What is the regulated volume at which the handling or use of compressed flammable gas requires a permit?

The correct answer is based on the regulatory standards that dictate when a permit is needed for the handling or use of compressed flammable gas. The regulated volume requiring a permit is set at 400 SCF (standard cubic feet). This threshold is established to ensure safety in the storage and usage of flammable gases, as larger quantities increase the risk of fire and explosion.

Regulatory bodies have determined that at this specific volume, additional precautions and oversight are warranted to protect both individuals and property. The regulations help ensure that proper safety measures are in place for handling significant quantities of potentially hazardous materials.