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Subchapter 7. General Industry Safety Orders
Group 16. Control of Hazardous Substances
Article 107. Dusts, Fumes, Mists, Vapors and Gases

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§5152. Ventilation and Personal Protective Equipment Requirements for Grinding, Polishing, and Buffing Operations.


(a) General. Every establishment performing dry grinding, dry polishing, or buffing shall provide suitable hoods or enclosures that are connected to exhaust systems which are run continuously during operations.

Exception: When the concentration at the operator's breathing zone of any airborne contaminant generated by such an operation is below the applicable limit prescribed in Section 5155 or any other section of Title 8.

(b) Hood and Branch Duct Performance Requirements.

 (1) Hoods connected to exhaust systems shall be used, and such hoods shall be designed, located, and placed so that the dust or dirt particles shall fall or be projected into the hoods in the direction of the air flow. No wheels, discs, straps, or belts shall be operated in such manner and in such direction as to cause the dust and dirt particles to be thrown into the operator's breathing zone. 


 (2) Wheels and belts shall have not less than the minimum exhaust volumes shown in the following tables: 


TABLE V-1.

GRINDING AND ABRASIVE CUTTING-OFF WHEELS.

 
Wheel Diameter .. Wheel Width .. Minimum Exhaust Volume  
(Inches) ........ (Inches) ..... (Cubic Feet/Min.)       
To 9 ................ 1 1/2 ......................... 220
Over 9 to 16 .......... 2 ........................... 390
Over 16 to 19 ......... 3 ........................... 500
Over 19 to 24 ......... 4 ........................... 610
Over 24 to 30 ......... 5 ........................... 880
Over 30 to 36 ......... 6 .......................... 1200
 
 
 Note: For any wheel wider than that shown, increase the table exhaust volume by the ratio of the actual width to the table width. Example: For wheel width = 4 1/2 inches. Minimum Exhaust Volume = 4.5/4 x 610 = 686 (rounded to 690). 


TABLE V-2

BUFFING, POLISHING, AND SCRATCH-BRUSH WHEELS

 
Wheel Diameter .. Wheel Width .. Minimum Exhaust    
(Inches) ........ (Inches) ..... (Cubic Feet/Min.)  
To 9 .................. 2 ...................... 300
Over 9 to 16 .......... 3 ...................... 500
Over 16 to 19 ......... 4 ...................... 610
Over 19 to 24 ......... 5 ...................... 740
Over 24 to 30 ......... 6 ..................... 1040
Over 30 to 36 ......... 6 ..................... 1200
 
 
TABLE V-3

HORIZONTAL SPINDLE DISC GRINDER

 
Wheel Diameter ........ Minimum Exhaust Volume      
(Inches) ................ (Cubic Feet/Min.)         
                  Single Spindle .. Double Spindle  
Up to 12 .............. 220 .................... 610
Over 12 to 19 ......... 390 .................... 610
Over 19 to 25 ......... 610 .................... 880
Over 25 to 30 ......... 610 ................... 1200
Over 30 to 53 ......... 880 ................... 1770
Over 53 to 72 ......... 880 ................... 6280
 
 
TABLE V-4

VERTICAL SPINDLE DISC GRINDER

 
Disc Diameter ......... One-half or More of Disc Covered .... Disc not Covered 
                    ___________________________________________________________
(Inches) ....................... Exhaust Volume ............. Exhaust Volume   
                    Number                                                     
                      [FN1] .... (Cubic                                        
                                   Feet/Min.) .. Number                        
                                                   [FN1] .... (Cubic Feet/Min.)
Up to 20 ............... 1 .......... 500 ........... 2 ................... 780
Over 20 to 30 .......... 2 .......... 780 ........... 2 .................. 1480
Over 30 to 53 .......... 2 .......... 1770 .......... 4 .................. 3530
Over 53 to 72 .......... 2 .......... 3140 .......... 5 .................. 6010
[FN1] Number of exhaust outlets around periphery of hood, or equal distribution
  provided by other means.                                                     
 
 
TABLE V-5

GRINDING AND POLISHING BELTS

 
Belts Width .... Exhaust Volume     
(Inches) ....... (Cubic Feet/Min.)  
Up to 3 ........................ 220
Over 3 to 5 .................... 300
Over 5 to 7 .................... 390
Over 7 to 9 .................... 500
Over 9 to 11 ................... 610
Over 11 to 13 .................. 740
 
 
 (3) Cradles requiring partial enclosures to house the complete operation shall be ventilated sufficiently such that a minimum air velocity of 150 feet per minute shall be maintained over the entire opening of the enclosure. 


(c) Hood Design.

 (1) Vertical-spindle disc grinders shall be encircled with a hood so constructed that the heavy dust is drawn off a surface of the disc and the lighter dust exhausted through a continuous slot at the top of the hood as shown in Figure V-1. 


 (2) Exhaust hoods for floor stands, pedestals, and bench grinders shall be designed as effective as Figure V-2. The adjustable tongue shown in the Figure shall be kept in working order and shall be adjusted within one-fourth inch of the wheel periphery at all times. 


 (3) Swing-frame grinders shall be exhausted in the same manner as provided for cradles, and shall be provided with exhaust booths as indicated in Figure V-3. 


 (4) Hoods for polishing and buffing and scratch-brush wheels shall be constructed to conform as closely to Figure V-4 as the nature of the work will permit. 


 (5) Cradle grinding and polishing operations shall be performed within a partial enclosure similar to Figure V-5. The operator shall be positioned outside the working face of the opening of the enclosure. Cradle enclosures shall be ventilated sufficiently such that a minimum air velocity of 150 feet per minute shall be maintained over the entire opening of the enclosure. 


 (6) Hoods for horizontal single-spindle disc grinders shall be constructed to conform as closely as possible to the hood shown in Figure V-6. 


 (7) Horizontal double-spindle disc grinders shall have a hood encircling the wheels and grinding chamber similar to that illustrated in Figure V-7. The openings for passing the work into the grinding chamber should be kept as small as possible, but must never be less than twice the area of the branch outlets. 


 (8) Grinding and polishing belt hoods shall be constructed as close to the operation as possible. The hood should extend almost to the belt, and 1-inch wide openings should be provided on either side. Figure V-8 shows a typical hood for a belt operation. 


(d) Portable Operations.

Portable grinding, polishing, and buffing operations, whenever the nature of the work permits, shall be conducted within a partial enclosure over which an average face air velocity of not less than 200 feet per minute shall be maintained, or a low volume, high velocity local exhaust hood attachment shall be used. (Title 24, T8-5152)

FIGURE V-1

VERTICAL SPINDLE DISC GRINDER EXHAUST HOOD AND BRANCH PIPE CONNECTIONS



_____________________________________________________________________
                            |                  |           |
      Dia. D inches (cm)    |   Exhaust E      |  Volume   |
____________________________|__________________| Exhausted | Note
                 |          |       |          | at 4,500  |
       Min.      |   Max.   |  No   |          |  ft/min   |
                 |          | Pipes |   Dia.   | ft(3)/min |
_________________|__________|_______|__________|___________|_________
                 |          |       |          |           |
                 |       20 |     1 |   4 1/2  |       500 | When
                 |          |       |          |           | one-half
                 |          |       |          |           | or more
                 |          |       |          |           | of the
                 |          |       |          |           | disc can
                 |          |       |          |           | be hooded,
                 |          |       |          |           | use
                 |          |       |          |           | exhaust
                 |          |       |          |           | ducts as
                 |          |       |          |           | shown at
                 |          |       |          |           | the left.
Over 20 .........|       30 |     2 |     4    |       780 |
Over 30 .........|       72 |     2 |     6    |     1,770 |
Over 53 .........|       72 |     2 |     8    |     3,140 |
_________________|__________|_______|__________|___________|__________
                 |          |       |          |           |
                 |       20 |     2 |     4    |       780 | When no
                 |          |       |          |           | hood can
                 |          |       |          |           | be used
                 |          |       |          |           | over
                 |          |       |          |           | disc,
                 |          |       |          |           | use
                 |          |       |          |           | exhaust
                 |          |       |          |           | ducts
                 |          |       |          |           | as
                 |          |       |          |           | shown
                 |          |       |          |           | at left.
Over 20 .........|       30 |     2 |   5 1/2  |     1,480 |
Over 30 .........|       53 |     4 |     6    |     3,530 |
Over 53 .........|       72 |     5 |     7    |     6,010 |
_________________|__________|_______|__________|___________|__________

Entry loss = 1.0 slot velocity pressure + 0.5 branch velocity pressure.

Minimum slot velocity = 2,000 ft/mn - 1./2 inch slot width.


FIGURE V-2

STANDARD GRINDER HOOD




  Wheel dimension, inches             |               |
______________________________________|    Exhaust    | Volume
                       |              |    outlet,    | of air
       Diameter        |              |    inches     |   at
_______________________|  Width, Max  |       E       | 4,500
          |            |              |               | ft/min
   Min= d |   Max= D   |              |               |
__________|____________|______________|_______________|________
          |            |              |               |
          |         9  |       1 1/2  |             3 |   220
Over 9 ...|        16  |           2  |             4 |   390
Over 16 ..|        19  |           3  |         4 1/2 |   500
Over 19 ..|        24  |           4  |             5 |   610
Over 24 ..|        30  |           5  |             6 |   880
Over 30 ..|        36  |           6  |             7 | 1,200
__________|____________|______________|_______________|____

FIGURE V-3

A METHOD OF APPLYING AN EXHAUST

ENCLOSURE TO SWING-FRAME GRINDERS

Note: Baffle to reduce front opening as much as possible.




FIGURE V-4

STANDARD BUFFING AND POLISHING HOOD


_____________________________________________________________________
                                             |               |
   Wheel dimension, inches                   |               |
_____________________________________________|    Exhaust    | Volume
                              |              |    outlet,    | of air
            Diameter          |              |    inches     |   at
______________________________|  Width, Max  |       E       | 4,500
                 |            |              |               | ft/min
   Min= d        |   Max= D   |              |               |
_________________|____________|______________|_______________|________
                 |            |              |               |
                 |         9  |           2  |         3 1/2 |   300
Over 9 ..........|        16  |           3  |             4 |   500
Over 16 .........|        19  |           4  |             5 |   610
Over 19 .........|        24  |           5  |         5 1/2 |   740
Over 24 .........|        30  |           6  |         6 1/2 | 1,040
Over 30 .........|        36  |           6  |             7 | 1,200
_________________|____________|______________|_______________|______


FIGURE V-5

CRADLE POLISHING OR GRINDING ENCLOSURE

Entry Loss = 0.45 velocity pressure for tapered takeoff




FIGURE V-6

HORIZONTAL SINGLE-SPINDLE DISC GRINDER

EXHAUST HOOD AND BRANCH PIPE CONNECTIONS



______________________________________________________________
                                     |           |
      Dia D inches                   | Exhaust E |   Volume
_____________________________________|   dia.    | exhausted
                     |               |  inches   |  at 4,500
       Min.          |      Max.     |           |   ft/min
                     |               |           | ft(3)/min
_____________________|_______________|___________|_____________
                     |               |           |
                     |           12  |        3  |    220
Over 12 .............|           19  |        4  |    390
Over 19 .............|           30  |        5  |    610
Over 30 .............|           36  |        6  |    880
_____________________|_______________|___________|_____________

NOTE: If grinding wheels are used for disc grinding purposes, hoods must conform to structural strength and materials as described in 9.1.
Entry Loss =0.45 velocity pressure for tapered takeoff.
Note: If grinding wheels are used for disc grinding purposes, hoods must conform to structural strength and materials as described in 9.1.

Entry Loss = 0.45 velocity pressure for tapered takeoff.


FIGURE V-7

HORIZONTAL DOUBLE-SPINDLE DISC GRINDER

EXHAUST HOOD AND BRANCH PIPE CONNECTIONS



_____________________________________________________________________
                            |                  |           |
       Disc dia.inches      |                  |  Volume   |
                            |   Exhaust E      | exhausted |
____________________________|__________________|    at     |  Note
                 |          |       |          |   4,500   |
       Min.      |   Max.   |  No   |          |  ft/min.  |
                 |          | Pipes |   Dia.   | ft(3)/min |
_________________|__________|_______|__________|___________|_________
                 |          |       |          |           |
                 |      19  |     1 |        5 |      610  |
Over 19 .........|      25  |     1 |        6 |      880  | When
                 |          |       |          |           | width "W"
                 |          |       |          |           | permits,
                 |          |       |          |           | exhaust
                 |          |       |          |           | ducts
                 |          |       |          |           | should
                 |          |       |          |           | be as
                 |          |       |          |           | near
                 |          |       |          |           | heaviest
                 |          |       |          |           | grinding
                 |          |       |          |           | as
                 |          |       |          |           | possible.
Over 25 .........|      30  |     1 |        7 |    1,200  |
Over 30 .........|      53  |     2 |        6 |    1,770  |
Over 53 .........|      72  |     4 |        8 |    6,280  |
_________________|__________|_______|__________|__________
Entry Loss = 0.45 velocity pressure for tapered takeoff.

FIGURE V-8

A TYPICAL HOOD FOR A BELT OPERATION



 
____________________________________________________
Belt Width W, inches .. Exhaust Volume, ft3/min.  
____________________________________________________
up to 3 ............... 220                         
3 to 5 ................ 300                         
5 to 7 ................ 390                         
7 to 9 ................ 500                         
9 to 11 ............... 610                         
11 to 13 .............. 740                         
____________________________________________________
 
 
Minimum duct velocity = 4,500 ft/min branch, 3,500 ft/min main.

 
Entry loss = .. 0.45 velocity pressure for tapered takeoff.   
                0.65 velocity pressure for straight takeoff.  
 
 

    Note: Authority and reference cited: Section 142.3, Labor Code.  


 HISTORY 
   
1. New section filed 7-18-75; effective thirtieth day thereafter (Register 75, 
No. 29).

2. Amendment filed 7-16-76; effective thirtieth day thereafter (Register 76, 
No. 29).

3. Amendment of subsection (a) filed 4-27-79; effective thirtieth day
thereafter (Register 79, No. 17).

4. Change without regulatory effect providing more legible illustrations for
Figures V-1, V-2, V-3, V-4, V-5, V-6, V-7 and V-8 filed 3-2-2009 pursuant to 
section 100, title 1, California Code of Regulations (Register 2009, No.
10).

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