In situations wherein commodities of a dangerous nature must be unloaded or rearranged from overloaded vehicles, every precaution applicable in such situation must be exercised to insure the safety of the public. In every event, the owner, driver, or person who has physical control of the truck or cargo should be allowed ample time to acquire safe and proper equipment for unloading or handling. In no event shall members of the department knowingly permit dangerous or inflammable materials to be discharged in such manner as to constitute a hazard.