VOCs from coating operations pose environmental and regulatory challenges. The EPA 5-Point Permanent Total Enclosure (PTE) Criteria provides guidelines to capture VOCs effectively and direct them to control devices, ensuring compliance, safety, and operational efficiency.

1. Importance of PTE Criteria

PTE criteria define how VOC sources should be enclosed to prevent uncontrolled emissions. This applies to spray booths, ovens, coater hoods, and similar operations. Proper implementation ensures emissions are captured and treated by control devices, such as oxidizers or VOC concentrators.

2. Key Definitions

Natural Draft Openings (NDO): Openings that remain open during operation for air intake.

Permanent Total Enclosure (PTE): Fully enclosed structure around a VOC source—including walls, ceiling, floor, and doors—directing all emissions to a control device.

Face Velocity (FV): Measured air movement through an opening (ft/min). Average FV must be ≥200 FPM, flowing into the PTE.

3. Core Compliance Requirements

NDO Placement: ≥4 equivalent diameters from VOC sources.

NDO Surface Area: ≤5% of total PTE area (walls, ceiling, floor).

Face Velocity: ≥200 FPM directed inward.

Access Controls: All non-NDO doors/windows must remain closed; self-closing preferred.

Exhaust Routing: All PTE emissions must go to a control device.

4. Natural Draft Openings (NDOs)

Area Inclusions: Walls, floors, ceilings, doors, windows.

Operational Guidelines: Material entrances must be closed after use; personnel doors should be self-closing. Oven walls, floors, and ceilings in the heating zone are included in the PTE.

5. Airflow and Face Velocity

Minimum FV: 200 FPM (~2.3 MPH).

Flow Direction: Air must move into the enclosure. Nearby openings or blowers must not disrupt airflow.

Structural Adjustments: Seal or remove doors/windows that compromise inward flow.

6. Non-NDO Openings

Roll Coater Doors: Open only for material transfer.

Roof Panels: Remove only for maintenance.

HVAC Inlets: Count as NDOs for airflow purposes.

7. Exhaust and Control Devices

All PTE exhaust must connect to an approved device.

Ovens and Coater Hoods: Typically vent to oxidizers.

VOC Concentrators: Capture emissions before final destruction in the oxidizer.

8. Conclusion

EPA 5-Point PTE compliance ensures VOCs are captured, directed, and destroyed efficiently. Key takeaways:

Proper enclosure design (walls, floors, ceilings, doors).

Correct sizing and placement of NDOs.

Maintain minimum inward face velocity.

Exhaust VOCs through a control device.

At Ship & Shore Environmental, Inc., we specialize in designing and optimizing VOC control systems that integrate with your operations. Our solutions ensure regulatory compliance, operational efficiency, and safer, cleaner industrial processes.

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