The 2016 edition of NFPA 110 – Standard for Emergency and Standby Power System states that:

“Section 7.9.13. Automatically actuated valves shall not be permitted in the fuel oil supply or fuel oil return lines.”

The intent is to avoid inadvertent interruption of the fuel supply by unintended or improper operation of a valve or its controls. Automatic control of fuel valves adds a layer of complexity to the fuel system and creates a single point of failure for the emergency power supply (EPS). There is no corresponding prohibition of manually operated valves. These valves are typically used to isolate portions of the fuel, allowing for continued operation of the system when one of its components requires maintenance. Section 7.9.11, unchanged from the previous edition, requires that manual valves provide a visual indication of their status. There is no direct requirement that manual valves be supervised to ensure that they are left in the open position after maintenance activities.

“Section 7.9.11. All manual fuel system valves shall be of the indicating type.”