Air pollution control device (APCD) means any equipment that reduces the quantity of a pollutant that is emitted to the air. Examples of APCD currently used on glaze spray booths include, but are not limited to, wet scrubbers, fabric filters, water curtains, and water-wash systems.

Atomization means the conversion of a liquid into a spray or mist (i.e., collection of drops), often by passing the liquid through a nozzle.

Clay ceramics manufacturing facility means a plant site that manufactures pressed tile, sanitaryware, dinnerware, or pottery. For the purposes of this area source rule, the following types of facilities are not part of the regulated category: artisan potters, art studios, school and university ceramic arts programs, and any facility that uses less than 45 Mg/yr (50 tpy) of wet clay.

Clay ceramics metal HAP means an oxide or other compound of chromium, lead, manganese, or nickel, which were listed for Clay Ceramics Manufacturing in the Revised Area Source Category List (67 FR 70428, November 22, 2002).

Glaze means a coating of colored, opaque, or transparent material applied to ceramic products before firing.

Glaze spray booth means a type of equipment used for spraying glaze on ceramic products.

High-volume, low-pressure (HVLP) spray equipment means a type of air atomized spray equipment that operates at low atomizing air pressure (0.1 to 10 pounds per square inch (psi) at the air nozzle) and uses 15 to 30 cubic feet per minute (cfm) of air to minimize the amount of overspray and bounce back.

Kiln means equipment used for the initial curing or firing of glaze on ceramic ware. A kiln may operate continuously or by batch process.

Nonatomizing glaze application technique means the application of glaze in the form of a liquid stream without atomization. Such techniques include, but are not limited to, dipping, centrifugal disc, waterfall, flow coaters, curtain coaters, silk-screening, and any direct application by roller, brush, pad, or other means facilitating direct transfer of glaze.

Plant site means all contiguous or adjoining property that is under common control, including properties that are separated only by a road or other public right-of-way. Common control includes properties that are owned, leased, or operated by the same entity, parent entity, subsidiary, or any combination thereof.

Waste minimization practices mean those procedures employed to minimize material losses and prevent unnecessary waste generation, for example, minimizing glaze overspray emissions using HVLP spray equipment (defined in this section) or similar spray equipment; minimizing HAP emissions during cleanup of spray glazing equipment; operating and maintaining spray glazing equipment according to manufacturer's instructions; and minimizing spills through careful handling of HAP-containing glaze materials.

Water curtain means an APCD that draws the exhaust stream through a continuous curtain of moving water to remove suspended particulate. A water curtain may also be called a drip curtain or waterfall.

Water-wash system means an APCD that uses a series of baffles to redirect the upward exhaust stream through a water wash chamber with downward water flow to remove suspended particulate.