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CHAPTER 46 .
:1948 Guide -
- Table -1. Rates of Flow Through Branch Pipes of Woodworking Machines-
Pipe Diameter, In.
3 4 5
Air Volume, Cfm .
200 . 350
550
Pipe Diameter, In.
6 ... -7. 8
Am Volume, Cfm
800 1100 1400
Table 2. Branch Pipe Size for Woodworking Machine Hoods
Type of Machine
`. Size, In.
. Min.
Max.
No. OF
Branches
Minimum Diameter, In.
Bottom Branch
Top Branch
Others
Self feed table saw
254
Other single, saws
18 '
1
18 : 1
4' 5 '
Saws with Dado Head.
15
Band saws
--
'2 2. 3 36
2 2 2
4 4 5 4 5 .5
Disc Sanders
. 18 . 26 32 '
38
1-18 28 32
38 48
14
1- ' - 5 . .
2
:4
.4
254
3 5 4 . -. .4
Triple drum'sanders
3030 . 36 36 42 . . 42 48
1 1 1 1
78 9 10
Single drum sanders: (area in sq-ita.) '
350 700 '1400
350
. 700 1400 ' 2800
.j
4a
5 6 7
Horizontal belt sanders Vertical belt sanders' ' ' Jointers Single planers' '
i , 9
9
2- - . 5 . - 4
2- .
6.
4
6 -' .9
:6
9' 14 .
.1'"
4:
1 1 " 5-`
1 - : ; 6
1
`8 > j
8 ; 20
` 1'
j: 1 4 ; ' 5
' ' 20 : ., - r- :
5 "-
20
26 : 1
6 .
26' 36 1 -'7 - '
j . .
> 1,,
Tenoner ` ;
,
'2
:5
5
.. aNot over 10 in., diameter.. Table:3. Rates of-Flow Through Branch Pipes, Grinding and Buffing Wheels
. Pipe Diameter, In..
Am Volume, Cfm
3 G. : 4 ... - ... ; 5'
- 225 -,.400 .600
.
. Pipe Diameter, In.
6 -7-
Air. Volume, Cfm
900 ,1200
Exhausting and Conveying Systems', ",
831
Table 4.- Branch Pipe Sizes for Grinding and Buffing Hoods\ ,>
; .'> , V
Type of. Wheel*
: i `.
* j ' -
Grinding
Disc Grinding'
Buffing, Polishing and Scratch Brushing
Wheel Size Diameter, In.
Min.
Max. '
9
9 18 18 24. 24 30
30 36
=;' Maximum
* Width. `Area '*
... la.
. Sq.ln.
Branch Pipe . Minimum Diameter.
i 30' . 3
3 - .175 . 4
.-4 . ,300
.5
5 500
6
6
.7f.
... . 7.
''
20 ;300 20 30 __
8 8 16 16 24 24 , 30 ;
2.
50
3 150
4 300
6. 600
3^ 4
5 6
enclosure of an operation. This procedure is strongly urged where dusts are directed beyond the zone of influence of the hood.
Axial Velocity Formula for Hoods
When the normal- flow of air, into a hood is unobstructed, Equation 3 may be used to determine the air velocity at any point along the axis6:
y - 01 Q
* + 0.1 A
where
V =. velocity at point, feet per.minute. . Q volume of air handled; cubic feet per minute. * = distance along axis, feet. A = area of opening, square feet.
,'
(3)
Velocity Contours
It is possible by use of a-spedally constructed Pitot tube7 to map contours of equal velocity in any. axial plane located in the field of in fluence. It has-been found that the positions of these contours for any hood can be expressed as percentages of the velocity at the hood opening and are purely functions of the shape of the hood8.
Table 5. Recommended Air Velocities-Through ^Openings -in-Hoods-'Enclosing Operations or Located Over Zones or'Generation of Dusts, Fumes, Vapors and Gases Released in Certain Manufacturing Processes
. Condition op Gknkration of Contaminant ' 1
Minimum Air Velocity, FPM
Released without noticeable movement. Releasedwith low velocity
Active generation---------,----Released With great force....
50-100 100-200 i ;
200-500 506-2000 '
Evaporation of, vapors,, exhaust from
' pickling, washing,-'degreasing',' 'plating!
- w'eldirig; etc.' ' :
Paint:sprayirig-in'booth;inspection,sort-
ing, weighing, packaging, low speed
conveyor transfer points,,rotating.rnixr
tures, barrel filling.
Foundry-shakeout,, high speed conveyor
transfer; points, .crushers,. screens,. .
Grinding, tumbling' mills; abrasive clean-
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