Main Tank: A separate, main fuel tank for supplying fuel to the engine or a day tank.
Day Tank: A fuel tank, located inside a structure that provides fuel to the engine.
Integral Tank: A fuel tank furnished by the generator manufacturer and mounted on the engine.
Base Tank: A fuel tank furnished by the generator manufacturer and mounted under the engine as a base.

Why use a Day Tank between the Main Tank and the generator?

Paragraphs 7.9.2 and 7.9.2.1 of NFPA 110 states that:

7.9.2. Fuel tanks shall be close enough to the prime mover (engine) for the fuel lift (suction head) of the
prime mover fuel pump to meet the fuel system requirements, or a fuel transfer pump and day tank shall
be provided.

7.9.2.1. If the engine manufacturer’s fuel pump static head pressure limits are exceeded when the level
of fuel in the tank is at maximum, a day tank shall be utilized.

Based on NFPA 110 – Standard for Emergency and Standby Power Systems, 2016 Edition
National Fire Protection Association

Created by: Eric A. Arevalo
Uncontrolled once printed