42 
BULLETIN 1373, IT. S. DEPARTMENT OF AGRICULTURE 
in the first column in the table. Reading across, the height of the 
hood (H) is 373^ inches to the apex of the cone, and the width ( W) 
is 11^2 inches for a 6-inch pipe connection. If a larger pipe connec- 
tion is desired, the width of the hood only need be changed to care 
for the extra volume of air at a permissible velocity. 
Table 6. — Dimensions of United States Department of Agriculture hood (fig. 32) 
Height 
(H) 
Width (W) 
Length of opening (L) 
Diameter of pipe connection (D) 
3-inch 
pipe 
4-inch 
pipe 
5-inch 
pipe 
6-inch 
pipe 
7-inch 
pipe 
8-inch 
pipe 
9-inch 
pipe 
10-inch 
pipe 
10 inches 
Inches 
15 
1634 
17J4 
mi 
20 
Inches 
m. 
7M 
734 
6M 
634 
5M 
&A 
5 
4M 
43-2 
Inches 
Inches 
Inches 
Inches 
Inches 
Inches 
Inches 
12 inches 
13 inches __ 
11 
10M 
93^ 
9 
8 
7H 
734 
7 
6M 
6H 
634 
14 inches 
16 inches. . 
15 
14 
1334 
12 
nn 
11 
1034 
10 
9M 
934 
9 
83^ 
834 
8 . 
7H 
17 inches ... 
2134 
223^ 
23M 
25 
2634 
27J/2 
28^ 
30 
3134 
3234 
3334 
35 
3634 
3734 
38M 
40 
4134 
42^ 
43^ 
45 
4634 
4731 
48^ 
50 
5134 
521/3 
53M 
55 
5634 
5734 
58M 
60 
6i?4 
6234 
63^ 
65 
6634 
673^ 
68^ 
70 
7134 
72^ 
73M 
75 
18 inches . _ . . 
19 inches. _. 
18 
1734 
163^ 
15M 
15 
1434 
13M 
1334 
12M 
1234 
12 
11 
10M 
ioy 2 
1034 
WA 
vy 2 
934 
20 inches. _ _ 
21 inches, ... . . . . 
22 inches . _ -...._ 
2134 
2034 
im 
18M 
18 
1734 
1634 
16 
153^ 
15 
14H 
1434 
13M 
133-3 
13 
12% 
1234 
12 
1124 
11H 
HM 
11 
10M 
23 inches _ 
24 inches . . 
25 inches... . . ... 
243^ 
233^ 
22H 
21M 
21 
203^ 
1934 
19 
183^ 
18 
173^ 
17 
163^ 
16 
153,4 
1534 
15 
143^ 
1434 
14 
13H 
1334 
13 
12M 
12^ 
1234 
26 inches . 
27 inches . 
28 inches. . . . . 
27V 2 
26H 
25M 
25 
2434 
233^ 
22M 
22 
2iy 2 
21 
2034 
1934 
1934 
19 
183^ 
18 
173^ 
1734 
16^4 
16H 
16 
15^4 
15H 
1534 
15 
143^ 
1434 
14 
13*4 
31 inches. ... 
30M 
29^ 
28 
34 inches . 
35 inches ... 
27J4 
263^ 
25^4 
25 
38 inches. -. . 
39 inches . . 
24H 
2334 
2334 
42 inches 
22^ 
43 inches . . . _._.... 
2234 
21^4 
45 inches ... 
2134 
46 inches . . 
20?4 
20 
49 inches. . 
IW2 
19 
18% 
1834 
18 
17^4 
1734 
17 
16 3 /£ 
163^ 
1634 
16 
At a velocity of 7,275 feet per minute, the maximum which could 
be obtained with the United States Department of Agriculture hood 
in a 7-inch pipe, with the fan equipment shown in Figure 30, fine 
wheat scourings on a tray were just moved by small eddies when the 
tray was 12 inches from the face of the hood, and wheat and oat 
chaff were just picked up from a screen 4J^ inches from the face of 
