Page:Steam heating and ventilation (IA steamheatingvent00monrrich).pdf/79

 steam heating, gave a rule for proportioning steam pipes which is very convenient and has been very widely used. This rule states that in the sectional area of the pipe there should be allowed the area of a 1-inch pipe for every 100 square feet of radiator surface. Inasmuch as the areas of circles are proportional to the square of their diameters, this means a 1-inch pipe for 100 square feet, 2-inch pipe for 400 square feet, 3-inch pipe for 900 square feet, 8-inch pipe for 6,400 square feet, etc. These sizes are none too large for many cases, although in plants with the system carefully arranged so that the circulation is all in one direction and the water of condensation does not have to flow back against the current of steam, pipes can be very considerably decreased below the sizes given by this rule. Mr. Baldwin also gives a diagram of minimum sizes for short horizontal supply mains from which few branches are taken, which give sizes very much smaller than the rule above quoted. [ See Table I. ]

Mills' rule for pipe sizes.—Mr. J. H. Mills gives a diagram for the sizes of mains for one-pipe overhead systems of which he is the originator. This diagram gives sizes somewhat smaller than those obtained by Mr. Baldwin's rule. In the accompanying table are given the maximum square feet of radiation on pipes of each size according to the rules of Baldwin and Mills, as well as Mr. Baldwin's sizes for return pipes. In regard to his figures for minimum sizes for mains, Mr. Baldwin states that they represent minimum conditions for lengths of 50 feet or thereabout, but that for large buildings one size larger should be used.

Monroe's rule for pipe sizes.—In his own practice the author has divided mains and risers of steam-heating systems into the following classifications:

(a) Supply mains for one-pipe systems, which carry all water of condensation, but in the direction that the steam flows.

(b) Mains for two-pipe or one-pipe overhead systems, into which there is no water of condensation from the radiators.