6. Gravity distribution systems are prohibited, unless specifically approved by the Chief.
7. When such lines lead into buildings, anti- siphon valves shall be installed at the highest point in the supply line where it leaves the top of the tank. Approved substitute protection may be provided for highly volatile liquids.
8. Where necessary for public safety, valves shall be provided to permit proper emergency control for piping systems at each independent element of use therein. The Chief may require piping systems to be equipped with block valves at such locations as may be deemed essential for public safety.