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Article 516

Spray Application, Dipping, Coating, and Printing Processes Using Flammable or Combustible Materials

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Part I. General

516.1 Scope. This article covers the regular or frequent appli‐ cation of flammable liquids, combustible liquids, and combusti‐ ble powders by spray operations and the application of flammable liquids or combustible liquids at temperatures above their flashpoint by spraying, dipping, coating, printing, or other means.

Informational Note No. 1: For further information regarding safeguards for these processes, such as fire protection, posting of warning signs, and maintenance, see NFPA 33-2016, Standard for Spray Application Using Flammable and Combustible Materials, and NFPA 34-2015, Standard for Dipping, Coating, and Printing Processes Using Flammable or Combustible Liquids. For additional informa‐ tion regarding ventilation, see NFPA 91 -2015, Standard for Exhaust Systems for Air Conveying of Vapors, Gases, Mists, and Partic‐ ulate Solids.

Spray Area. Any fully enclosed, partly enclosed, or unenclosed

image

Informational Note: Unenclosed spray areas are locations

outside of buildings or are localized operations within a larger room or space. Such are normally provided with some local vapor extraction/ventilation system. In automated operations, the area limits are the maximum area in the direct path of spray operations. In manual operations, the area limits are the maxi‐ mum area of spray when aimed at 90 degrees to the application surface.

area in which dangerous quantities of flammable or combusti‐ ble vapors, mists, residues, dusts, or deposits are present due to the operation of spray processes, including (1) any area in the direct path of a spray application process; (2) the interior of a spray booth, spray room, or limited finishing workstation, as herein defined; (3) the interior of any exhaust plenum, elimi‐ nator section, or scrubber section; (4) the interior of any exhaust duct or exhaust stack leading from a spray application process; (5) the interior of any air recirculation path up to and including recirculation particulate filters; (6) any solvent concentrator (pollution abatement) unit or solvent recovery (distillation) unit; and (7) the inside of a membrane enclosure. The following are not part of the spray area: (1) fresh air make- up units; (2) air supply ducts and air supply plenums; (3) recir‐ culation air supply ducts downstream of recirculation particulate filters; and (4) exhaust ducts from solvent concen‐ trator (pollution abatement) units. [33:3.3.2.3]

Spray Booth. A power-ventilated enclosure for a spray applica‐ tion operation or process that confines and limits the escape of the material being sprayed, including vapors, mists, dusts, and

residues that are produced by the spraying operation and conducts or directs these materials to an exhaust system. [33:3.3.15]

image

610 mm (2 ft)

Informational Note: A spray booth is an enclosure or insert

within a larger room used for spray/coating/dipping applica‐ tions. A spray booth can be fully enclosed or have open front or face and can include separate conveyor entrance and exit. The spray booth is provided with a dedicated ventilation exhaust with supply air from the larger room or from a dedicated air supply.

915 mm

(3 ft)

460 mm

(18 in.)

Spray Room. A power-ventilated fully enclosed room used exclusively for open spraying of flammable or combustible materials. [33:3.3.16]

             3050 mm                            3050 mm               

Unenclosed Spray Area. Any spray area that is not confined by a limited finishing workstation, spray booth, or spray room, as herein defined. [33:3.3.2.3.2]

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Part II. Open Containers

(10 ft)

image

Class I, Division 1 or Zone 0 (e.g., vapor space in container)

image Class I, Division 1 or Zone 1 image Class I, Division 2 or Zone 2

(10 ft)

Pit or trench

  1. Area Classification. For open containers, supply containers, waste containers, spray gun cleaners, and solvent distillation units that contain Class I liquids that are located in ventilated areas, area classification shall be in accordance with the following:
    1. The area within 915 mm (3 ft) in all directions from any such container or equipment and extending to the floor or grade level shall be classified as Class I, Division 1 or Class I, Zone 1, whichever is applicable. [33:6.5.5.1]
    2. The area extending 610 mm (2 ft) beyond the Division 1 or Zone 1 location shall be classified as Class I, Division 2 or Class I, Zone 2, whichever is applicable. [33:6.5.5.1]
    3. The area extending 1525 mm (5 ft) horizontally beyond the area described in 516.4(2) up to a height of 460 mm (18 in.) above the floor or grade level shall be classified as Class I, Division 2 or Class I, Zone 2, whichever is applica‐ ble. [33:6.5.5.1]
    4. The area inside any tank or container shall be classified as Class I, Division 1 or Class I, Zone 0, whichever is applica‐ ble. [33:6.5.5.1]
    5. Sumps, pits, or below grade channels within 3.5 m (10 ft) horizontally of a vapor source shall be classified as Class I, Division 1 or Zone 1. If the sump, pit, or channel extends beyond 3.5 m (10 ft) from the vapor source, it shall be provided with a vapor stop or it shall be classified as Class I, Division 1 or Zone 1 for its entire length.
    For the purposes of electrical area classification, the Division system and the Zone system shall not be intermixed for any given source of release. [33:6.2.3]Electrical wiring and utilization equipment installed in these areas shall be suitable for the location, as shown in Figure 516.4. [33:6.5.5.2]
    Part III. Spray Application Processes
  2. Area Classification. For spray application processes, the area classification is based on quantities of flammable vapors, combustible mists, residues, dusts, or deposits that are present or might be present in quantities sufficient to produce ignita‐ ble or explosive mixtures with air.N FIGURE 516.4 Electrical Area Classification for Class I Liquid Operations Around Open Containers, Supply Containers, Waste Containers, Spray Gun Cleaners, and Solvent Distillation Units. [33:Figure 6.5.5.2]
    1. Zone Classification of Locations.
      1. Classification of Locations. The Zone system of electrical area classification shall be applied as follows:
        1. The inside of closed containers or vessels shall be consid‐ ered a Class I, Zone 0 location.
        2. A Class I, Division 1 location shall be permitted to be alternatively classified as a Class I, Zone 1 location.
        3. A Class I, Division 2 location shall be permitted to be alternatively classified as a Class I, Zone 2 location.
        4. A Class II, Division 1 location shall be permitted to be alternatively classified as a Zone 21 location.
        5. A Class II, Division 2 location shall be permitted to be alternatively classified as a Zone 22 location. [33:6.2.2]
        1. Classification Systems. For the purposes of electrical area classification, the Division system and the Zone system shall not be intermixed for any given source of release. [33:6.2.3]In instances of areas within the same facility classified sepa‐ rately, Class I, Zone 2 locations shall be permitted to abut, but not overlap, Class I, Division 2 locations. Class I, Zone 0 or Zone 1 locations shall not abut Class I, Division 1 or Division 2 locations. [33:6.2.4]
        2. Equipment. Open flames, spark-producing equipment or processes, and equipment whose exposed surfaces exceed the autoignition temperature of the material being sprayed shall not be located in a spray area or in any surrounding area that is classified as Division 2, Zone 2, or Zone 22. [33:6.2.5]
        Exception: This requirement shall not apply to drying, curing, or fusing apparatus.Any utilization equipment or apparatus that is capable of producing sparks or particles of hot metal and that is located above or adjacent to either the spray area or the surrounding Division 2, Zone 2, or Zone 22 areas shall be of the totally enclosed type or shall be constructed to prevent the escape of sparks or particles of hot metal. [33:6.2.6]
    2. Class I, Division 1 or Class I, Zone 0 Locations. The inte‐ rior of any open or closed container or vessel of a flammable liquid shall be considered Class I, Division 1, or Class I, Zone 0, as applicable:Informational Note: For additional guidance, see Chapter 6 of NFPA 33-2016, Standard for Spray Application Using Flammable or Combustible Materials.
    3. Class I, Division 1; Class I, Zone 1; Class II, Division 1; or Zone 21 Locations. The following spaces shall be considered Class I, Division 1; Class I, Zone 1; Class II, Division 1; or Zone 21 locations, as applicable:
      1. The interior of spray booths and rooms except as specifi‐ cally provided in 516.5(D).
      2. The interior of exhaust ducts.
      3. Any area in the direct path of spray operations.
      4. Sumps, pits, or below grade channels within 7620 mm (25 ft) horizontally of a vapor source. If the sump, pit, or channel extends beyond 7620 mm (25 ft) from the vapor source, it shall be provided with a vapor stop or it shall be classified as Class I, Division 1 for its entire length. [34:6.4.1]
      5. All space in all directions outside of but within 900 mm
        Spray area
        imageimage3050 mm(10 ft)Spray areaTOP (PLAN)
        FRONT (ELEVATION)
        6100 mm(20 ft)(3 ft) of open containers, supply containers, spray gun cleaners, and solvent distillation units containing flamma‐ ble liquids.
      6. For limited finishing workstations, the area inside the curtains or partitions. [See Figure 516.5(D)(5).]
    4. Class I, Division 2; Class I, Zone 2; Class II, Division 2; or Zone 22 Locations. The spaces listed in 516.5(D)(1) through (D)(5) shall be considered Class I, Division 2; Class I, Zone 2; Class II, Division 2; or Zone 22 as applicable.
      1. Unenclosed Spray Processes. Electrical wiring and utiliza‐ tion equipment located outside but within 6100 mm (20 ft)Class I, Division 1; Class I, Zone 1; Class II, Division 1; or Zone 21imageimageClass I, Division 2; Class I, Zone 2; Class II, Division 2; or Zone 22
        N FIGURE 516.5(D)(1) Electrical Area Classification for Unenclosed Spray Areas. [33:Figure 6.5.1]horizontally and 3050 mm (10 ft) vertically of an enclosed spray area and not separated from the spray area by partitions extending to the boundaries of the area designated as Division 2, Zone 2 or Zone 22 in Figure 516.5(D)(1) shall be suitable for Class I, Division 2; Class I, Zone 2; Class II, Division 2; or Zone 22 locations, whichever is applicable. [33:6.5.1] [See Figure 516.5(D)(1).]
      2. Closed-Top, Open-Face, and Open-Front Spray Booths and Spray Rooms. If spray application operations are conducted within a closed-top, open-face, or open-front booth or room, as shown in Figure 516.5(D)(2), any electrical wiring or utiliza‐ tion equipment located outside of the booth or room but within 915 mm (3 ft) of any opening shall be suitable for Class I, Division 2; Class I, Zone 2; Class II, Division 2; or Zone 22 locations, whichever is applicable. The Class I, Divi‐ sion 2; Class I, Zone 2; Class II, Division 2; or Zone 22 locations shown in Figure 516.5(D)(2) shall extend from the edges of the open face or open front of the booth or room.915 mmimage(3 ft) radius
        image915 mm(3 ft) radius915 mm(3 ft) radius915 mm (3 ft) radius915 mm(3 ft) radius915 mm (3 ft) radiusimage915 mm (3 ft) radius
        ConveyorOpen openingface
      3. Open-Top Spray Booths. For spraying operations conduc‐ ted within an open top spray booth, the space 915 mm (3 ft) vertically above the booth and within 915 mm (3 ft) of other booth openings shall be considered Class I, Division 2; Class I, Zone 2; Class II, Division 2; or Zone 22 whichever is applicable. [33:6.5.3]N FIGURE 516.5(D)(2) Class I, Division 2; Class I, Zone 2; Class II, Division 2; or Zone 22 Locations Adjacent to a Closed Top, Open Face, or Open Front Spray Booth or Room. [33:Figure 6.5.2]
      4. Enclosed Spray Booths and Spray Rooms. For spray appli‐ cation operations confined to an enclosed spray booth or room, electrical area classification shall be as follows:
    1. The area within 915 mm (3 ft) of any opening shall be classified as Class I, Division 2; Class I, Zone 2; Class II, Division 2; or Zone 22 locations, whichever is applicable, as shown in Figure 516.5(D)(4).
    2. Where automated spray application equipment is used, the area outside the access doors shall be unclassified provided the door interlock prevents the spray applica‐ tion operations when the door is open.
    3. Where exhaust air is permitted to be recirculated, both of the following shall apply:
      1. The interior of any recirculation path from the secon‐ dary particulate filters up to and including the air supply plenum shall be classified as Class I, Division 2; Class I, Zone 2; Class II, Division 2; or Zone 22 loca‐ tions, whichever is applicable.
      2. The interior of fresh air supply ducts shall be unclassi‐ fied.
    4. Where exhaust air is not recirculated, the interior of fresh air supply ducts and fresh air supply plenums shall be unclassified.[33:6.5.4]
    5. Limited Finishing Workstations.
    (a) For limited finishing workstations, the area inside the 915 mm (3 ft) space horizontally and vertically beyond the volume enclosed by the outside surface of the curtains or parti‐ tions shall be classified as Class I, Division 2; Class I, Zone 2; Class II, Division 2; or Zone 22, as shown in Figure 516.5(D) (5).drying apparatus if the air temperature in the limited finishing workstation exceeds the maximum discharge-air temperature allowed by the standard that the heater is listed to or 93°C (200°F), whichever is less. [33:14.3.7.1]
    1. A means shall be provided to show that the limited finishing workstation is in the drying or curing mode of opera‐ tion and that the limited finishing workstation is to be unoccu‐ pied. [33:14.3.7.2]
    2. Any containers of flammable or combustible liquids shall be removed from the limited finishing workstation before the drying apparatus is energized. [33:14.3.7.3]
    3. Portable spot-drying, curing, or fusion apparatus shall be permitted to be used in a limited finishing workstation, provided that it is not located within the hazardous (classified) location defined in 14.3.5 of NFPA 33 when spray application operations are being conducted. [33:14.3.8]
    4. Recirculation of exhaust air shall be permitted when the provisions of 516.5(D)(4)(3) are both met. [33:14.3.9]
  3. Wiring and Equipment in Class I Locations.
    1. Wiring and Equipment — Vapors. All electrical wiring and equipment within the Class I location (containing vapor only— not residues) defined in 516.5 shall comply with the applica‐ ble provisions of Article 501 or Article 505, as applicable.(b) A limited finishing workstation shall be designed and constructed to have all of the following:
      1. A dedicated make-up air supply
      2. Curtains or partitions that are noncombustible or limited combustible
      3. A dedicated mechanical exhaust and filtration system
      4. An approved automatic extinguishing system [33:14.3.1]
      Informational Note: For limited combustible curtains or parti‐ tions see NFPA 701-2015, Standard Methods of Fire Tests for Flame Propagation of Textiles and Films.
      1. The amount of material sprayed in a limited finishing workstation shall not exceed 3.8 L (1 gal) in any 8-hour period. [33:14.3.2]
      2. Curtains or partitions shall be fully closed during any spray operations. [33:14.3.4]
      3. The equipment within the limited finishing worksta‐ tion shall be interlocked such that the spray application equip‐ ment cannot be operated unless the exhaust ventilation system is operating and functioning properly and spray application is automatically stopped if the exhaust ventilation system fails.
      4. Any limited finishing workstation used for spray appli‐ cation operations shall not be used for any operation that is capable of producing sparks or particles of hot metal or for
        915 mm(3 ft) radius
        image915 mm(3 ft) radiusExtent of Class I, Division 2;Class I, Zone 2; Class II, Division 2; or Zone 22 area915 mm(3 ft) radiusEnclosed spray booth or room(Class I, Division 1; Class I, Zone 1; Class II, Division 1; orZone 21 within)915 mm(3 ft) radiusTOP VIEW AT CEILING LEVEL
        image915 mm (3 ft) radius
        ELEVATION
        915 mm (3 ft) radius
        915 mm(3 ft) radius
        For automated spray operations See 6.5.4(2)operations that involve open flames or electrical utilization equipment capable of producing sparks or particles of hot metal. [33:14.3.6]
      5. Where industrial air heaters are used to elevate the air temperature for drying, curing, or fusing operations, a high limit switch shall be provided to automatically shut off the
      N FIGURE 516.5(D)(4) Class I, Division 2; Class I, Zone 2; Class II, Division 2; or Zone 22 Locations Adjacent to an Enclosed Spray Booth or Spray Room. [33:Figure 6.5.4]
      imageDedicated mechanical exhaust system
      Dedicated make-up air supply system
      Air supply plenumCurtains

      915 mm(3 ft)
      915 mm(3 ft)
      imageExtent of Class I, Division 2; Class I, Zone 2; Class II, Division 2 area; or Zone 22
      915 mm(3 ft)
      TOP VIEW AT CEILING LEVEL
      915 mm(3 ft)
      image915 mm(3 ft)915 mm(3 ft)image915 mm(3 ft)SIDE ELEVATION END ELEVATION
      N FIGURE 516.5(D)(5) Class I, Division 2; Class I, Zone 2; Class II, Division 2; or Zone 22 Locations Adjacent to a Limited Finishing Workstation. [33:Figure 14.3.5.1]
    2. Wiring and Equipment — Vapors and Residues. Unless specifically listed for locations containing deposits of danger‐ ous quantities of flammable or combustible vapors, mists, resi‐ dues, dusts, or deposits (as applicable), there shall be no electrical equipment in any spray area as herein defined whereon deposits of combustible residue could readily accumu‐ late, except wiring in rigid metal conduit, intermediate metal conduit, Type MI cable, or in metal boxes or fittings containing no taps, splices, or terminal connections. [33:6.4.2]
    3. Illumination. Luminaires shall be permitted to be installed as follows:
      1. Luminaires, like that shown in Figure 516.6(C)(a), that are attached to the walls or ceiling of a spray area but that are outside any classified area and are separated from the spray area by glass panels shall be suitable for use in unclassified locations. Such fixtures shall be serviced from outside the spray area. [33:6.6.1]
      2. Luminaires, like that shown in Figure 516.6(C)(a), that are attached to the walls or ceiling of a spray area; that are separated from the spray area by glass panels and that are located within a Class I, Division 2; a Class I, Zone 2; a Class II, Division 2; or a Zone 22 location shall be suitable for such location. Such fixtures shall be serviced from outside the spray area. [33:6.6.2]
      3. Luminaires, like that shown in Figure 516.6(C)(b), that are an integral part of the walls or ceiling of a spray area shall be permitted to be separated from the spray area by glass panels that are an integral part of the fixture. Such fixtures shall be listed for use in Class I, Division 2; Class I, Zone 2; Class II, Division 2; or Zone 22 locations, whichever is applicable, and also shall be listed for accu‐ mulations of deposits of combustible residues. Such fixtures shall be permitted to be serviced from inside the spray area. [33:6.6.3]
        imageExterior of Interior ofspray area spray areaGasket
      4. Glass panels used to separate luminaires from the spray area or that are an integral part of the luminaire shall meet the following requirements.
        1. Panels for light fixtures or for observation shall be of heat-treated glass, laminated glass, wired glass, or hammered-wired glass and shall be sealed to confine vapors, mists, residues, dusts, and deposits to the spray area. [33:5.5.1]Exception: Listed spray booth assemblies that have vision panels constructed of other materials shall be permitted.
        2. Panels for light fixtures shall be separated from the fixture to prevent the surface temperature of the panel from exceeding 93°C (200°F). [33:5.5.2]
        3. The panel frame and method of attachment shall be designed to not fail under fire exposure before the vision panel fails. [33:5.5.3]
    4. Portable Equipment. Portable electric luminaires or other utilization equipment shall not be used in a spray area during spray operations.Exception No. 1: Where portable electric luminaires are required for operations in spaces not readily illuminated by fixed lighting within the spraying area, they shall be of the type identified for Class I, Division 1 or Class 1, Zone 1 locations where readily ignitible residues could be present. [33:6.9 Exception]Exception No. 2: Where portable electric drying apparatus is used in spray booths and the following requirements are met:
      1. The apparatus and its electrical connections are not located within the spray enclosure during spray operations.
      2. Electrical equipment within 450 mm (18 in.) of the floor is iden‐ tified for Class I, Division 2 or Class I, Zone 2 locations.imageFixture mounted behindOpening for fixture
        Mounting gasket
        Removable glass panelSpray area,wall or ceiling
      3. All metallic parts of the drying apparatus are electrically bonded and grounded.
        Cover
        Hinged glass panel
      4. Interlocks are provided to prevent the operation of spray equip‐ ment while drying apparatus is within the spray enclosure, to allow for a 3-minute purge of the enclosure before energizing the drying apparatus and to shut off drying apparatus on failure of ventilation system.

      imageLuminaireSealFrameGlass panelRemovable panel
      N FIGURE 516.6(C)(a) Example of a Luminaire that is Mounted Outside of the Spray Area and is Serviced from Outside the Spray Area. [33:Figure 6.6.1]N FIGURE 516.6(C)(b) Example of a Luminaire that is an Integral Part of the Spray Area and is Serviced from Inside the Spray Area. [33:Figure 6.6.3]
    5. Electrostatic Equipment. Electrostatic spraying or detear‐ ing equipment shall be installed and used only as provided in 516.10.Informational Note: For further information, see NFPA 33-2016, Standard for Spray Application Using Flammable or Combustible Mate‐ rials.
    6. Static Electric Discharges. All persons and all electrically conductive objects, including any metal parts of the process equipment or apparatus, containers of material, exhaust ducts, and piping systems that convey flammable or combustible liquids, shall be electrically grounded. [34:6.8.1]
  4. Wiring and Equipment Not Within Classified Locations.
  1. Wiring. All fixed wiring above the Class I and II locations shall be in metal raceways, Type PVC conduit, Type RTRC conduit, or electrical nonmetallic tubing; where cables are used, they shall be Type MI, Type TC, or Type MC cable. Cellu‐ lar metal floor raceways shall only be permitted to supply ceil‐ ing outlets or as extensions to the area below the floor of a Class I or II location. Where cellular metal raceways are used, they shall not have connections leading into or passing through the Class I or II location unless suitable seals are provi‐ ded.
  2. Equipment. Equipment that could produce arcs, sparks, or particles of hot metal, such as lamps and lampholders for fixed lighting, cutouts, switches, receptacles, motors, or other equipment having make-and-break or sliding contacts, where installed above a classified location or above a location where freshly finished goods are handled, shall be of the totally enclosed type or be constructed so as to prevent the escape of sparks or hot metal particles.

516.10 Special Equipment.

  1. Fixed Electrostatic Equipment. This section shall apply to any equipment using electrostatically charged elements for the atomization, charging, and/or precipitation of hazardous materials for coatings on articles or for other similar purposes in which the charging or atomizing device is attached to a mechanical support or manipulator. This shall include robotic devices. This section shall not apply to devices that are held or manipulated by hand. Where robot or programming proce‐ dures involve manual manipulation of the robot arm while spraying with the high voltage on, the provisions of 516.10(B) shall apply. The installation of electrostatic spraying equipment shall comply with 516.10(A)(1) through (A)(10). Spray equip‐ ment shall be listed. All automatic electrostatic equipment systems shall comply with 516.6(A) through (E).
    1. Power and Control Equipment. Transformers, high- voltage supplies, control apparatus, and all other electrical portions of the equipment shall be installed outside of the Class I location or be of a type identified for the location.Exception: High-voltage grids, electrodes, electrostatic atomizing heads, and their connections shall be permitted within the Class I location.
    2. Electrostatic Equipment. Electrodes and electrostatic atomizing heads shall be adequately supported in permanent locations and shall be effectively insulated from ground. Elec‐ trodes and electrostatic atomizing heads that are permanently attached to their bases, supports, reciprocators, or robots shall be deemed to comply with this section.
    3. High-Voltage Leads. High-voltage leads shall be properly insulated and protected from mechanical damage or exposure to destructive chemicals. Any exposed element at high voltage shall be effectively and permanently supported on suitable insulators and shall be effectively guarded against accidental contact or grounding.
    4. Support of Goods. Goods being coated using this process shall be supported on conveyors or hangers. The conveyors or hangers shall be arranged (1) to ensure that the parts being coated are electrically connected to ground with a resistance of 1 megohm or less and (2) to prevent parts from swinging.
    5. Automatic Controls. Electrostatic apparatus shall be equipped with automatic means that will rapidly de-energize the high-voltage elements under any of the following condi‐ tions:
      1. Stoppage of ventilating fans or failure of ventilating equipment from any cause
      2. Stoppage of the conveyor carrying goods through the high-voltage field unless stoppage is required by the spray process
      3. Occurrence of excessive current leakage at any point in the high-voltage system
      4. De-energizing the primary voltage input to the power supply
    6. Grounding. All electrically conductive objects in the spray area, except those objects required by the process to be at high voltage, shall be adequately grounded. This requirement shall apply to paint containers, wash cans, guards, hose connectors, brackets, and any other electrically conductive objects or devi‐ ces in the area.Informational Note: For more information on grounding and bonding for static electricity purposes, see NFPA 33-2016, Stand‐ ard for Spray Application Using Flammable or Combustible Materials; NFPA 34-2015, Standard for Dipping, Coating, and Printing Processes Using Flammable or Combustible Liquids; and NFPA 77-2014, Recom‐ mended Practice on Static Electricity.
    7. Isolation. Safeguards such as adequate booths, fencing, railings, interlocks, or other means shall be placed about the equipment or incorporated therein so that they, either by their location, character, or both, ensure that a safe separation of the process is maintained.
    8. Signs. Signs shall be conspicuously posted to convey the following:
      1. Designate the process zone as dangerous with regard to fire and accident
      2. Identify the grounding requirements for all electrically conductive objects in the spray area
      3. Restrict access to qualified personnel only
      1. Insulators. All insulators shall be kept clean and dry.
      2. Other Than Nonincendive Equipment. Spray equipment that cannot be classified as nonincendive shall comply with 516.10(A)(10)(a) and (A)(10)(b).
        1. Conveyors, hangers, and application equipment shall be arranged so that a minimum separation of at least twice the sparking distance is maintained between the workpiece or material being sprayed and electrodes, electrostatic atomizing heads, or charged conductors. Warnings defining this safe distance shall be posted. [33:11.4.1]
        2. The equipment shall provide an automatic means of rapidly de-energizing the high-voltage elements in the event the distance between the goods being painted and the electro‐ des or electrostatic atomizing heads falls below that specified in 516.10(A)(10)(a). [33:11.3.8]
  2. Hand-Spraying Electrostatic Equipment. This section shall apply to any equipment using electrostatically charged elements for the atomization, charging, or precipitation of flammable and combustible materials for coatings on articles, or for other similar purposes in which the charging or atomiz‐ ing device is hand-held and manipulated during the spraying operation. Electrostatic hand-spraying equipment and devices used in connection with paint-spraying operations shall be of listed types and shall comply with 516.10(B)(1) through (B)(5).
    1. General. The high-voltage circuits shall be designed so as not to produce a spark of sufficient intensity to ignite the most readily ignitible of those vapor–air mixtures likely to be encountered or result in appreciable shock hazard upon coming in contact with a grounded object under all normal operating conditions. The electrostatically charged exposed elements of the handgun shall be capable of being energized only by an actuator that also controls the coating material supply.
    2. Power Equipment. Transformers, power packs, control apparatus, and all other electrical portions of the equipment
      shall be located outside of the Class I location or be identified for the location.Exception: The handgun itself and its connections to the power supply shall be permitted within the Class I location.
    3. Handle. The handle of the spraying gun shall be electri‐ cally connected to ground by a conductive material and be constructed so that the operator in normal operating position is in electrical contact with the grounded handle with a resist‐ ance of not more than 1 megohm to prevent buildup of a static charge on the operator’s body. Signs indicating the necessity for grounding other persons entering the spray area shall be conspicuously posted.
    4. Electrostatic Equipment. All electrically conductive objects in the spraying area, except those objects required by the process to be at high voltage shall be electrically connected to ground with a resistance of not more than 1 megohm. This requirement shall apply to paint containers, wash cans, and any other electrical conductive objects or devices in the area. The equipment shall carry a prominent, permanently installed warning regarding the necessity for this grounding feature.Informational Note: For more information on grounding and bonding for static electricity purposes, see NFPA 33-2016, Stand‐ ard for Spray Application Using Flammable or Combustible Materials; NFPA 34-2015, Standard for Dipping, Coating, and Printing Processes Using Flammable or Combustible Liquids; and NFPA 77-2007, Recom‐ mended Practice on Static Electricity.
    5. Support of Objects. Objects being painted shall be main‐ tained in electrical contact with the conveyor or other groun‐ ded support. Hooks shall be regularly cleaned to ensure adequate grounding of 1 megohm or less. Areas of contact shall be sharp points or knife edges where possible. Points of support of the object shall be concealed from random spray where feasible, and, where the objects being sprayed are supported from a conveyor, the point of attachment to the conveyor shall be located so as to not collect spray material during normal operation.
  3. Powder Coating. This section shall apply to processes in which combustible dry powders are applied. The hazards asso‐ ciated with combustible dusts are present in such a process to a degree, depending on the chemical composition of the mate‐ rial, particle size, shape, and distribution.
    1. Electrical Equipment and Sources of Ignition. Electrical equipment and other sources of ignition shall comply with the requirements of Article 502. Portable electric luminaires and other utilization equipment shall not be used within a Class II location during operation of the finishing processes. Where such luminaires or utilization equipment are used during cleaning or repairing operations, they shall be of a type identi‐ fied for Class II, Division 1 locations, and all exposed metal parts shall be connected to an equipment grounding conduc‐ tor.Exception: Where portable electric luminaires are required for operations in spaces not readily illuminated by fixed lighting within the spraying area, they shall be of the type listed for Class II, Division 1 locations where readily ignitible residues may be present.
    2. Fixed Electrostatic Spraying Equipment. The provisions of 516.10(A) and 516.10(C)(1) shall apply to fixed electrostatic spraying equipment.
    3. Electrostatic Hand-Spraying Equipment. The provisions of 516.10(B) and 516.10(C)(1) shall apply to electrostatic hand- spraying equipment.
    4. Electrostatic Fluidized Beds. Electrostatic fluidized beds and associated equipment shall be of identified types. The high-voltage circuits shall be designed such that any discharge produced when the charging electrodes of the bed are approached or contacted by a grounded object shall not be of sufficient intensity to ignite any powder–air mixture likely to be encountered or to result in an appreciable shock hazard.
      1. Transformers, power packs, control apparatus, and all other electrical portions of the equipment shall be located outside the powder-coating area or shall otherwise comply with the requirements of 516.10(C)(1).Exception: The charging electrodes and their connections to the power supply shall be permitted within the powder-coating area.
      2. All electrically conductive objects within the powder- coating area shall be adequately grounded. The powder- coating equipment shall carry a prominent, permanently installed warning regarding the necessity for grounding these objects.Informational Note: For more information on grounding and bonding for static electricity purposes, see NFPA 33-2016, Stand‐ ard for Spray Application Using Flammable or Combustible Materials; NFPA 34-2015, Standard for Dipping, Coating, and Printing Processes Using Flammable or Combustible Liquids; and NFPA 77-2014, Recom‐ mended Practice on Static Electricity.
      3. Objects being coated shall be maintained in electrical contact (less than 1 megohm) with the conveyor or other support in order to ensure proper grounding. Hangers shall be regularly cleaned to ensure effective electrical contact. Areas of electrical contact shall be sharp points or knife edges where possible.
      4. The electrical equipment and compressed air supplies shall be interlocked with a ventilation system so that the equipment cannot be operated unless the ventilating fans are in operation. [33:Chapter 15]

516.16 Grounding. All metal raceways, the metal armors or metallic sheath on cables, and all non–current-carrying metal parts of fixed or portable electrical equipment, regardless of voltage, shall be grounded and bonded. Grounding and bond‐ ing shall comply with 501.30, 502.30, or 505.25, as applicable.

Part IV. Spray Application Operations in Membrane Enclo‐ sures

516.18 Area Classification for Temporary Membrane Enclo‐ sures. Electrical area classification shall be as follows:

  1. The area within the membrane enclosure shall be consid‐ ered a Class I, Division 1 area, as shown in Figure 516.18.
  2. A 1.5 m (5 ft) zone outside of the membrane enclosure shall be considered Class I, Division 2, as shown in Figure 516.18.

Informational Note No. 1: The risks to people and property are unique when spray painting within the confined spaces of temporary membrane enclosures. See NFPA 33-2016, Standard for Spray Application Using Flammable or Combustible Materials, for information on occupancy, ventilation, fire protection, and permitting for spray application operations in membrane enclo‐ sures. NFPA 33-2016 limits spray application operations within

both outdoor and indoor temporary membrane enclosures, as well as use and time constraints.

Informational Note No. 2: Section 18.6 of NFPA 33-2016, Stand‐ ard for Spray Application Using Flammable or Combustible Materials, limits material used in a vertical plane for membrane enclo‐ sures. See also NFPA 701-2015, Standard Methods of Fire Tests for Flame Propagation of Textiles and Films, Test Method 2 for construc‐ tion information.

Informational Note No. 3: See 18.3.2.1.1 of NFPA 33-2016, Standard for Spray Application Using Flammable or Combustible Mate‐ rials, for membrane installation beneath sprinklers. See also

8.15.15 of NFPA 13-2014, Standard for the Installation of Sprinkler Systems, for protection of membrane structures.

516.23 Electrical and Other Sources of Ignition. Electrical wiring and utilization equipment used within the classified areas inside and outside of membrane enclosures during spray painting shall be suitable for the location and shall comply with all of the following:

  1. All power to the workpiece shall be removed during spray painting.
  2. Workpieces shall be grounded.
  3. Spray paint equipment shall be grounded.
  4. Scaffolding shall be bonded to the workpiece and groun‐ ded by an approved method.

Part V. Printing, Dipping, and Coating Processes

516.29 Classification of Locations. Classification is based on quantities of flammable vapors, combustible mists, residues, dusts, or deposits that are present or might be present in quan‐ tities sufficient to produce ignitable or explosive mixtures with air. Electrical wiring and electrical utilization equipment loca‐ ted adjacent to open processes shall comply with the require‐ ments as follows. Examples of these requirements are illustrated in Figure 516.29(a), Figure 516.29(b), Figure 516.29(c), and Figure 516.29(d).

Informational Note: For additional guidance, see Chapter 6 of NFPA 33-2016, Standard for Spray Application Using Flammable or Combustible Materials, and Chapter 6 of NFPA 34-2015, Standard for Dipping, Coating, and Printing Processes Using Flammable or Combustible Liquids.

image

Extent of the Class I, Division 2

1525 mm (5 ft)

Class I, Division 1

1525 mm              

(5 ft)

Membrane enclosure

shown)

(support structure not

Workpiece

image

Extent of the Class I, Division 2

Membrane enclosure (support structure not shown)

1525 mm (5 ft)

1525 mm (5 ft)

Workpiece

Class I, Division 1, within the membrane enclosure

PLAN VIEW

ELEVATION

FIGURE 516.18 Electrical Classifications for Temporary Outdoor Membrane Enclosures [33:Figure 18.7.1.1]

  1. Electrical wiring and electrical utilization equipment loca‐ ted in any sump, pit, or below grade channel that is within 7620 mm (25 ft) horizontally of a vapor source, as defined by this standard, shall be suitable for Class I, Divi‐ sion 1 or Class I, Zone 1 locations. If the sump, pit, or channel extends beyond 7620 mm (25 ft) of the vapor source, it shall be provided with a vapor stop, or it shall be classified as Class I, Division 1 or Class I, Zone 1 for its entire length. [34:6.4.1]
  2. Electrical wiring and electrical utilization equipment loca‐ ted within 1525 mm (5 ft) of a vapor source shall be suita‐ ble for Class I, Division 1 or Class I, Zone 1 locations. The space inside a dip tank, ink fountain, ink reservoir, or ink tank shall be classified as Class I, Division 1 or Class I, Zone 0, whichever is applicable.
  3. Electrical wiring and electrical utilization equipment loca‐ ted within 915 mm (3 ft) of the Class I, Division 1 or Class I, Zone 1 location shall be suitable for Class I, Divi‐ sion 2 or Class I, Zone 2 locations, whichever is applica‐ ble.
  4. The space 915 mm (3 ft) above the floor and extending 6100 mm (20 ft) horizontally in all directions from the Class I, Division 1 or Class I, Zone 1 location shall be clas‐ sified as Class I, Division 2 or Class I, Zone 2, and electri‐ cal wiring and electrical utilization equipment located within this space shall be suitable for Class I, Division 2 or Class I, Zone 2 locations, whichever is applicable.
  5. This space shall be permitted to be nonclassified for purposes of electrical installations if the surface area of the vapor source does not exceed 0.5 m2 (5 ft2), the contents of the dip tank, ink fountain, ink reservoir, or ink tank do not exceed 19 L (5 gal), and the vapor concentration during operating and shutdown periods does not exceed 25 percent of the lower flammable limit.
image

Peripheral vapor

ventilation

915 mm

Saturated      (3 ft) vapor blanket

915 mm

(3 ft)

Exhaust

plenum

Vapor-

condensing coils

Ventilation inlet at floor level

Pit

Spill containment

Liquid

image Class I, Division 1 or Zone 0 image Class I, Division 1 or Zone 1 image Class I, Division 2 or Zone 2

Definitions

Freeboard: The distance from the maximum solvent or coating material level to the top of the tank

Freeboard ratio: The freeboard height divided by the smaller of the interior length or interior width of the tank

N FIGURE 516.29(b) Electrical Area Classification for Open Dipping and Coating Processes with Peripheral Vapor Containment and Ventilation — Vapors Confined to Process Equipment. [34:Figure 6.4(b)]

image

1525 mm

(5 ft)

1525 mm

(5 ft)

Point beyond which object is

no longer a vapor source

Conveyor rail

915 mm

(3 ft)

915 mm

(3 ft)

915 mm

(3 ft)

1525 mm

(5 ft)

915 mm

(3 ft)

Diptank

Pit

915 mm      

(3 ft)

Floor

Drainboard

915 mm (3 ft)

6100 mm (20 ft)

1525 mm

(5 ft)

1525 mm 1525 mm

(5 ft) (5 ft)          6100 mm (20 ft)

image

Class I, Division 1 or Zone 0 Class I, Division 1 or Zone 1 Class I, Division 2 or Zone 2

N FIGURE 516.29(a) Electrical Area Classification for Open Dipping and Coating Processes Without Vapor Containment or Ventilation. [34:Figure 6.4(a)]

image

460 mm

(1.5 ft)

610 mm (2 ft)

915 mm (3 ft)

Pit

Exhaust duct

Liquid

  1. The space within 915 mm (3 ft) in all directions from any opening in the enclosure and extending to the floor or grade level shall be classified as Class I, Division 2 or Class I, Zone 2, and electrical wiring and electrical utiliza‐ tion equipment located within this space shall be suitable for Class I, Division 2 locations or Class I, Zone 2 loca‐ tions, whichever is applicable.
  2. All other spaces adjacent to an enclosed dipping or coat‐ ing process or apparatus shall be classified as nonhazar‐ dous for purposes of electrical installations.
  1. Equipment and Containers in Ventilated Areas. Open containers, supply containers, waste containers, and solvent distillation units that contain Class I liquids shall be located in       3050 mm       (10 ft)
    image Class I, Division 1 or Zone 0 image Class I, Division 1 or Zone 1 image Class I, Division 2 or Zone 2
    N FIGURE 516.29(c) Electrical Area Classification for Open Dipping and Coating Processes with Partial Peripheral Vapor Containment and Ventilation — Vapors NOT Confined to Process Equipment. [34:Figure 6.4(c)]
    image1525 mm(5 ft)
    915 mm(3 ft)areas ventilated in accordance with 516.4.
  2. Luminaires. For printing, coating, and dipping equip‐ ment where the process area is enclosed by glass panels that are sealed to confine vapors and mists to the inside of the enclo‐ sure, luminaires that are attached to the walls or ceilings of a process enclosure and that are located outside of any classified area shall be permitted to be of general purpose construction. Such luminaires shall be serviced from outside the enclosure.Luminaires that are attached to the walls or ceilings of a process enclosure, are located within the Class I, Division 2 or Class I, Zone 2 location, and are separated from the process area by glass panels that are sealed to confine vapors and mists shall be suitable for use in that location. Such fixtures shall be serviced from outside the enclosure.
  3. Wiring and Equipment Not Within Classified Locations.
  1. Wiring. All fixed wiring above the Class I and II locations shall be in metal raceways, Type PVC conduit, Type RTRC conduit, or electrical nonmetallic tubing; where cables are used, they shall be Type MI, Type TC, or Type MC cable. Cellu‐ lar metal floor raceways shall only be permitted to supply ceil‐ ing outlets or as extensions to the area below the floor of a Class I or II location. Where cellular metal raceways are used, they shall not have connections leading into or passing through the Class I or II location unless suitable seals are provi‐6100 mm(20 ft)image Class I, Division 1 or Zone 0 image Class I, Division 1 or Zone 1 image Class I, Division 2 or Zone 21525 mm(5 ft)915 mm(3 ft)ded.
  2. Equipment. Equipment that is capable of producing arcs, sparks, or particles of hot metal, such as lamps and lamphold‐ ers for fixed lighting, cutouts, switches, receptacles, motors, or other equipment having make-and-break or sliding contacts, where installed above a classified location or above a location where freshly finished goods are handled, shall be of the totally

N FIGURE 516.29(d) Electrical Area Classification for a Typical Printing Process. [34:Figure 6.4(d)]

516.35 Areas Adjacent to Enclosed Dipping and Coating Processes. Areas adjacent to enclosed dipping and coating processes are illustrated by Figure 516.35 and shall be classified as follows:

(1) The interior of any enclosed dipping or coating process or apparatus shall be a Class I, Division 1 or Class I, Zone 1 location, and electrical wiring and electrical utilization equipment located within this space shall be suitable for Class I, Division 1 or Class I, Zone 1 locations, whichever is applicable. The area inside the dip tank shall be classi‐ fied as Class I, Division 1 or Class I, Zone 0, whichever is applicable.

enclosed type or be constructed so as to prevent the escape of sparks or hot metal particles.

516.40 Static Electric Discharges. All persons and all electri‐ cally conductive objects, including any metal parts of the proc‐ ess equipment or apparatus, containers of material, exhaust ducts, and piping systems that convey flammable or combusti‐ ble liquids, shall be electrically grounded.

Provision shall be made to dissipate static electric charges from all nonconductive substrates in printing processes.

Informational Note: For additional guidance on reducing the risk of ignition from electrostatic discharges, see NFPA 77-2014, Recommended Practice on Static Electricity.

Conveyor rail

915 mm

(3 ft)

           Vestibule

Enclosed vapor/drain tunnel

Vapor confined to enclosed tunnel

Oven

Drainboard Vapor space

915 mm

(3 ft)

Classification of interior

of oven governed by NFPA 86

915 mm

(3 ft)

915 mm

(3 ft)

Class I, Division 1 or Zone 0 Class I, Division 1 or Zone 1 Class I, Division 2 or Zone 2

image
image
image

N FIGURE 516.35 Electrical Area Classification Around Enclosed Dipping and Coating Processes. [34:Figure 6.5]

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