The application of spray undercoating or body lining in vehicles generates flammable aerosols and vapors. To mitigate the risk of ignition, a minimum separation distance from potential ignition sources is required. NFPA 30A, Code for Motor Fuel Dispensing Facilities and Repair Garages, explicitly mandates that these operations must be conducted in an area located at least 20 ft (6.1 m) from open flames and any equipment that can produce sparks. This distance provides a buffer zone, allowing flammable vapors to disperse and their concentration to fall below the lower flammable limit before reaching an ignition source.

A. 3 ft (914 mm) is an insufficient distance to prevent the ignition of flammable vapors, which can easily travel this far in a flammable concentration.

B. 5 ft (1,524 mm) does not provide an adequate safety margin for the flammable atmosphere created during spraying operations as required by the code.

C. 10 ft (3,048 mm) is less than the minimum distance specified by the relevant NFPA code for this specific hazardous operation.

1. National Fire Protection Association (NFPA). (2021). NFPA 30A: Code for Motor Fuel Dispensing Facilities and Repair Garages. Section 7.6.6.2. "Spray undercoating or spray body lining of vehicles shall be conducted in an area that is located a minimum of 20 ft (6.1 m) from open flames and spark-producing equipment."

2. National Fire Protection Association (NFPA). (2021). Fire Protection Handbook (21st ed.). Volume 2, Section 16, Chapter 10, "Motor Fuel Dispensing and Repair Facilities," p. 16-219. The handbook discusses the hazards in repair garages and references the requirements of NFPA 30A, including separation distances for hazardous operations like undercoating.