In practice
Standby diesel generators may sit for long periods between outages. Fuel condition becomes part of reliability, not only a tank capacity question. Water, sediment, microbial growth, wrong fuel grade, and blocked filters can all affect starting and loaded operation.
Fuel polishing is not required for every project, but buyers with large tanks, critical standby loads, or long storage periods should discuss filtration and sampling before finalizing the RFQ.
What to confirm about fuel storage
- Main tank and day tank capacity, material, location, and bunding requirement.
- Expected storage period and fuel turnover pattern.
- Filtration, water drain, inspection hatch, and sampling point arrangement.
- Fuel transfer pump control, overflow return, and low-level alarm requirement.
- Maintenance responsibility after commissioning.
Mistakes that cause site problems
- Only runtime is specified, with no mention of fuel quality management.
- The tank has no easy drain or sampling point, making inspection difficult.
- The project expects the generator supplier to include polishing equipment, but it is not listed in the quotation scope.
Fuel system planning table
| Item | Practical check | Document to request |
|---|---|---|
| Storage tank | Capacity, material, drain, inspection access | Tank drawing or scope note |
| Fuel transfer | Pump duty and control logic | Piping and wiring interface |
| Filtration | Primary filter, water separator, optional polishing | Maintenance checklist |
| Testing | Sampling and load test plan | Commissioning record |
Before requesting a quotation
State the expected runtime, storage period, site temperature range, tank location, and whether a fuel polishing unit is required. Ask for the fuel system scope, filter list, maintenance intervals, and commissioning documents.
Questions purchasers often ask
Is fuel polishing always needed for a standby diesel generator?
No. It is mainly considered when fuel is stored for long periods, the tank is large, or the load is critical enough to justify extra fuel-condition control.
What is the simplest fuel check before handover?
Confirm clean fuel, no visible water at drain points, correct filter installation, transfer pump operation, and loaded running under the expected duty condition.
Should the day tank be included in the generator package?
It depends on project scope. The RFQ should state whether the supplier provides the day tank, transfer pump, level controls, and pipework.
What documents help maintenance teams?
Request the fuel system drawing, filter part numbers, drain and sampling instructions, maintenance checklist, and commissioning record.
RFQ notes to include
For a clearer quotation, send the site country, voltage and frequency, duty rating, load list, installation layout, control interface requirements, noise or enclosure expectations, and any drawings already approved by the project engineer. Ask the supplier to state assumptions in writing so commercial comparison is based on the same scope.