Washington Administrative Code › Title 296 - Labor and Industries, Department of › Chapter 296-24 - General safety and health standards › Part E - HAZARDOUS MATERIALS, FLAMMABLE LIQUIDS, SPRAY FINISHING › Hazardous Materials › Section 296-24-37007 - Ventilation

Current through Register Vol. 24-14, July 15, 2024
(1)
Conformance.
Ventilating and exhaust systems must be in accordance
				  with the Standard for Blower and Exhaust Systems for Vapor Removal, NFPA No.
				  91-1961, where applicable and must also conform to the provisions of this
				  section.
(2)
General.
You must provide all spraying areas with mechanical ventilation adequate to
				  remove flammable vapors, mists or powders to a safe location and to confine and
				  control combustible residues so that life is not endangered. You must keep
				  mechanical ventilation in operation at all times while spraying operations are
				  being conducted and for a sufficient time thereafter to allow vapors from
				  drying coated articles and drying finishing material residue to be
				  exhausted.
(3)
Independent
				  exhaust.
Each spray booth must have an independent exhaust duct system
				  discharging to the exterior of the building, except that multiple cabinet spray
				  booths in which identical spray finishing material is used with a combined
				  frontal area of not more than 18 square feet may have a common exhaust. If more
				  than one fan serves one booth, all fans must be interconnected so that one fan
				  cannot operate without all fans being operated.
(4)
Fan-rotating element.
The
				  fan-rotating element must be nonferrous or nonsparking or the casing must
				  consist of or be lined with such material. There must be ample clearance
				  between the fan-rotating element and the 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
				  must be mounted on a shaft sufficiently heavy to maintain perfect alignment
				  even when the blades of the fan are heavily loaded, the shaft preferably to
				  have bearings outside the duct and booth. All bearings must be of the
				  self-lubricating type, or lubricated from the outside duct.
(5)
Electric motors.
You must
				  not place electric motors driving exhaust fans inside booths or ducts. See also
				  WAC 296-24-37005.
(6)
Belts.
Belts must not enter
				  the duct or booth unless the belt and pulley within the duct or booth are
				  thoroughly enclosed.
(7)
Exhaust ducts.
Exhaust ducts must be constructed of steel and must
				  be substantially supported. Exhaust ducts without dampers are preferred;
				  however, if dampers are installed, you must maintain them so that they will be
				  in a full open position at all times the ventilating system is in operation.
(a) You must protect exhaust ducts against
				  mechanical damage and have a clearance from unprotected combustible
				  construction or other combustible material of not less than 18
				  inches.
(b) If combustible
				  construction is provided with the following protection applied to all surfaces
				  within 18 inches, clearances may be reduced to the distances indicated:
(i) 8- gauge sheet metal on 1/4-inch 12
				  inches. asbestos mill board.
(ii)
				  28- gauge sheet metal on 1/8-inch 9 inches. asbestos mill board spaced out 1
				  inch on noncombustible spacers.
(iii) 22- gauge sheet metal on 1-inch 3
				  inches. rockwool batts reinforced with wire mesh or the equivalent.
(iv) Where ducts are protected with an
				  approved automatic sprinkler system, properly maintained, the clearance
				  required in (7)(a) of this section may be reduced to 6 inches.