548
Molesworth’s pocket-book
Power required for Fans.
p = Pressure of blast in lbs. per square inch.
A = Area of the sum of the tuyeres in square
inches.
V = Velocity of tips of fan in feet per second.
HP — Indicated horse-power required.
HP = -000016 V2 A p.
Proportions of Fans.
Length of vanes = ? Width of vanes = 5 .
4 4
Diameter of inlet — -. Eccentricity of fan = ~
Length of spindle journal = 4 diameters of
Spindle. Diameter of smith’s forge nozzle, 11.
Smithy blast from 0’25 to 0’3 lb. per square
inch. Cupola blast about 0'8 lb. per square inch.
Blowing Engines.
Capacity of air-vessel = 20 times the capacity of
the blowing cylinder if the cylinder is single-
acting, or 10 times if double-acting.
Velocity of air in the passages should not exceed
35 feet per second. Density of blast for iron
furnaces from 21 to 3 lbs. per square iuclu
Each smith’s forge requires 150 cube feet of air
per minute. Density of smith’s forge blast i lb.
per square inch. Each ton per hour melted in
cupola requires 3500 cube feet per minute. Each
finery forge requires 100,000 cube feet air for each
ton refined. Each blast furnace 20 cube feet per
minute for each cube yard capacity of furnace.