Two routes to explosion control
| NFPA 68 — deflagration venting | NFPA 69 — explosion prevention | |
|---|---|---|
| Principle | Let a deflagration happen, but relieve the pressure through vent panels so the enclosure does not rupture | Stop a flammable mixture forming, typically by exhaust ventilation |
| Design target | Reduced pressure below enclosure strength; safe vent direction | Gas concentration below 25 % LFL |
| Key inputs | Burning velocity, Pmax, enclosure volume, vent opening pressure | Gas generation rate and composition, airflow |
| Verification | Calculation, CFD simulation, deflagration test | Calculation, CFD simulation; detection and controls |
What we do
- Data: UL 9540A cell tests give the gas composition, LFL, burning velocity and Pmax that both standards need.
- Design analysis: vent area calculation to NFPA 68 and dispersion analysis to NFPA 69, including single-failure cases of the ventilation system.
- Simulation: 1:1 CFD models of the container that track gas dispersion, overpressure and flame — and test whether added protection works.
- Testing: container-scale deflagration tests at our Nantong site to verify the design.
Frequently asked questions
Which inputs does an NFPA 68 vent calculation need?
The gas composition and its burning velocity and maximum explosion pressure (from the UL 9540A cell test), the enclosure volume and geometry, the vent panel's opening pressure and the strength of the enclosure.
Is NFPA 69 ventilation enough on its own?
NFPA 69 ventilation must keep the flammable gas concentration below 25 % of the LFL for the expected gas release. NFPA 855 also expects the design to consider failures; many designs combine ventilation with deflagration venting.