Values of coefficient of entry Ce
Typical values of Ce are shown in Figures 3.46 to 3.52.
О
|
Diametir mm |
C. |
|
100 |
765 |
|
150 |
-745 |
|
200 |
— 735 |
|
250 |
• 725 |
At about 20 m/s in duct. Ca is less at lower velocity Figure 3.46 Ce for plain open ended duct
|
Open |
Flanged |
|||
|
D mm |
Mouth mm |
L mm |
C. |
C. |
|
75 |
75*225 |
150 |
809 |
849 |
|
100 |
100 x 300 |
200 |
854 |
865 |
|
125 |
125 x 375 |
225 |
814 |
844 |
|
200 |
200 x 600 |
300 |
785 |
804 |
|
Figure 3.50 |
Ce for rectangular hoods ratio 1 : 3
|
Diameter mm |
C. |
|
100 |
86 |
|
150 |
• 855 |
|
200 |
•835 |
|
250 |
•81 |
At about 20 m/s in duct. Ce is less at lower velocity Figure 3.47 Ce for flanged open ended duct
|
Open |
Flanged |
|||
|
0 mm |
Mouth mm |
L mm |
— |
C. |
|
100 |
100×125 |
125 |
.849 |
89 |
|
150 |
190 x 250 |
175 |
• 838 |
865 |
|
Ј |
|
Angle 0 |
|
Figure 3.51 Ce for rectangular hoods ratio 3 : 4 |
|
Round |
Square |
|||
|
Included angle 6 |
Pipe 200 mm dta |
Pipe less than |
Pipe 200 mm |
Pipe less than |
|
Or largtr |
200 mm dia |
Square or larger |
200 mm square |
|
|
20- |
.96 |
■91 |
• 94 |
89 |
|
40* |
• 99 |
• 93 |
• 95 |
90 |
|
60′ |
•98 |
• 92 |
• 94 |
88 |
|
75* |
• 96 |
• 91 |
• 93 |
• 87 I |
|
90* |
• 95 |
• 90 |
•91 |
85 |
|
120* |
• 91 |
• 86 |
• 87 |
• 82 |
|
1 150* |
86 |
• 82 |
• 83 |
• 79 ‘ |
Figure 3.48 Ce for tapered hoods
|
|
|
0 mm |
Hood mm |
C. |
|
150 |
Plain with 165 x 50 wheel |
• 80 without wheel — 725 with wheel |
|
250 mm—► |
||
For average hoods including the obstruction of grinding or buffing wheel take Ce at • 71
Figure 3.52 Ce for grinding wheel hoods
Posted in Fans Ventilation A Practical Guide