PROPORTIONING THE SIZE OF MAINS

For any size system of steam or water heating the following rule will be found entirely satisfactory for mains 100 feet long; for each 100 feet additional use a size larger ratio.

Rule.—

r = (3.1416/d)R = a/r × 100.

r represents ratio of main in inches for each 100 feet of surface; d, diameter of pipe; R, quantity of radiation carried by size of pipe; a, area of pipe in inches.

From this the following table has been constructed:

Diameter of pipe	Area of pipe	Ratio to each 100 feet of surface	Quantity of radiation, steam or water, on a given size pipe
1½	1.767	2.10	84
2	3.141	1.57	200
2½	4.908	1.25	400
3	7.069	1.04	700
3½	9.621	0.90	1,062
4	12.566	0.78	1,590
4½	15.904	0.70	2,272
5	19.625	0.63	3,120
6	28.274	0.52	5,440
7	38.484	0.45	8,550
8	50.265	0.40	12,556
9	63.617	0.35	18,100
10	78.540	0.30	25,300