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