Modern Gasworks Practice

494 MODERN GASWORKS PRACTICE Horse-power requibed to Pass Gas agatnst Various Pressures. (Friction of Exhauster neglected.) Capa city per Hour. Cubic feet. Total Pressure of Gas in Inches of Water. 6 9 12 15 18 20 24 30 36 40 50 5,000 0-08 0-12 016 0-19 0-24 0-26 0-31 0-39 0-47 0-53 0-66 10,000 0-16 0-24 0-31 0-39 047 0-53 0-63 0-79 0-95 1-05 1-31 15,000 0-24 0-36 0-47 0-58 0-71 0-79 0-94 1-18 142 1-58 1-97 20,000 0-31 047 0-63 0-79 0-95 105 1-26 1-58 1-90 2-10 2-63 25,000 0-39 0-59 0-79 0-98 1-18 1-31 1-58 1-97 2-37 2-63 3-29 30,000 0-48 0-71 0-94 1-18 1-42 1-57 1-89 2-36 2-83 315 3-94 40,000 0-62 0-94 1-26 1-58 1-90 2-10 2-52 3-15 3-78 4-21 5-26 50,000 0-79 1-18 1-58 1-97 2-36 2-63 3-15 3-94 4-73 5-25 6-57 60,000 0-94 1-41 1-89 2-36 2-84 315 3-79 4-73 5-67 6-30 7-80 80,000 1-24 1-84 2-52 3-16 3-80 4-20 5-04 6-30 7-56 8-42 10-5 100,000 1-58 2-37 3-16 3-94 4-73 5-26 6-31 7-89 9-47 10-5 13-15 150,000 2-37 3-54 4-72 5-90 7-09 7-87 9-46 11-8 14-2 15-8 19-7 200,000 3-16 4-74 6-32 7-88 9-46 10-5 12-6 15-8 18-9 21 -0 26-3 250,000 3-95 5-92 7-90 9-85 11-8 13-1 15-7 19-7 23-6 26-2 32-9 300,000 4-74 7-11 9-48 11-8 14-1 1.5-7 18-9 23-6 28-4 31-5 39-4 The additional allowanöe for friction will vary from 40 to 100 per cent, of the figures given by the above table. As an illustration of this item, the following examples are given :— Bergest,\GE to Add to Powers given in above Table in order to tind Hobse-poweb to Drive Exhauster Capacity per Höur. Back-pressure. Add to previous Power. 10,000 cubic feet 12 inches 100 per cent. 20,000 „ „ . ... . 18 90 50,000 „ „ ... . 24 „ 70 100,000 „ „ . . . . 30 „ 50 200,000 „ „ ... . 36 „ 45 300,000 „ „ 50 „ 40 Thus for an exhauster passing 100,000 cubic feet against 30 inches back-pressure an engine of about 12 b.h.p. would suffice, although it is always as well to allow an additional margin of 25 per cent., bringing the total brake horse-power up to 15. Steam-Jet Exhausters Steam-jet exhausters working on. the injector principle are comparatively rare features of the modern gasworks in this country, although they continue to find