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Subchapter 7. General Industry Safety Orders
Group 20. Flammable Liquids, Gases and Vapors
Article 137. Spray Coating Operations

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§5450. Ventilation.

(a) Ventilation requirements shall conform to the provisions of Section 5153 and 5143 and this Section.

(b) Except as permitted in Section 5460, each spray booth shall have an independent exhaust duct system discharging to the building exterior. Multiple cabinet spray booths in which identical spray finishing material is used with a combined frontal area of more than eighteen square feet shall not have a common exhaust.

(c) The fan rotating element shall be nonferrous or nonsparking or the casing shall consist of or be lined with such material. There shall be ample clearance between the fan rotating element and fan casing to avoid a fire by friction, necessary allowance being made for ordinary expansion and loading to prevent contact between moving parts and the duct or fan housing. Fan blades shall be mounted on a shaft sufficiently heavy to maintain proper alignment even when the blades of the fan are heavily loaded, the shaft preferably to have bearings outside the duct and booth. All bearings shall be of the self-lubricating type, or lubricated from outside the duct.

(d) Electric motors driving exhaust fans shall not be placed inside booths or ducts.

(e) Belts shall not enter duct or booth unless belt and pulley within the duct or booth are completely enclosed.

(f) Where ductwork passes through a combustible roof or wall, the roof or wall shall be protected at the point of penetration by open space or fire resistive material between the duct and the roof or wall.

(g) When ducts pass through firewalls, they shall be provided with automatic fire dampers on both sides of the wall, except that 3/8-inch steel plates may be used in lieu of automatic fire dampers for ducts not exceeding 18 inches in diameter.

(h) Exhaust ducts shall be constructed of steel and shall be substantially supported. If dampers are installed, they shall be maintained so that adequate airflow is maintained at all times the ventilating system is in operation. When spray booths are not in use and it is necessary to shut off ducts, noncombustible removable covers completely closing ducts may be used.

(i) Exhaust ducts shall be protected against mechanical damage and have a clearance from unprotected combustible construction or other combustible material of not less than 18 inches, except if combustible construction is provided with the following protection applied to all surfaces within 18 inches, clearances may be reduced to the distance indicated:

(1) 28 gauge sheet metal on 1/4-inch asbestos mill

board or equivalent.................................. 12 inches

(2) 28 gauge sheet metal on 1/8-inch asbestos mill

board spaced out one-inch on noncombustible spacers

or equivalent......................................... 9 inches

(3) 22 gauge sheet metal on 1-inch rockwool bats

reinforced with wire mesh or the equivalent........... 3 inches

(4) Where ducts are protected with an approved automatic sprinkler system, properly maintained; the clearance may be reduced to 6 inches.

(j) The spray booth exhaust discharge point shall be not less than six feet from any combustible exterior wall or roof nor discharge in the direction of any combustible construction or unprotected opening in any noncombustible exterior wall within 25 feet.

(k) Freshly sprayed articles shall be dried only in spaces provided with adequate ventilation to prevent the accumulation of flammable vapors. In the event adequate and reliable ventilation is not provided such drying spaces shall be considered a spraying area.

NOTE: Authority cited: Section 142.3, Labor Code. Reference: Section 142.3, Labor Code.


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

2. Amendment of subsections (b), (c) and (k) filed 12-5-86; effective thirtieth day thereafter (Register 86, No. 51).

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