Korea Ever-Power · YB2 Series · Spray Booth and Coating Line Drive Guide

During active spray operations, the interior of the spray booth is Zone 1: an explosive solvent vapour-air mixture is likely to be present during normal spraying. The spray zone extends from the floor to the ceiling and the full width and depth of the booth interior. All electrical equipment within the booth boundary — including the exhaust fan motor, any conveyor drive inside the booth, and any lighting — must be ATEX/IECEx certified for Zone 1 service.

The area immediately outside the spray booth opening (within 1 m of the booth face opening), the area around any spray booth ventilation supply or exhaust duct openings (within 1 m), and the area around paint mixing rooms (within 1 m of any open container) are classified as Zone 2. Motors in Zone 2 must be certified Ex d or equivalent for Zone 2 service. A Zone 1 certified YB2 motor is also suitable for Zone 2 installation.

If the exhaust fan is located on the roof of the building or in an external plenum more than 3 m from the spray booth exhaust duct opening, it may fall outside the classified zone boundary. However, the exhaust airstream itself may contain solvent vapour above the lower explosive limit (LEL) if the booth ventilation rate is insufficient, making the fan impeller and motor a potential ignition source. Korea Ever-Power recommends always specifying YB2 Ex d for both exhaust and supply fan motors on spray booth ventilation systems regardless of fan location relative to zone boundaries.

Spray booth exhaust fan power depends on the booth face area, face velocity, duct static pressure loss, and fan efficiency. For a typical automotive spray booth 4 m wide × 2.5 m high at 0.5 m/s face velocity: Q = 4.0 × 2.5 × 0.5 = 5.0 m³/s. At 200 Pa duct static pressure and 65% fan efficiency: motor power = 5.0 × 200 ÷ (1,000 × 0.65) = 1.54 kW. With service factor 1.25: select YB2 2.2 kW, 4-pole or 2-pole, Ex d IIB T4.

The fan motor may be belt-driven from outside the Zone 1 boundary through a shaft penetration in the booth wall, with only the impeller inside the booth. In this case, the motor shaft seal and the motor itself may be in Zone 2 rather than Zone 1. However, Korea Ever-Power recommends YB2 Ex d IIB T4 for both Zone 1 and Zone 2 positions on spray booth fans — the motor is directly connected to the fan impeller that handles explosive atmosphere, and any motor fault that generates heat must be contained within the Zone 1/2 motor specification. Do not use standard motors even if the motor body is claimed to be outside the classified zone.

Every spray booth must have an airflow interlock that inhibits spray gun operation if the exhaust fan motor is not running or if the measured face velocity falls below the minimum safe level. This interlock is typically achieved with an airflow switch or differential pressure sensor in the exhaust duct, connected through a safety relay to the spray gun supply circuit. The YB2 exhaust fan motor must start and prove airflow before the spray interlock permits the spray gun to operate.

Overhead chain conveyors passing through spray booths use drive motors located outside the spray zone where possible, with the conveyor chain entering and exiting the booth through small openings. When the conveyor drive motor must be located inside the spray zone (for compact booth layouts), specify YB2 0.55 to 3.0 kW Ex d IIB T4 for the drive head. The motor must also be rated for continuous S1 duty at the conveyor line speed without overloading, as any motor overload in an explosive atmosphere creates a T4 surface temperature exceedance risk.

Floor-level slat conveyors or roller conveyors carrying work pieces through a horizontal spray booth have motors in the spray zone floor area. Solvents are heavier than air and tend to accumulate at floor level — the floor area inside a spray booth may have higher solvent concentrations than the mid-zone where the spray plume is. All floor-level conveyor motors inside the booth must be YB2 Ex d IIB T4. IP55 provides protection against paint overspray landing on the motor during spraying.

The Korea Ever-Power YB2 Ex d IIB T4 is the complete motor specification for all Zone 1 and Zone 2 motors in paint spray booths, coating lines, and paint mixing rooms. It provides ATEX and IECEx certification, IP55 protection against paint overspray and water washdown, T4 surface temperature limit for all common paint solvents, and the same IEC metric frame dimensions as the standard Y2 for easy retrofit into existing spray booth installations. The complete YB2 range is available in the explosion-proof motor product section. For spray booth installations requiring VFD speed control of exhaust fans for variable airflow, contact Korea Ever-Power for Ex d motor VFD compatibility guidance.

Furniture and wood product spray lines using nitrocellulose lacquers and polyurethane finishes. Exhaust fans YB2 1.5 to 11 kW. Nitrocellulose lacquers use ethyl acetate and butyl acetate — Group IIA; YB2 IIB covers both. High paint spray volumes in wood coating lines require very high air change rates and correspondingly powerful exhaust fans.

Paint mixing and thinning rooms where solvent containers are opened and paint is thinned to spray viscosity. Zone 2 in general mixing room area. Exhaust fan: YB2 0.55 to 2.2 kW to maintain 6 to 10 air changes per hour. Any electrical equipment in the mixing room including the exhaust fan motor must be Zone 2 certified.

Solvent recovery and recirculation systems on large coating lines recover solvent from exhaust air for reuse. The recovery unit fan and any pump motors handling solvent-laden air or liquid solvent are in Zone 1 or Zone 2 depending on their position relative to the recovery vessel. YB2 0.75 to 5.5 kW for recovery unit fan and pump drives.

Flash-off oven exhaust fans handling high concentrations of solvent vapour evaporating from wet paint film immediately after spraying. Zone 1 classification applies to the flash-off zone exhaust duct interior. YB2 2.2 to 11 kW, 2-pole for high-airflow flash-off exhaust at elevated temperature (ambient up to 60°C — specify derated motor power for elevated ambient).