Los Angeles County Municipal Code Part VIII Supplement (CA)

APPENDIX A TABLES OPEN SURFACE TANKS—GENERAL DESIGN FACTORS

Table I. DETERMINATION OF GAS, VAPOR OR MIST HAZARD POTENTIAL*
Maximum Acceptable Concentration
Hazard Potential	Gas & Vapor	Mist	Flash Point
A	0-100 ppm	0-0.1 mg/M 3	under 100 F.
B	101-500 ppm	0.101-0.5 mg/M 3	100*200 F.
C	Over 500 ppm	over 0.5 mg/M 3	over 200 F.
* Note: "Hazard Potential" is based upon either maximum acceptable concentration or flash point, whichever produces the highest hazard potential.

Table II. DETERMINATION OF RATE OF GAS VAPOR OR MIST EVOLUTION
Rate	Temperature of liquid degrees F.	Degrees below boiling point degrees F.	Relative Evaporation (time for 100% evaporation)	Gassing
1	over 200	0-20	Fast (0-3 hrs.)	High
2	150-200	21-50	Medium (3-12 hrs.)	Medium
3	94-149	51-100	Slow (12-50 hrs.)	Low
4	under 94	over 100	Nil (over 50 hrs.)	Nil

Table III. MINIMUM CAPTURE VELOCITY (FPM) FOR UNDISTURBED LOCATIONS
	Enclosing Hood		Canopy Hoods
Class I (See Tables I & II)	One open side	Two open sides	Lateral Exhaust	Three open sides	Four open sides
A-1,A-2,B-l	75	100	100	125	175
A-3,B-2,C-1	65	90	75	100	150
B-3, C-2	50	75	50	75	125
A4, B-4, C-4	Adequate general room ventilation sufficient

Use of Tables I, II and III.

Classify open surface tank operations by (a) hazard potential (letter designation A to C from Table 1 and (b) rate of gas, vapor or mist evolution (number designation 1 to 4 from Table II).

(a)

Determine class of open surface tank operations by (1) the substance(s), which may be released into the atmosphere and (2) the nature of such substance(s). When more than one substance is involved, base the class of operation on the substance having the highest hazard potential.

(b)

Determine rate of gas, vapor or mist evolution (1 to 4 from Table II.)

Reference for "Rate of Gassing" is Table 5-5-2, Appendix Industrial Ventilation, American Conference of Governmental Hygienists, Ninth Edition, 1966.

Design of local exhaust ventilation systems should conform to the most hazardous condition that might occur, i.e., an operation shall be classified according to the highest hazard potential (Table I) and highest rate of evolution (Table II) that might occur—use strictest criteria in each table for determining classification.

Table IV. MINIMUM CAPTURE VELOCITY FOR DUST CONTROL
Condition of dispersion of contaminant Minimum capture velocity (FPM)
Released with practically no velocity into quiet air	50
Released at low velocity into moderately still air	100
Active generation into zone of rapid air motion	200
Released at high initial velocity into zone of rapid air motion	300

Table V. MINIMUM CONVEYING VELOCITY
Material Conveyed	Minimum conveying velocity in ducts (FPM)
Vapor, gases, fumes, very fine dusts	1500
Average industrial dusts	3500
Coarse particles, heavy loads, moist	4500

APPENDIX B REFERENCE LIST

INDUSTRIAL VENTILATION—A MANUAL OF RECOMMENDED PRACTICE, published by the American Conference of Governmental Industrial Hygienists, Ninth edition, 1966.

METAL FINISHING GUIDEBOOK, published by Finishing Publications, Inc., 1960.

GUIDE TO PRECAUTIONARY LABELING OF HAZARDOUS CHEMICALS, Manufacturing Chemists' Association, Inc., Sixth edition, 1961.

"Proposed Revision to the 1955 American Standard Minimum Requirements for Sanitation in Places of Employment"—For California, Metropolitan Directors of Environmental Sanitation, March 1959.

GENERAL INDUSTRIAL SAFETY ORDER'S, State of California, Department of Industrial Relations.

EXHAUST HOODS, J. M. Dalla Valle, Industrial Press, New York, New York, 1952.

ACCIDENT PREVENTION MANUAL FOR INDUSTRIAL OPERATIONS, National Safety Council, 4th edition, Chicago, Illinois, 1959.

Federal Hazardous Substances Labeling Act.

California Hazardous Substances Labeling Act (excerpt from the California Health and Safety Coded.

Manuals of Stand and Recommended Practice Nos. C-1, C-2, D-31 and D-40, Manufacturing Chemists' Association, Inc.

Threshold Limit Values for 1967 (adopted at the 29th Annual Meeting of the American Conference of Governmental Industrial Hygienists).

Recommended Lighting Standards, Illuminating Engineering Society, September 1962.

United States of America Standards Institute Safety Code Z2-1-1959.