BOILER TUBES.
Reading edition
The following table gives the draught area and heating surface of the various sized boiler tubes and flues:
External Diameter. Draught area in sq. inches. Draught Area in sq. feet. Heating surface in feet per ft. of tube in length. No. of tubes in 1 sq. foot of draught area.
5/8 ...... ...... .1636 .....
¾ ...... ...... .1963 .....
1 .575 .0040 .2618 250.0
1¼ .968 .0067 .3272 149.3
1½ 1.389 .00964 .3927 103.7
1¾ 1.911 .0133 .4581 75.2
2 2.573 .0179 .5236 55.9
2¼ 3.333 .0231 .5891 43.3
2½ 4.083 .0284 .6545 35.2
2¾ 5.027 .0349 .7200 28.7
3 6.070 .0422 .7854 23.7
3¼ 7.116 .0494 .8508 20.2
3½ 8.347 .0580 .9163 17.2
3¾ 9.676 .0672 .9818 14.9
4 10.93 .0759 1.0472 13.2
4½ 14.05 .0996 1.1781 10.2
5 17.35 .1205 1.3090 8.3
6 25.25 .1753 1.5708 5.7
7 34.94 .2426 1.8326 4.1
8 46.20 .3208 2.0944 3.1
9 58.63 .4072 2.3562 2.5
10 72.23 .5016 2.6180 2.0