Small and medium commercial facilities need several hours of routine standby
Utility supply is relatively stable and outages are predictable, while the project wants to avoid a separate day tank, transfer pump and complex fuel pipework.
Product Range / Fuel Tank Integrated into the Generator Base
Sub-Base Fuel Tank Diesel Generator Sets
Day-fuel storage is built into the steel generator base, reducing the need for a separate day tank, transfer pump and some external pipework. It suits commercial standby projects with limited space and a defined autonomy target. Open or acoustic enclosures can use the same concept, but usable fuel, filling, venting, draining, spill control and fire-safety boundaries must still be confirmed for the site.
Integrated Sub-BaseTarget RuntimeLess External PipeworkOpen or Acoustic
Why Choose a Sub-Base Fuel Tank
Where space is tight and outage duration is reasonably predictable, an integrated base simplifies day-tank and pipework—but it is not a long-term fuel system
The customer value is a simpler layout and delivery for short-duration standby duty, not unlimited autonomy. A larger base changes overall height, weight, transport, service access and fire conditions, so selection must begin with target hours and usable fuel.
Retrofit buildings or service areas have limited available space
Fuel storage remains within the generator footprint, while adequate space is still reserved for filling, observation, draining and maintenance.
Long continuous runtime is required or local refueling is difficult
Sub-base capacity may not meet the autonomy target. External storage, a day tank, automatic transfer and a safe delivery route may be necessary.
Fuel and fire-management requirements have not been reviewed
Integrating tank and generator does not remove requirements for ventilation, spill containment, separation, refueling procedures or local storage rules.
From Runtime Target to Tank Capacity
Calculate with expected-load fuel consumption, usable volume and reserve—not nominal volume divided by full-load consumption
Actual autonomy changes with load factor, environment, fuel temperature, engine return flow, unusable reserve and tank geometry. Distinguish nominal volume, maximum fill, usable fuel and the low-level alarm point.
Define the hours that must be self-supported
Convert expected outages, refueling response, night or holiday restrictions and critical-load duty into an autonomy target.
Estimate consumption at realistic load factors
Use manufacturer data across several load points rather than one full-load or no-load value for the entire operating period.
Subtract expansion, sediment and unusable pickup volume
The tank cannot be filled to geometric volume; fuel below the pickup, sediment space and thermal expansion allowance are not dependable usable capacity.
Set low-level warning and shutdown boundaries
The warning point must leave enough time for refueling; very-low-level protection should prevent the fuel system from drawing air.
Confirm vehicle access, hose, fill point and working hours
The delivery route must remain accessible during an outage and avoid occupied areas, fire exits, electrical equipment and hot exhaust zones.
Connect external fuel when the sub-base is not enough
Add main storage, day tank, transfer pumps, filtration, valves, leak monitoring and automatic controls as the project requires.
Generator and Fuel Configurations
Combine the sub-base with open, sound-attenuated or external-storage systems according to autonomy and site-management capability
The same engine rating can use different base heights and fuel capacities. Selection also considers operating weight, transport and lifting, vibration isolation, service routes, level visibility and local fire rules.
Integrated Day Tank in a Plant Room
Direct service access and a compact arrangement, with the plant room providing ventilation, exhaust, acoustics, fire protection, foundation and fuel-operation controls.
Outdoor Protection and Routine Autonomy Combined
Generator and fuel storage share an enclosure, requiring review of acoustics, airflow, fill point, service doors and spill containment.
Increase Fuel Capacity without More Footprint
Can extend autonomy but also increases height, weight and center of gravity, so transport, lifting, service access and structural strength must be rechecked.
Use the Sub-Base as a Day Tank in a Long-Duration Fuel System
Add main storage, transfer pumps and control logic while retaining the sub-base as a local buffer and engine supply tank.
A sub-base tank is a configurable part of the generator set, not a standalone fixed model. It can be paired with different engine and alternator brands, ratings, 50Hz/60Hz, voltages and open or acoustic structures; final volume and dimensions follow the project design.
Autonomy and System Boundaries
Separate short self-support, refueling response, long-duration operation and fuel quality before deciding whether a sub-base tank is enough
A sub-base tank provides day-fuel storage close to the engine. Long-duration capability still depends on upstream storage, delivery, filtration, transfer controls, fuel rotation and local supply.
Short-Duration StandbyUsable sub-base fuel directly covers the target hours without immediate refueling
Refuel-to-RunThe sub-base provides a buffer while a delivery vehicle or manual refill arrives before the alarm reserve is consumed
Long Continuous OperationAdd main storage, pumps, a day tank or automatic fuel transfer with appropriate redundancy
Multi-Set SystemUse shared storage and branch supply while coordinating level, return flow and refueling priority for each set
Nominal VolumeGeometric tank volume, not the amount that can be filled or used in service
Usable FuelCapacity available for runtime after expansion, sediment, pickup and safety allowances
Supply and ReturnLine size, pressure differential, return temperature and connection location must suit the engine
Level MonitoringMechanical gauge, sensors, low-level alarm and remote monitoring configured around project risk
Venting and Overfill ControlAllows safe breathing during filling and temperature changes while limiting pressure, vacuum and spills
Draining and CleaningSediment zone, drain and inspection access support removal of water, contamination and aged fuel
Spill ContainmentBunding, double-wall or collection measures and leak checks configured to project requirements
Fuel ManagementSampling, filtration, rotation and records reduce contamination and degradation during long storage
Eight Sub-Base Tank Checkpoints
Customers need not learn tank fabrication, but they should be able to verify capacity, interfaces, welding, leak control and day-to-day usability
Quality means more than a tank hidden in the base. Plate, welds, reinforcement, filling, supply and return, venting, draining, level, containment and service access all affect long-term reliability.
Plate and Reinforcement
Verify material thickness, internal reinforcement, full-fuel weight and base load capacity to limit long-term deformation and vibration cracking.
Continuous Welds and Corrosion Protection
Tank welds should pass leak checks, with interior and exterior surfaces protected for fuel and environmental conditions.
Fill Point and Overfill Control
The fill location should be safe and accessible, with sealing, locking, filtration and overfill measures as required.
Supply and Return Connections
Connection size, location and pipework must match the engine fuel system and avoid air ingress, high resistance or abnormal return flow.
Vent Connection
Maintains pressure balance during filling, consumption and temperature changes, with the outlet protected from weather and contamination.
Level and Alarms
Operators should see available fuel clearly, with low/high-level and remote monitoring available for critical projects.
Drain and Cleaning Access
The sediment zone and drain should allow safe water removal, sampling and cleaning without being blocked by equipment or foundation.
Leak Checks and Service Space
Provide access to pipework, valves, level devices and welds, with collection or containment measures to suit the project.
Six Project Inputs
Tank capacity only becomes meaningful when rating, target hours, refueling, installation, regulations and long-duration plans are clear
Rating basis and expected load factor
Provide prime/standby rating, 50Hz or 60Hz, voltage and main loads so consumption can be estimated across realistic conditions.
Hours that must be supported without refueling
State expected outage duration, delivery response, night or holiday restrictions and required safety reserve.
Vehicle, manual or automatic delivery route
Confirm fuel source, vehicle access, hose distance, fill-point height, responsible crew and outage-time accessibility.
Open, acoustic, plant-room or outdoor installation
Provide available height and footprint, foundation, transport and lifting, service paths, acoustics, airflow and exhaust conditions.
Local fuel-storage, fire and environmental requirements
Confirm permitted storage, spill containment, venting, separation, grounding and refueling controls.
External storage, monitoring and long-duration plan
State whether main storage, transfer pumps, remote level, filtration, fuel management or multi-set supply may be added later.
Typical Operating Tasks
A sub-base tank simplifies the right project; one capacity cannot serve every facility and outage duration
Centralize equipment and day fuel to reduce workload for the facility team
Best for shorter outages with clear refueling access, while nighttime noise, refueling safety, fire controls and regular testing are also addressed.
Reduce fuel pipework in limited service space while preserving target autonomy for fire, security and elevators
Critical loads, outage duration, facility-team capability and delivery-vehicle access all belong in the tank-capacity decision.
Provide compact standby for controls, lighting and auxiliaries; connect a full fuel system for long production duty
Retrofits should verify full-fuel weight, foundation, ventilation, exhaust, service height and external-storage expansion.
Get a sub-base fuel tank recommendation based on generator rating, autonomy and refueling conditions
Share the country and city, generator rating, expected load factor, target hours, open or acoustic structure, site dimensions, refueling method, fire requirements and future external-storage plan. HOHANK engineers will define usable fuel, base structure and fuel interfaces.