It shall be unlawful for any person to place or cause to be placed upon or about any fire hydrant any rubbish, building material, fence or other obstruction of any character, or in any manner obstruct, hinder or delay the Fire Department in the performance of its duties in case of fire. Nor shall any person fasten to any fire hydrant any guy rope or brace, nor stand any vehicle within 15 feet of any such hydrant.