42 
BULLETIN 1373, U. S. DEPARTMENT OF AGRICULTURE 
in the first column in the table. Reading across, the height of the 
hood (H) is 3 7 j/2 inches to the apex of the cone, and the width ( W) 
is 11 3^ 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. — Dimensioiis 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 ' 8-inch 
pipe j pipe 
9-inch 
pipe 
10-inch 
pipe 
Inches 
12% 
im 
15 
mi 
17% 
mi 
20 
Inches 
8% 
7% 
7% 
6% 
6% 
5% 
5% 
5 
4% 
4% 
Inches 
Inches 
Inches 
Inches 
Inches 
Inches 
Inches 
11 inches _ 
12inches..- 
13 inches. ... .. 
11% 
11 
10% 
9% 
9 
s% 
8 
7% 
7% 
7 
6% 
6% 
6% 
15 inches. 
15 
14 
13% 
12% 
12 
11% 
11 
10% 
10 
9% 
9% 
9 
8% 
8% 
8 
7% 
17 inches . .. ... . 
21% 
22% 
23% 
25 
26% 
27% 
28% 
30 
31% 
32% 
33% 
35 " 
36% 
371-3 
38% 
40 
41% 
42% 
43% 
45 
46% 
47% 
48% 
50 
51% 
52% 
53% 
55 
56% 
57H 
58% 
60 
61% 
62% 
63% 
65 
66% 
67% 
68% 
70 
71% 
72% 
73% 
75 
18 inches . ... .. 
19 inches . 
18 
17% 
16% 
15% 
15 
14% 
13% 
13% 
12% 
12% 
12 
11% 
11 
10% 
10% 
10% 
9% 
9% 
9% 
20 inches . . 
21 inches 
22 inches ... 
21% 
20% 
19% 
18% 
18 
17% 
16% 
16 
15% 
15 
14% 
14% 
13% 
13% 
13 
12% 
12% 
12 
11% 
11% 
11% 
11 
10% 
23 inches 
25 inches.. . 
24% 
23% 
22% 
21% 
21 
20% 
19% 
19 
18% 
18 
17% 
17 
16% 
16 
153* 
15% 
15 
14% 
14% 
14 
13% 
13% 
13 
12% 
12% 
12% 
26 inches.. .. 
28 inches . 
27% 
26% 
25% 
25 
24% 
23% 
22% 
22 
21% 
21 
20% 
19% 
19% 
19 
18% 
18 
17% 
17% 
16% 
16% 
16 
15% 
15% 
15% 
15 
14% 
14% 
14 
13% 
29 inches 
30 inches 
303% 
29% 
32 inches 
33 inches ... . 
28% 
28 
27% 
26% 
25% 
25 
38 inches . 
39 inches ... .. - 
24% 
40 inches.. .. 
23% 
41 inches 
23% 
22% 
22% 
21% 
21% 
45 inches 
46 inches. ._. .. ... 
20% 
20% 
48 inches 
20 
19% 
19 
18% 
52 inches . ... 
18% 
53 inches 
18 
54 inches 
17% 
17% 
17 
16% 
16% 
59inches ._ 
16% 
60 inches 
16 
1 
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 \]/ 2 inches from the face of 
