the latent heat of steam in the system in B.t.u. per pound. The normal capacity of pumps to be based on condensate at a tempera ture of not over 180 deg. fahr. For temperature of condensate above 180 deg. fahr. capacity should be increased above that estimated for 180 deg. fahr. condensate as per the following Table 63. Table 63. Temperature of Condensate at Pump Suction Deg. fahr. 190 200 204 Factor 1.15 1.56 2.00 To use Table 63, multiply the quantity of condensate to be handled by the factor corresponding to the temperature of the condensate at the pump suction and select a pump suitable for the quantity thus found. The above increase in pump capacity may be reduced by providing a static head above the pump suction and when this static head is made equivalent to 15 ft. minus the absolute boiling pressure of the condensate (measured in feet of water) no increase is necessary. Allow sufficient head in addition to the total head necessary to over come static head, velocity head, pipe friction and boiler pressure, wherever condensate is to be returned direct to a boiler from the pump. BOILER FEED PUMPS Types.--Boiler Feed Pumps may be of the following types: 1. Direct acting steam driven reciprocating pumps. 2. Power driven reciprocating pumps. 3. Centrifugal pumps. 4. Screw pumps. Capacities.--The capacity of a boiler feed pump should be based on 34.5 lb. of water per hour per maximum boiler horsepower served, with a slippage allowance of 10 per cent in the water cylinders and a factor of safety allowance of 2 for intermittently operating pumps and a factor of safety allowance of 1)4 for continuous operating pumps, to provide for unusual demands when the water in boilers becomes low or excessive loads are carried. 0 Piston Speeds in Feet per Minute.--For reciprocating boiler feed pump 126 American Society of Heating and Ventilating Engineers Guide, 1926-27 not to exceed 10 times the square root of the number of inches in the length of stroke of the water pistons. Direct acting reciprocating steam driven or power driven boiler feed pumps are generally found to be more efficient for smaller installations especially with widely fluctuating loads as the efficiencies of centrifugal Table 64. Direct Acting Steam Driven Duplex Reciprocating Boiler Feed Pumps Dia. OF Dia. OF Steam Water Cyl. Cyl. IN . in Inches Inches Length of Stroke in Inches No. of Strokes per Min. Discharge in Gallons Per Per Stroke Min. Equiva lent Dla. of StNGLE Cyl. Pump Boiler H. P. Served Without Factor of Safety S izb Pipe, INCHE s Steam Ex haust Suc Dis tion charge 32 4A 2% 3A 6' * 4 FA 4A iy2 5 10 6 12 7 3 70 4 60 5 50 6 50 6 so 10 40 10 40 12 . 35 0.04 5.6 2Vs . 80 A IA i 0.10 12.0 4 180 A A i A iA 0.20 20.0 5 300 A m 2 iA 0.33 33.0 5A 480 l 1A 2A 2 0.42 42.0 6Vs 600 1A 2 3 iA 0.85 68.0 7 1000 lA 2 3 2A 1.22 97.6 8A 1400 2 2A 4 3 2.00 140.0 9A 2000 2A 3 5 4 Table 65. Horizontal Duplex Piston Packed Power Driven Boiler Feed Pumps for 100 Lb. Working Pressure Size of Pump Cylinders in Inches Dia. Stroke No. of Revolu tions per Min. Displacement Gallons Per Rev. Per Min. 2A 4 34 3A 5 46 8 10 30 0.34 10.2 30 0.49 14.7 30 0.83 24.9 25 1.30 32.5 20 8.69 173.8 Boiler H. P. Served Without Factor of Safety 148 213 361 471 2520 H. P. Required to Drive Pump 1.5 4.0 3.5 4.0 18.0 Pipe Sizes Inches Suction iA 2 2A 3 5 Discharge m 1A 2 iA 4 Table 66. Reciprocating Single Acting Power Driven Triplex Boiler Feed Pumps for 150 Lb. Working Pressure Size of Pump Cylinders in Inches Dia. Stroke No. of Revolu tions per Min. Displacement Gallons Per. Rev. Per Min. iA 2 iA 2A 23 2A 4 34 44 46 58 68 8 10 50 0.045 50 0.078 40 0.122 30 0.255 30 0.367 30 0.652 25 0.978 20 2.041 20"-- 2.938 20 6.520 2.25 3.90 4.88 7.65 11.01 19.56 24.45 40.82 58.76 130.40 Boiler H. P. Served Without Factor of Safety 33 57 70 110 160 280 355 . 592 852 1891 H. P. Required to Drive Pump 0.40 0.65 0.80 1.15 1.40 4.60 3.10 5.00 6.00 14.00 Pipe Sizes Inches Suction A l iA iA iA 2 2A 3 3A 4 Discharge .i i ,MA iA iA 2 2A 3 3 127