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Steam and Return Line Sizing

 Parker Boiler

All capacites are shown in pounds per hour and are based on steam and condensate flowing in the same direction



Steam Pipe capacity at 15 psi.
Pipe Size,.
(in) 		 Pressure drop p.s.i  per 100 ft. of pipe length
1/8 1/4 1/2 3/4 1 2
1 27 38 53 65 76 110
1 1/4 59 83 120 140 160 230
1 1/2 91 130 180 220 260 360
2 180 260 370 450 520 740
2 1/2 300 430 600 740 860 1,210
3 560 790 1,110 1,360 1,570 2,220
3 1/2 830 1,180 1,660 2,040 2,350 3,320
4 1,180 1,650 2,350 2,880 3,330 4,700
5 2,180 3,080 4,350 5,330 6,160 8,700
6 3,580 5,060 7,150 8,750 10,120 14,290
8 7,450 10,530 14,880 18,220 21,060 29,740
10 13,600 19,220 27,150 33,250 38,430 54,270
12 21,830 30,840 43,570 53,370 61,690 87,100


Steam Pipe capacity at 50 psi.
Pipe Size,.
(in) 		 Pressure drop p.s.i  per 100 ft. of pipe length
1/4 1/2 3/4 1 2 5
3/4 27 38 47 54 76 120
1 54 77 94 110 150 240
1 1/4 120 170 210 240 340 530
1 1/2 180 260 320 370 520 830
2 370 530 650 750 1,060 1,680
2 1/2 620 870 1,070 1,240 1,750 2,760
3 1,130 1,600 1,960 2,270 3,200 5,060
3 1/2 1,690 2,390 2,390 2,390 4,780 7,560
4 2,390 3,380 4,150 4,790 6,760 10,690
5 4,420 6,250 7,670 8,860 12,500 19,780
6 7,260 10,260 12,590 14,540 20,520 32,470
8 15,120 21,360 26,210 30,280 42,720 67,590
10 27,260 10,260 12,590 14,540 20,520 32,470
12 44,270 62,560 76,780 88,680 125,100 197,900


Steam Pipe capacity at 100 psi.
Pipe Size,.
(in) 		 Pressure drop p.s.i  per 100 ft. of pipe length
1/2 3/4 1 2 5
3/4 50 61 70 99 160
1 100 120 140 200 320
1 1/4 220 270 310 440 690
1 1/2 340 420 480 680 1,080
2 690 850 980 1,390 2,190
2 1/2 1,140 1,400 1,620 2,280 3,610
3 2,090 2,560 2,960 4,180 6,610
3 1/2 3,120 3,830 4,420 6,250 9,870
4 4,420 5,420 6,260 8,840 13,280
5 8,170 10,020 11,580 16,350 25.840
6 13,420 16,450 19,020 26,840 42,410
8 27,930 34,250 39,580 55,870 88,280
10 50,970 62,500 72,230 101,900 161,100
12 81,810 100,300 115,900 163,600 258,500


Steam Pipe capacity at 150 psi.
Pipe Size,.
(in) 		 Pressure drop p.s.i  per 100 ft. of pipe length
1/2 3/4 1 2 5
3/4 59 73 84 120 190
1 120 150 170 240 370
1 1/4 260 320 370 520 830
1 1/2 400 500 570 810 1,280
2 820 1,010 1,170 1,650 2,610
2 1/2 1,360 1,660 1,920 2,720 4,300
3 2,480 3,050 3,520 5,090 7,870
3 1/2 3,710 4,550 5,260 7,430 11,760
4 5,250 6,440 7,440 10,510  16,630
5 9,720 11,920 13,770 19,450 30,780
6 15,950 19,560 22,600 31,930 50,520
8 33,210 74,310 85,860 121,300 191,900
10 60,590 74,310 85,860 121,300 191,900
12 97,250 119,260 137,800 194,700 308,000


Equivalent length of pipe to be added for fittings
Size of pipe, in. Length in feet to be added to run
Standard Elbow Side outlet tee Gate valve (*) Globe valve (*) Angle valve (*)
1/2 1.3 3 0.3 14 7
3/4 1.8 4 0.4 18 10
1 2.2 5 0.5 23 12
1 1/4 3.0 6 0.6 29 15
1 1/2 3.5 7 0.8 34 18
2 4.3 8 1.0 46 22
2 1/2 5.0 11 1.1 54 27
3 6.5 13 1.4 66 34
3 1/2 8.0 15 1.6 80 40
4 9.0 18 1.9 92 45
5 11.0 22 2.2 112 56
6 13.0 27 2.8 136 67
8 17.0 35 3.7 180 92
10 21.0 45 4.6 230 112
12 27.0 53 5.5 270 132


Problem: Assume a Unit operate at 100 P.S.I. and requires 10 H.P.; what size steam and return line should be run if it is located 100 ft. from the boiler?

Solution: 1. Determine the Pounds of Steam required.
10 x 34.5 = 345 Pounds of Steam per Hour.
2. Select Steam Line Size from 100 P.S.I. Table 5
Note: For High Pressure Piping, use 2 P.S.I. Drop/100 Ft. Read 440 Pounds from Table, therefore 1-1/4" Line required.
3. Select Return LIne Size
Read 419 Pounds from Table; under 100 PSI High Pressure Return Column. Therefore, 3/4" Line required.


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   Steam Return Line Sizes

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