240 Spray Finishing Using Flammable and Combustible Materials
240.01 Scope
240.02 Definitions Applicable to this Section
240.03 General Requirements
240.04 Spray Booths and Rooms
240.05 Electrical and Other Sources of Ignition
224.06 Ventilation
240.07 Velocity and Air Flow Requirements
240.08 Flammable and Combustible Liquids - Storage and Handling
240.09 Protection
240.10 Operations and Maintenance
240.11 Fixed Electrostatic Apparatus
240.12 Electrostatic Hand Spraying Equipment
240.13 Drying, Curing, or Fusion Apparatus
240.14 Automobile Undercoating in Garages
240.15 Powder Coating
240.16 Organic Peroxides and Dual Component Coatings

240. SPRAY FINISHING USING FLAMMABLE AND COMBUSTIBLE MATERIALS. (7-1-97)

01. Scope: (7-1-97)

a. Spray finishing using flammable and combustible materials shall conform to all other applicable requirements of this standard, as well as the following provisions. Nothing in this standard shall be construed to prohibit better or otherwise safer conditions than specified herein. (7-1-97)

b. This section applies to flammable and combustible finishing materials when applied as a spray by compressed air, airless, or hydraulic atomization, steam, electrostatic methods, or by any other means in continuous or intermittent processes. This section also covers the application of combustible powders by powder spray guns, electrostatic powder spray guns, fluidized beds, or electrostatic fluidized beds. The section does not apply to outdoor spray application of buildings, tanks, or other similar structures, nor to small portable spraying apparatus not used repeatedly in the same location. (7-1-97)

c. Spray booths or spray rooms are to be used to enclose or confine all spray finishing operations covered by this section. (7-1-97)

02. Definitions: For definitions of other terms used in this section, see sub-section 010 of this standard. (7-1-97)

a. Aerated Solid Powders are any powdered material used as a coating material which shall be fluidized within a container by passing air uniformly from below. It is common practice to fluidize such material to form a fluidized powder bed and then dip the part to be coated into the bed in a manner similar to that used in liquid dipping. Such beds are also used as sources for powder spray operations. (7-1-97)

b. Fluidized Bed is a container holding material which is aerated from below so as to form an air-supported expanded cloud of such material through which the preheated object to be coated is immersed and transported. (7-1-97)

c. Fluidized Bed, Electrostatic, is a container holding powder coating material which is aerated from below so as to form an air supported expanded cloud of such material which is electrically charged with a charge opposite to the charge of the object to be coated; such object is transported through the container immediately above the charged and aerated materials in order to be coated. (7-1-97)

d. Minimum Maintained Velocity is the velocity of air movement which must be maintained in order to meet minimum specified requirements for health and safety. (7-1-97)

e. Spraying Area is any area in which dangerous quantities of flammable vapors or mists or combustible residues, dusts, or deposits are present due to the operation of spraying processes. (7-1-97)

f. Spray Booth is a power ventilated structure provided to enclose or accommodate a spraying operation, to confine and limit the escape of spray, vapor, and residue, and to safely conduct or direct them to an exhaust system. (7-1-97)

g. Spray Booth, Waterwash, is a spray booth equipped with a water washing system designed to minimize dusts or residues entering exhaust ducts and to permit the recovery of over-spray finishing material. (7-1-97)

h. Spray Booth., Dry, is a spray booth not equipped with a water washing system as described in Subsection d. of this section. A dry spray booth may be equipped with: distribution or baffle plates to promote an even flow of air through the booth or cause the deposit of over-spray before it enters the exhaust duct; or over-spray dry filters to minimize dusts; or over-spray dry filters to minimize dusts or residues entering exhaust ducts; or over-spray dry filter rolls designed to minimize dusts or residues entering exhaust ducts; or where dry powders are being sprayed, with powder collection systems so arranged in the exhaust to capture over-sprayed material. (7-1-97)

i. Spray-Finishing Operation are employment of methods wherein organic or inorganic materials are utilized in dispersed form for deposit on surfaces to be coated, treated, or cleaned. Such methods of deposit may involve either automatic, manual, or electrostatic deposition but do not include metal spraying or metalizing, dipping, flow coating, roller coating, tumbling, centrifuging, or spray washing and degreasing as conducted in self-contained washing and degreasing machines or systems. (7-1-97)

j. Spray Room is a room in which spray-finishing operations, not conducted in a spray booth, are performed separately from other areas. (7-1-97)

03. General Requirements: (7-1-97)

a. Respiratory protection is to meet the requirements of section 050 of this standard. (7-1-97)

04. Spray Booths and Rooms: (7-1-97)

a. Spray booths shall be substantially constructed of steel, securely and rigidly supported, or of concrete or masonry except that aluminum or other substantial noncombustible material may be used for intermittent or low volume spraying. Spray booths shall be designed to sweep air currents toward the exhaust outlet. (7-1-97)

b. The interior surfaces of spray booths and rooms shall be smooth and continuous without edges and otherwise designed to prevent pocketing of residues and facilitate cleaning and washing without injury. (7-1-97)

c. The floor surface of a spray booth or room and operator's working area, if combustible, shall be covered with noncombustible material of such character as to facilitate the safe cleaning and removal of residues. (7-1-97)

d. Distribution of baffle plates, if installed to promote an even flow of air through the booth/room or cause the deposit of over-spray before it enters the exhaust duct, shall be of noncombustible material and readily removal be or accessible on both sides for cleaning. Such plates shall not be located in exhaust ducts. (7-1-97)

e. The spraying operations except electrostatic spraying operations shall be so designed, installed, and maintained that the open face of the booth (or booth cross section during spraying operations) shall be not less than one-hundred (100) linear feet per minute. Electrostatic spraying operations may be conducted with an air velocity over the open face of the booth of not less than sixty (60) linear feet per minute, or more, depending on the volume of the finishing material being applied and its flammability and explosion characteristics. Visible gauges or audible alarm or pressure activated devices shall be installed to indicate or insure that the required air velocity is maintained. Dry spray booths equipped with a filter roll which is automatically advanced should be arranged to cause shutdown of spraying operations if the filter roll fails to advance automatically. Maintenance procedures should be established to assure replacing filter pads before excessive restriction to air-flow occurs. Filter pads should be inspected after each period of use and clogged filter pads discarded and replaced. Filter rolls shall be inspected to insure proper replacement of filter media. (7-1-97)

f. All discarded filter pads and filter rolls shall be immediately removed to a safe, well-detected location or placed in a water-filled metal container and disposed of at the close of the day's operation unless maintained completely in water. (7-1-97)

g. The location of filters in a spray booth/room shall be so as to not reduce the effective booth/room enclosure of the articles being sprayed. (7-1-97)

h. Space within the spray booth/room on the downstream and upstream sides of filters shall be protected with approved automatic sprinklers. (7-1-97)

i. Filters or filter rolls shall not be used when applying a spray material known to be highly susceptible to spontaneous heating and ignition. (7-1-97)

j. Clean filters or filter rolls shall be noncombustible or of a type having a combustibility not in excess of Class two (2) filters as listed by Underwriters' Laboratories, Inc. Filters and filter rolls shall not be alternately used for different types of coating materials, where the combination of materials may be conducive to spontaneous ignition. (7-1-97)

k. Each spray booth having a frontal area larger than nine (9) square feet shall have a metal deflector or curtain not less than two and one-half (2 1/2) inches deep installed at the upper outer edge of the booth over the opening. (7-1-97)

l. Where conveyors are arranged to carry work into or out of spray booths/rooms, the openings therefor shall be as small as practical. (7-1-97)

m. Each spray booth shall be separated from other operations by not less than three (3) feet, or by a greater distance, or by such partition or wall as to reduce the danger from juxtaposition of hazardous operations. (7-1-97)

n. Spray booths shall be so installed that all portions are readily accessible for cleaning. A clear space of not less than three (3) feet on all sides shall be kept free from storage of combustible construction. (7-1-97)

o. When Spraying areas are illuminated through glass panels or other transparent materials, only fixed lighting units shall be used as a source of illumination. Panels shall effectively isolate the spraying area from the area in which the lighting unit is located, and shall be of a noncombustible material of such a nature or so protected that breakage will be unlikely. Panels shall be so arranged that normal accumulations of residue on the exposed surface of the panel will not be raised to a dangerous temperature by radiation or conduction from the source of illumination. (7-1-97)

p. Spray booths or spray rooms are to be used to enclose or confine all spray-finishing operations. (7-1-97)

q. Spray booths shall be designed and constructed in accordance with this subsection and NFPA No. 33 for general construction specifications. For a more detailed discussion of fundamentals relating to this subject, see ANSI Z9.2. (7-1-97)

r. Lights, motors, electrical equipment, and other sources of ignition shall conform to the requirements of sub-section 240.05 of this section, section 150 of this standard, and the National Electric Code (7-1-97)

s. In no case shall combustible material be used in the construction of a spray booth or room and supply or exhaust duct connected to it. (7-1-97)

t. Unobstructed walkways shall not be less than six-point-five (6.5) feet high and shall be maintained clear of obstruction from any work location in the booth to a booth exit or open booth front. In booths where the open front is the only exit, such exits shall be not less than three (3) feet wide. In booths having multiple exits, such exits shall not be less than two (2) feet wide, provided that the maximum distance from the work location to the exit is twenty-five (25) feet or less. Where booth exits are provided with doors, such doors shall open outward from the booth. (7-1-97)

u. Over-spray filters shall be installed in a location easily accessible for inspection, cleaning, or replacement. (7-1-97)

v. Where effective means, independent of the over-spray filters, are installed which will result in design air distribution across the booth cross section, it is permissible to operate the booth without the filters in place. (7-1-97)

w. For wet or water-wash spray booths/rooms, the water-chamber enclosure within which intimate contact of contaminated air and cleaning water or other cleaning medium is maintained, if made of steel, shall be eighteen (18) gage or heavier and adequately protected against corrosion. (7-1-97)

x. Water chambers may include scrubber spray nozzles, headers, troughs, or other devices. Chambers shall be provided with adequate means for creating and maintaining scrubbing action for removal of particulate matter from the exhaust air stream. (7-1-97)

y. Collecting tanks shall be of welded steel construction or other suitable non-combustible material. If pits are used as collecting tanks, they shall be concrete, masonry, or other material having similar properties. (7-1-97)

z. Collecting tanks shall be provided with tiers, skimmer plates, or screens to prevent sludge and floating materials from entering the pump suction box. Means for automatically maintaining the proper water level shall also be provided. Fresh water inlets shall not be submerged. They shall terminate at least one pipe diameter above the safety overflow level of the tank. (7-1-97)

aa. Collecting tanks shall be so constructed as to discourage accumulation of hazardous deposits. (7-1-97)

bb. Pump manifolds, risers, and headers shall be adequately sized to insure sufficient water flow to provide efficient operation of the water chamber. (7-1-97)

cc. Spray rooms, including floors, shall be constructed of masonry, concrete, or other noncombustible material. (7-1-97)

dd. Spray rooms shall have noncombustible fire doors and shutters. (7-1-97)

ee. Spray rooms shall be adequately ventilated so that the atmosphere in the breathing zone of the operator shall be maintained in accordance with the requirements of sub-section 241.06. of this section. (7-1-97)

ff. Spray rooms used for production spray-finishing operations shall conform to the requirements for spray booths. (7-1-97)

05. Electrical and Other Sources of Ignition: (7-1-97)

a. Conformance. All electrical equipment, open flames and other sources of ignition shall conform to the requirements of this section, except as follows: Electrostatic apparatus shall conform to the requirements of sub-sections 240.11 and 240.12 of this section. Drying, curing and fusion apparatus shall conform to the requirements of sub-section 240.13 of this section. Automobile undercoating spray operations in garages shall conform to the requirements of sub-section 240.14 of this section. Powder coating equipment shall conform to the requirements of sub-section 240.15 of this section. (7-1-97)

b. There shall be no open flame or spark producing equipment in any spraying area nor within twenty (20) feet thereof, unless separated by a partition. (7-1-97)

c. Space-heating appliances, steam pipes, or hot surfaces shall not be located in a spraying area where deposits of combustible residues may readily accumulate. (7-1-97)

d. Electrical wiring and equipment shall conform to the provisions of this section and shall otherwise be in accordance with section 150 of this standard. (7-1-97)

e. Unless specifically approved for locations containing both deposits of readily ignitable residue and explosive vapors, there shall be no electrical equipment in any spraying area, whereon deposits of combustible residues may readily accumulate, except wiring in rigid conduit, in boxes, or fittings containing no taps, splices, or terminal connections. (7-1-97)

f. Electrical wiring and equipment not subject to deposits of combustible residues but located in a spraying area as herein defined shall be of explosion-proof type approved for Class I, Group D locations and shall otherwise conform to the provisions of section 150 of this standard, for Class I, Division I Locations. Electrical wiring, motors, and other equipment outside of but within twenty (20) feet of any spraying area, and not separated therefrom by partitions shall not produce sparks under normal operating conditions and shall otherwise conform to the provisions of section 150 of this standard, for Class I, Division 2 Hazardous Locations. (7-1-97)

g. Electric lamps outside of but within twenty (20) feet of any spraying area, and not separated therefrom by a partition, shall be totally enclosed to prevent the falling of hot particles and shall be protected from mechanical injury by suitable guards or by location. (7-1-97)

h. Portable electric lamps shall not be used in any spraying area during spraying operations. Portable electric lamps, if used during cleaning or repairing operations, shall be of the type approved for hazardous Class I locations. (7-1-97)

i. All metal parts of spray booths, exhaust ducts, and piping systems conveying flammable or combustible liquids or aerated solids shall be properly electrically grounded in an effective and permanent manner. (7-1-97)

j. Airless high-fluid pressure spray guns and any conductive object being sprayed shall be properly electrically grounded. (7-1-97)

06. Ventilation: (7-1-97)

a. Ventilation and exhaust systems shall be in accordance with NFPA 91 where applicable and shall also conform to the provisions of this section and section 300 of this standard. (7-1-97)

b. Ventilation shall be provided in accordance with provisions of NFPA No. 33, and in accordance with the following: Where a fan plenum is used to equalize or control the distribution of exhaust air movement through the booth, it shall be of sufficient strength or rigidity to withstand the differential air pressure or other superficially imposed loads for which the equipment is designed and also to facilitate cleaning. Construction specifications shall be at least equivalent to those of sub-section 240.06.c. of this section. (7-1-97)

c. All spraying areas shall be provided 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. Mechanical ventilation shall be kept 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. (7-1-97)

d. Each spray booth shall 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 eighteen (18) square feet may have a common exhaust. If more than one (1) fan serves one (1) booth, all fans shall be so interconnected that one (1) fan cannot operate without all fans being operated. Exhaust discharge shall be so directed that it is not reintroduced into buildings through air intakes of heating/ventilation equipment. (7-1-97)

e. 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 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 shall 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 shall be of the self lubricating type, or lubricated from the outside of the duct. (7-1-97)

f. Clean fresh air, free from contamination from adjacent industrial exhaust systems, chimneys, stacks, or vents, shall be supplied to a spray booth or room in quantities equal to the volume of air exhausted through the spray booth/room. (7-1-97)

g. Where a spray booth or room receives make-up air through self-closing doors, dampers, or louvers, they shall be fully open at all times when the booth or room is in use for spraying. The velocity of air through such doors, dampers, or louvers shall not exceed two-hundred (200) feet per minute. If the fan characteristics are such that the required air flow through the booth will be provided, higher velocities through the doors, dampers, or louvers may be used. (7-1-97)

h. Where the air supply to a spray booth or room is filtered, the fan static pressure shall be calculated on the assumption that the filters are dirty to the extent that they require cleaning or replacement. The rating of filters shall be governed by test date supplied by the manufacturer of the filter. A pressure gage shall be installed to show the pressure drop across the filters. This gage shall be marked to show the pressure drop at which the filters require cleaning or replacement. Filters shall be replaced or cleaned whenever the pressure drop across them becomes excessive or whenever the air flow through the face of the booth falls below that specified in Table 240.07-B. (7-1-97)

i. Means for heating make-up air to any spray booth or room, before or at the time spraying is normally performed, shall be provided in all places where the outdoor temperature may be expected to remain below fifty-five (55) degrees Fahrenheit for appreciable periods of time during the operation of the booth except where adequate and safe means of radiant heating for all operating personnel affected is provided. The replacement air during the heating seasons shall be maintained at not less than sixty-five (65) degrees Fahrenheit at the point of entry into the spray booth or spray room. When otherwise unheated make-up air would be at a temperature of more than ten (10) degrees Fahrenheit below room temperature, its temperature shall be regulated as provided in ANSI Z9.2. (7-1-97)

j. As an alternative to an air replacement system complying with the preceding subsection, general heating of the building in which the spray room or booth is located may be employed provided that all occupied parts of the building are maintained at not less than sixty-five (65) degrees Fahrenheit when the exhaust system is in operation or the general heating system supplemented by other sources of heat may be employed to meet this requirement. (7-1-97)

k. No means of heating make-up air shall be located in a spray booth/room. (7-1-97)

l. Where make-up air is heated by coal or oil, the products of combustion shall not be allowed to mix with the makeup air, and the products of combustion shall be conducted outside the building through a flue terminating at a point remote from all points where make-up air enters the building. (7-1-97)

m. Where make-up air is heated by gas, and the products of combustion are not mixed with the make-up air but are conducted through an independent flue to a point outside the building remote from all points where make-up air enters the building, it is not necessary to comply with sub-section 240.06.i. of this section. (7-1-97)

n. Where make-up air to any manually operated spray booth or room is heated by gas and the products of combustion are allowed to mix with the supply air, the following precautions shall be taken: The gas must have a distinctive and strong enough odor to warn workers in a spray booth or room of its presence if in an unburned state in the make-up air. The maximum rate of gas supply to the make-up air heater burners must not exceed that which would yield in excess of two-hundred (200) p.p.m. (parts per million) of carbon monoxide or two-thousand (2,000) p.p.m. of total combustible gases in the mixture if the unburned gas upon the occurrence of flame failure were mixed with all of the make-up air supplied. A fan must be provided to deliver the mixture of heated air and products of combustion from the plenum chamber housing the gas burners from the spray booth or room. (7-1-97)

o. Inlet or supply ductwork used to transport makeup air to spray booths/rooms or surrounding areas shall be constructed of noncombustible materials. (7-1-97)

p. If negative pressure exists within inlet ductwork, all seams and joints shall be sealed if there is a possibility of infiltration of harmful quantities of noxious gases, fumes, or mists from areas through which ductwork passes. (7-1-97)

q. Inlet ductwork shall be sized in accordance with volume flow requirements and provide design air requirements at the spray booth. (7-1-97)

r. Inlet ductwork shall be adequately supported throughout its length to sustain at least its own weight plus any negative pressure which is exerted upon it under normal operating conditions. (7-1-97)

s. Electric motors driving exhaust fans shall not be placed inside booths or ducts. (7-1-97)

t. Belts shall not enter the duct or booth unless the belt and pulley within the duct or booth are thoroughly enclosed. (7-1-97)

u. Exhaust ducts shall be constructed of steel and shall be substantially supported. Exhaust ducts without dampers are preferred; however, if dampers are installed, they shall be maintained so that they will be in a full open position at all times the ventilating system is in operation. (7-1-97)

v. Exhaust ductwork shall be adequately supported throughout its length to sustain its weight plus any normal accumulation in it's interior during normal operating conditions and any negative pressure exerted upon it. (7-1-97)

w. Exhaust ductwork shall be sized in accordance with good design practice which shall include consideration of fan capacity, length of duct, number of turns and elbows, variation in size, volume, and character of materials being exhausted. (7-1-97)

x. Exhaust ducts shall be protected against mechanical damage and have a clearance from unprotected combustible construction or other combustible material of not less than eighteen (18) inches. (7-1-97)

y. If combustible construction is provided with the following protection applied to all surfaces within eighteen (18) inches, clearances may be reduced to the distances indicated: (7-1-97)

i. Twenty-eight (28) gage sheet metal on one-fourth (1/4) inch cement mill board - twelve (12) inches; (7-1-97)

ii. Twenty-eight (28) gage sheet metal on one-eighth (1/8) inch cement mill board space out one (1) inch on noncombustible spacers - nine (9) inches; (7-1-97)

iii. Twenty-two (22) gage sheet metal on one (1) inch rockwool batts reinforced with wire mesh or the equivalent - three (3) inches. (7-1-97)

iv. Where ducts are protected with an approved automatic sprinkler system, properly maintained, the clearance required in sub-section 240.06.s. of this section may be reduced to six (6) inches. (7-1-97)

z. Longitudinal joints in sheet steel ductwork shall be either lock-seamed riveted, or welded. For other than steel construction, equivalent securing of joints shall be provided. (7-1-97)

aa. Circumferential joints in ductwork shall be substantially fastened together and lapped in the direction of air-flow. At least every fourth joint shall be provided with connecting flanges, bolted together, or of equivalent fastening security. (7-1-97)

bb. Unless spray booth exhaust duct terminal is from a water-wash spray booth, the terminal discharge point shall be not less than six (6) 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 twenty-five (25) feet. (7-1-97)

cc. 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. When ducts pass through firewalls, they shall be provided with automatic fire dampers on both sides of the wall, except that three-eighth (3/8) inch steel plates may be used in lieu of automatic fire dampers for ducts not exceeding eighteen (18) inches in diameter. (7-1-97)

dd. Air exhaust from spray operations shall not be directed so that it will contaminate makeup air being introduced into the spraying area or other ventilating intakes, nor directed so as to create a nuisance. Air exhausted from spray operations shall not be recirculated. (7-1-97)

ee. Ductwork used for ventilating and processes covered in this section shall not be connected to ducts ventilating any other process or any chimney or flue used for conveying any products of combustion. (7-1-97)

ff. When necessary to facilitate cleaning, exhaust ducts shall be provided with an ample number of access doors. Inspection or clean-out doors shall be provided for every nine (9) to twelve (12) feet of running length for ducts up to twelve (12) inches in diameter, but the distance between clean-out doors may be greater for larger pipes. A clean-out door or doors shall be provided for servicing the fan, and where necessary, a drain shall be provided. (7-1-97)

gg. Air intake openings to rooms containing spray finishing operations shall be adequate for the efficient operation of exhaust fans and shall be so located as to minimize the creation of dead air pockets. (7-1-97)

hh. Freshly sprayed articles shall be dried only in spaces provided with adequate ventilation to prevent the formation of explosive vapors. In the event adequate and reliable ventilation is not provided such drying spaces shall be considered a spraying area. (7-1-97)

07. Velocity and Air Flow Requirements: (7-1-97)

a. Except where a spray booth/room has an adequate air replacement system, the velocity of air into all openings of a spray booth/room shall be not less than that specified in Table 240.07-A for the operating conditions specified. An adequate air replacement system is one which introduces replacement air upstream or above the object being sprayed and is so designed that the velocity of air in the booth/room cross section is not less than that specified in Table 240.07-A when measured upstream or above the object being sprayed. (7-1-97)