An industrial oven that drives solvent out of a coating is, functionally, a heated vessel that manufactures flammable vapor and then holds it at elevated temperature. Every hour of operation liberates solvent from the product into a confined space that already has an ignition source in the form of burners or heating elements. The hazard is not that the oven might catch fire. It is that the atmosphere inside the oven can reach an explosive concentration.
NFPA 86 addresses this primarily through prevention rather than suppression. Safety ventilation dilutes the atmosphere to keep it below a fraction of the lower explosive limit. The purge cycle clears any accumulated vapor before an ignition source is introduced at startup. Explosion relief provides a designed failure path if the atmosphere does ignite. Suppression is a layer on top of that structure, not a substitute for any part of it.
The failure mode that produces most oven incidents is a defeated or degraded safety interlock. A purge timer bypassed to shorten cycle time, an airflow switch jumpered because it was nuisance-tripping, a ventilation fan that has lost capacity through a fouled duct. Each of these removes a layer that was doing real work, and none of them announce themselves until the oven lights off into an atmosphere it should never have been allowed to ignite.