163

C.-3

Table No. 2. — Divisions of Hydraulic Head for ascertaining Effective Horse-power per Sluice-head of Water.

Examples. 1. What actual horse-power will be realised by a Pelton wheel having an efficiency of 90 per cent., with one sluice-head of water and 400 ft. total head, less 20 ft. loss of head from friction &c. in pipes conveying the water to wheel ? 400 - 20 = 380 ft. hydraulic head, and this, divided by the number opposite 90 per cent, in Table 2 (9777) equals the horse-power =;=== = 38-86-horse power. 2. What actual horse-power will be realised by an undershot wheel having an efficiency of 35 per cent, in the forty sluice-heads of water and 3 ft. hydraulic head ? 40 x 3 . „„ , WsM = 4'77-horse power. 3. What actual horse-power will be realised by a low-breast wheel having an efficiency of 55 per cent., with 33-J- sluice-heads of water and 10 ft. hydraulic head? — = 20-8-horse power. 4. What actual horse-power will be realised by a high-breast wheel having an efficiency of 60 per cent., with 33J sluice-heads of water and 15 ft. hydraulic head? ■w.'aAft = 34-09-horse power. 5. What actual horse-power will be realised by an overshot wheel having an efficiency of 65 per cent., with sluice-heads of water and 20 ft. hydraulic head ? = 49-24-horse power. 6. What actual horse-power will be realised by a turbine wheel having an efficiency of 70 per cent., with one sluice-head of water and 300 ft. total head, when the loss by friction, &c, in the pipes conveying the water to the wheel is 15 ft. of head ? 300 - 15 = 285 ft. hydraulic head. 12-571 = 22-67-horse power. 7. What actual horse-power will be realised by a Pelton wheel having an efficiency of 85 per cent., with one sluice-head of water and 400 ft. total head, the loss by friction, &c, being 20 ft. of head? 400 - 20 = 380 ft. hydraulic head. 10 , 352 = 36-7-horse power. 22—0. 3.

(Calculated fj :om percentage = head re 1 uirei per horse-powe ••) Efficiency of Motor. Division. II Efficiency of Motor. Division. Efficiency of Motor. Division. 100 per cent. 99 98 97 „ 96 „ 95 94 „ 93 92 „ 91 „ 90 89 88 87 „ 86 „ 85 84 83 „ 82 „ 81 80 79 „ 78 „ 77 „ 8-800 8-888 8-979 8-072 9-166 9-263 9-361 9-462 9-565 9-670 9-777 9-887 10-000 10-115 10-232' 10-352 10-476 10-602 10-731 10-864 11-000 11-139 11-282 11-482 I 76 per cent. 75 74 „ 73 „ 72 71 70 „ 69 68 67 66 65 64 „ 63 62 „ 61 60 59 58 57 56 55 „ 54 , 53 . „ 11-578 11-733 11-891 12-054 12-222 12-394 12-571 12-753 12-941 13134 13-333 13-538 13-750 13-968 14-193 14-426 14-666 15-915 15-172 15-438 15-714 16-000 16-296 16-603 52 per cent. 51 « 50 49 48 47 46 „ 45 „ 44 43 42 „ 41 „ 40 39 38 „ 37 „ 36 „ 35 „ 34 „ 33 „ 32 „ 31 „ 30 „ 16-923 17-254 17-600 17-959 18-333 18-723 19130 19-555 20000 20-465 20-952 21-463 22-000 22-564 23-157 23-783 24-444 25-142 25-882 26-666 27-500 28-387 29-333