The best Velocity of Circumference for different Densities.

 Velocity of Circumference. Feet per Second. Density of Blast. Oz. per inch. 170 3 180 4 195 5 205 6 215 7

A speed of 180 to 200 feet per second, giving a density of 4 or 5 oz., is very suitable for smithy fires.

250 to 300 feet per second is a proper speed for cupolas.

A fan 4 feet 0 inch diameter, blade 1 foot 0 inch square, will supply 40 fires with 1 5/8 tuyeres at a density of 4 oz.

To find the Horse Power required for any fan,

Let D = density of blast in oz. per inch.

A = area of discharge at tuyeres in square inches. V = velocity of circumference in feet per second.

Then V2 / 1000 X D X A / 963 = Effective Horse Power required.

To find the density to be attained with any given fan. Let D = diameter of fan in feet.

Then (V/4)2 / 120 X d. = Density of blast in oz. per inch. Or the density may be found by comparison with the following table: -

 Velocity of Circumference. Feet per Second. Area of Nozzles. Density of Blast. Oz. per inch. 150 Twice area of blades 1 150 Equal ditto 2 150 1-2 ditto 3 170 1-4 ditto 4 200 1-2 ditto 4 200 1-6 ditto 6 220 1-3 ditto 6

To find the quantity of air that will be delivered by any Fan, the density being known.

Total area nozzles, sq. ft. X velocity, ft. per minute corresponding to density (as per table) = Air delivered, cubic ft. per minute.

 Density. Oz. per Sq. Inch. Velocity. Feet per Minute. 1 5,000 2 7,000 3 8,600 4 10,000 5 11,000 6 12,250 7 13,200 8 14,150 9 15,000 10 15 800 11 16,500 12 17,300
 Density. Lbs. per Sq. Inch Velocity. Feet per Minute. 1 20,000 1½ 24,500 2 28,300 2½ 31,600 3 44,640 4 40,000 6 49,000 8 56.600 10 63,200 12 69,280 15 78,000 20 89,400