Earthsafe MM550 Fuel Refill System for Generators

M50 Auto-Refill Unit for Sub-Base Fuel Tanks

Sub-Base (Belly) Tank  Refill

The M50 refills Generator Sub-Base (Belly) tanks from a remote fuel storage tank.   The unit has onboard controls and transfer pumps with level sensors to mount in the generator sub-base tank.  Controls interface with generator systems with High, Low, Leak Contacts or optional Modbus / BACnet connectivity.  The compact assembly is designed with minimum footprint for installation within generator enclosures, or rooms.

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  • Approvals: UL 508 Controller
  • Power 120-230 VAC, 1 Phase, 50-60 Hz
  • Controller: UL 508, PLC Basis with HMI
  • Interface: Output Relays for High, Low, Leak and Modbus (Optional BACnet)


  • Inlet Solenoid Valves with Strainer and Ball Valve
  • 4 or 5 Point Level Sensor and Leak Sensor
  • Optional Level and Temperature Transmitters
  • Return Flow Pump for Overfill Protection

Safe Fuel Storage Inside Buildings:

Earthsafe day tanks safely store fuel for generator engine consumption within the building. Day tanks are designed with integral secondary containment. Fuel transfer equipment and controls are designed for safe and reliable re-filling.   

Reliable Refill Systems: 

Day Tanks are designed and furnished with pre-assembled and tested fuel transfer equipment and controls. Inlet control valves, transfer pumps, level sensors, leak sensors, and other equipment are all monitored and controlled by the Earthsafe C1 or C8 control panels.

Integrated Building Management Systems:

Earthsafe advanced controllers allow for the communication of vital day tank operating information to other building systems. These systems may include Building Automation Systems, generator controls, switchgear and other power controls, security and fire alarm systems.

Readily Adaptable for Special Operation: 

Earthsafe day tanks can be readily adapated for special operation characteristics such as: dual inlet valves, monitored valve positions, high level / overflow pumping, emergency evacuation, auto-commissioning, fluid metering, high temperature control.