Los Angeles Municipal Code § 57.2404 Spray Finishing

Section 2404 of the CFC is hereby adopted in its entirety with the following exceptions, modifications, and additions.

All combustible flooring under and adjacent to spray booths or spray tunnels shall be protected with a covering of noncombustible material so installed as to prevent the combustible flooring from coming into contact with the flammable liquids used in the spraying process, and of such a nature as to facilitate the safe cleaning and removal of residues.

No heating device shall be located, installed, maintained or used in any spray room. For comfort of persons working within the spray room or spray booth, heating appliances of indirect type may be installed on the outside of such booths or rooms for the purpose of introducing heat inside thereof, provided the temperature does not exceed 120°F at the warm air inlet to the booth or tunnel and that location and arrangement of the heating appliance and the method of heat introduction into said room is first approved.

Exhaust ducts shall be in accordance with Sections 57.2404.7.9.1 through 57.2404.7.9.6.

Every duct or pipe shall be constructed of galvanized metal sheets in accordance with the provisions of Table 57.2404.7.9.1.

TABLE 57.2404.7.9.1

SPRAY EXHAUST DUCTS – GAUGE OF METAL

Duct Cross-Sectional Dimension in Inches Gauge of Duct Metal
Up to 8 24
Over 8 inches to 18 22
Over 18 inches to 30 20
Over 30 18

All seams in any duct or pipe shall be made tight by crimping or other equally efficient manner without the use of solder or combustible materials, and all sections shall be securely joined.

Exhaust ducts shall have a clearance from unprotected combustible construction or other combustible material of not less than 18 inches. This distance may be reduced if protection is provided for all combustible surfaces within 18 inches according to the following schedule:

1. 28 gauge sheet metal on 1/4-inch insulating millboard 12 inches.

2. 28 gauge sheet metal on 1/8-inch insulating millboard spaced out 1 inch on noncombustible spacers 9 inches.

3. 22 gauge sheet metal on 1-inch rockwool bats reinforced with wire mesh or the equivalent 3 inches.

4. Any other approved material of equal of greater fire-resistance.

Ducts or pipes may be separated from combustible material by a ventilated collar which provides a clear air space equal to one-half the diameter of the duct, but in no event shall such collar provide less than 3-inch air space, and such collar shall extend not less than 12 inches above and below such combustible material.

Every branch duct or pipe shall be connected to the main duct or pipe at an angle not exceeding 45 degrees measured from the centerline of the main duct or pipe. Every bend, turn or elbow in any duct or pipe shall be constructed so as not to reduce the cross sectional area of the duct or pipe. Every change in cross section of any such duct or pipe shall be by means of a transition fitting having a slope or taper of not more than 1 inch for each 4 inches in length of the said duct or pipe.

Exhaust ducts shall be designed to provide sufficient air transport velocity to prevent the over-spray from settling in the duct.