Generator day-tank fuel and runtime records before integrated systems test

Direct answer

Before a datacenter integrated systems test, the generator fuel record should identify the generator or plant, test script, accepted runtime basis, main tank or belly tank, day tank, usable fuel volume, fuel-level reading source, date and time of reading, tank chart or controller value used, fuel delivery status, day-tank transfer-pump status, H-O-A switch position, lead and lag pump assignment where used, valves, vents, filters, leak checks, fuel condition checks required by the project, fuel alarms, BMS or EPMS points, generator controller runtime hours, and the person who accepted the release.

The record should also show what was actually proven. A day-tank photo by itself does not prove the plant has the required runtime. A bulk-tank gauge by itself does not prove the day tank refills. A fuel delivery ticket by itself does not prove the fuel reached the available tank. Tie the evidence together: measured level, accepted conversion to gallons, usable gallons, expected consumption basis, transfer path, alarm status, leak condition, and release decision.

Do not use a universal runtime, day-tank setpoint, or alarm threshold. The controlling basis comes from the commissioning plan, owner project requirements, generator submittal, fuel-system submittal, project specification, manufacturer instructions, NFPA/AHJ basis where applicable, insurance or reliability standard where applicable, MOP, and site safety plan.

Why this gates IST

Integrated systems testing can place generators, transfer switches, switchgear, UPS systems, controls, cooling, alarms, and operations staff into one timed sequence. If the fuel record is weak, the test team may start a scripted outage sequence without knowing whether the day tank can refill, whether the low-fuel alarm is trustworthy, whether the transfer pumps are in the right mode, or whether a leak has already made the system unfit for a run.

The purpose of the fuel release record is practical. It lets the commissioning agent, electrical contractor, generator vendor, controls team, owner, and operations lead see that fuel readiness was checked before the script started. It also creates a defensible stopping point if the team finds a bad gauge, disabled transfer pump, unacknowledged alarm, closed valve, spill risk, failed float, water in the fuel sample, or mismatch between expected runtime and available fuel.

This is different from a load-bank interval log. A load-bank record shows how the generator performed at each applied load step. The fuel readiness record shows whether the fuel system and documented runtime basis are ready to support the integrated sequence that follows.

Start with the accepted basis

The first line should name the accepted basis for runtime and fuel-system readiness. That may include the commissioning script, MOP, owner project requirements, project specification, approved generator and fuel-system submittals, tank chart, fuel consumption table, factory data, startup report, manufacturer manual, AHJ direction, NFPA 110 classification where applicable, and owner operations requirement.

Be careful with code language. NFPA 110 applicability and class duration depend on the emergency or standby system classification, AHJ, and project basis. Many datacenter generator plants also have owner, insurance, service-level, and reliability requirements that are separate from life-safety code acceptance. The field record should identify the basis used; it should not interpret the code on the fly.

If the project documents specify a day-tank runtime, alarm setpoint, usable capacity, minimum main tank level, refuel trigger, fuel sampling requirement, or transfer-pump test, copy that requirement into the field form by reference. If the field team changes the requirement, record who approved the change and whether IST was allowed to proceed.

Map the tank lineup

A generator fuel record should make the physical lineup obvious. Identify each generator, day tank, belly tank, base tank, main or bulk storage tank, supply line, return line, transfer pump, manual pump where installed, filter, valve, vent, drain, level gauge, sender, float switch, controller point, and alarm point that matters to the test.

For a multi-generator plant, separate shared fuel storage from unit-specific day tanks. Record which generator is served by which tank, which transfer pump feeds which tank, which pump is lead or lag, which valves are open or locked, and which controls point reports to the generator controller, BMS, EPMS, or annunciator.

Do not let a single photo stand in for the lineup. Pair photos with labels: tank ID, generator ID, gauge, controller screen, pump panel, valve tag, alarm screen, and timestamp. A photo packet is useful only when a reviewer can tell which piece of equipment it proves.

Day-tank level is not one number

A strong day-tank entry records the measured level, the source of the measurement, the accepted conversion to gallons, the usable amount, and the time of the reading. A sight glass, controller value, tank monitor, dip reading, sender display, and manual calculation do not have the same uncertainty. Say which one was used.

Usable fuel is not always the same as gross tank volume. The record should account for project limits such as overfill shutoff, low-level alarm, pump-start level, unusable pickup volume, fuel returned to the main tank, day-tank operating band, or manufacturer limit. If the project uses a tank chart or calibrated monitor, attach it or identify its revision.

Where the specification gives example setpoints, keep them tied to that specification. A VA generator specification, for example, describes a day tank with controls for transfer-pump start, low-fuel alarm, second-pump action, and overfill protection, and it gives particular volume points for that project context. That is useful evidence for what a record can capture, not a universal setpoint for every datacenter.

Prove transfer readiness

Fuel in the main tank does not help IST if the transfer path is not available. The release record should show transfer-pump status, H-O-A position, control power, pump alternator status where used, lead and lag assignment, pump test result required by the project, suction and discharge valve status, filter status, leak condition, day-tank float or sender status, and whether the pump actually refilled the day tank when commanded or simulated.

WBDG generator specification language includes field checks for fuel type, fuel level, fuel-line connections, and fuel filters, and it includes day-tank alarm tests for overfill and low-level conditions. Startup checklist material also calls for inspection and testing of day-tank piping, transfer pumps, controls, switches, floats, senders, other tanks, accessories, vents, and priming. Those are the kinds of fields that keep a release from becoming a guess.

If a pump was not tested because IST would use a prefilled day tank only, write that limitation. If the test depends on the bulk tank refilling day tanks during the run, a record that does not prove the transfer path is incomplete.

Alarms need evidence

For IST release, list every fuel alarm that matters to the script. Typical fields include day-tank low level, day-tank critical low level, day-tank high level or overfill, transfer-pump fail, leak detection, rupture basin, low main tank level, fuel filter restriction where monitored, controller common alarm, BMS point, EPMS point, annunciator point, and alarm acknowledgement status.

The record should say whether each point was normal by live status, functionally tested, simulated under the approved procedure, previously tested by an accepted report, or held open as an exception. WBDG test language provides examples of recording day-tank overfill and low-level alarm actuation levels and verifying protective alarm or shutdown devices by simulated actuation.

Do not clear IST with silent alarm assumptions. If a controller screen is normal but the BMS point is mapped wrong, the operations team may miss the problem during the integrated sequence. If the alarm was intentionally disabled for work, record the bypass, owner approval, compensating measure, and restoration check.

Runtime math must be traceable

Runtime should be shown as a field calculation with named inputs, not as a rounded confidence statement. Record the required runtime, load basis, expected generator load, fuel consumption source, usable tank volume, day-tank operating band, main tank level, transfer availability, refuel plan where allowed, and reserve or stop point required by the project.

Use the approved source for fuel burn: generator submittal, manufacturer table, startup report, fuel-system design, owner standard, or commissioning script. If the test will run at a specific projected load, identify that load. If the requirement is based on rated load, do not substitute a lighter expected load unless the commissioning authority and project basis allow it.

Keep the math simple enough to audit. Example fields are accepted usable gallons, expected gallons per hour at the test basis, required hours, calculated available hours, required reserve, and pass or hold decision. If any input is unknown, stale, or disputed, mark the release held or conditional.

Leaks and fuel condition can stop the release

Fuel readiness includes more than quantity. The record should note visible leaks, stains, odors, open drains, containment condition, day-tank breather or vent condition, fuel-line connections, flexible hoses, filters, valves, gauges, spill kits required by the site, and housekeeping around the generator and fuel system.

Manufacturer manuals and startup checklists repeatedly treat leaks, fuel level, transfer pump operation, fuel-line condition, hoses, filters, sediment, vents, and alarms as recurring checks. If the project requires fuel sampling, water draw, polishing status, biocide treatment, delivery ticket review, or tank bottom water check, attach that evidence or identify the accepted report.

Do not operate through a known fuel leak or unsafe fuel condition just because the IST window is hard to schedule. Fuel handling, spill response, fire protection, environmental controls, and generator operation must follow the approved site plan and qualified personnel direction.

Use an auditable table

Use the owner form, commissioning script, manufacturer startup sheet, fuel-system checklist, or project test report first. Add a field table only where the required form does not make fuel readiness easy to audit.

Build a photo packet

Photos should prove the field conditions, not decorate the report. Capture the tank nameplate or tag, gauge or sight glass, controller fuel screen, day-tank panel, transfer-pump panel, H-O-A switch position where visible and allowed, valve tags, vent condition, containment, leak-free connections, alarm screen, BMS or EPMS point, delivery ticket, sample label, and any deficiency correction.

Use consistent labels. A good photo filename or caption includes generator ID, tank ID, item shown, date, time, and photographer. If the camera timestamp is not trusted, place the accepted date and time in the field log instead of relying on image metadata.

Retake photos after corrections. A failed pump, closed valve, low tank level, active alarm, or leak cleanup needs before and after evidence if the team later releases IST. Do not overwrite the failed condition; keep it with the correction record.

Separate release decisions

Generator fuel readiness can release one step without releasing everything. The record should say whether it releases vendor startup, a load-bank run, transfer testing, a black-start drill, a limited dry run, one generator, one lineup, one data hall, or the full integrated systems test.

If the fuel record is accepted with conditions, write the condition plainly. Examples include refuel before starting the full-duration sequence, manual operator stationed at the fuel panel, alarm mapping to be watched locally only, transfer pump retest before live load, sampling report pending, or runtime accepted only at the reduced test load.

A conditional release is not a hidden pass. It should identify the approving person, expiration time, compensating measure, and exact test step that must stop if the condition is not cleared.

Before IST checklist

Run this check before the commissioning agent or owner representative accepts generator fuel readiness for an integrated systems test.

• Confirm generator IDs, tank IDs, IST script, MOP, owner requirement, runtime basis, load basis, and release boundary.
• Record main tank, belly tank, base tank, and day-tank levels with reading source, date, time, tank chart or controller value, gross gallons, and usable gallons.
• Attach the fuel consumption basis used for runtime math: manufacturer table, generator submittal, startup report, owner standard, or commissioning script.
• Calculate available runtime from accepted usable gallons, required hours, expected load or rated-load basis, reserve, and project stop point.
• Verify day-tank transfer pumps, H-O-A position, lead and lag assignment, control power, valve lineup, filters, vents, drains, and refill function required by the project.
• Record fuel alarms and points: low level, critical low, high or overfill, pump fail, leak detection, common alarm, BMS, EPMS, annunciator, and acknowledgement status.
• Document leak and condition checks for tanks, piping, flexible hoses, filters, fittings, vents, containment, stains, odors, spill controls, and housekeeping.
• Attach delivery tickets, fuel sample reports, water draw records, polishing records, or maintenance reports required by the project.
• Capture labeled photos of gauges, controller screens, tank tags, pump panels, valve positions, alarm screens, containment, and corrected deficiencies.
• Write every exception, correction, retest, bypass, disabled alarm, manual watch, pending delivery, disputed reading, or conditional release.
• State the decision: released for IST, released for a limited test only, released with condition, held for correction, or retest required.

Weak and strong records

Weak note: Fuel checked. Generators ready for IST.

That note does not identify the tanks, readings, usable gallons, runtime basis, transfer-pump condition, alarm status, leak check, photos, exceptions, or release boundary.

Stronger note: Generator plant fuel readiness reviewed for IST-DC2 under MOP-EPSS-031 revision 4 and commissioning script CX-IST-011. G-1 through G-4 day tanks, main diesel tank FOT-1, duplex transfer-pump panel FP-1, generator controllers, EPMS points, and BMS alarm summary were checked between 0610 and 0645 on 2026-06-09. Runtime basis used approved generator submittal fuel consumption table GEN-SUB-26-32-13-R8, tank chart FOT-1-TC-03, and owner requirement OPR-EPSS-07 for this IST sequence.

The record lists each tank reading, accepted usable gallons, calculated available hours at the approved test load, day-tank level, transfer-pump H-O-A status, lead and lag pump assignment, valve lineup, low-level and overfill alarm status, common alarm point, fuel-line leak check, containment check, and controller run-time hours. Photos show tank labels, gauges, controller screens, pump panel, valve tags, EPMS alarm screen, delivery ticket, and corrected valve tag on G-3 day-tank return. Issue IST-FUEL-014 remains open for a failed remote high-level point on G-2, with local generator-panel watch accepted by the owner for the dry-run sequence only. Full live-load IST remains held until that alarm point is retested.

The stronger note works because it gives the reviewer equipment IDs, time, readings, basis, exceptions, and the release boundary. It does not turn a partial fuel check into full plant acceptance.

Common mistakes

The first mistake is treating gross tank volume as usable runtime. The record needs the accepted usable volume and stop point.

The second mistake is recording only the main tank. IST can fail because the day tank does not refill, the transfer pump is in the wrong mode, a valve is closed, or a float switch is wrong.

The third mistake is trusting one screen without checking the source. A controller value, tank monitor, sight glass, BMS point, and handwritten gauge reading may not agree. The record should say which source controlled the release.

The fourth mistake is leaving alarm status vague. Fuel alarms need normal, tested, simulated, accepted by previous report, bypassed, or failed status.

The fifth mistake is losing failed attempts. A pump test that failed, alarm that did not report, leak that was cleaned, or fuel delivery that arrived late should stay in the record with the correction.

The sixth mistake is using the fuel record as proof of IST completion. It only supports the decision to proceed with the test scope named in the release.

Questions that come up

How much fuel is enough before IST? Use the approved project basis. The answer may depend on required class or runtime, owner standard, expected test load, reserve, refuel plan, AHJ direction, and whether the test is a dry run or live-load sequence.

Can a fuel delivery ticket prove runtime? Only partly. It can support the quantity record, but the release still needs tank level, usable volume, transfer path, alarm status, and any fuel quality evidence required by the project.

Should every alarm be functionally tested the same day? Use the commissioning script and safety plan. Some alarms may be tested by simulation, some may be accepted by a previous witnessed report, and some may require a live functional test. The record should identify the method.

What if the generator has no separate day tank? State the actual configuration. Use the relevant base tank, belly tank, or direct-feed fuel system fields instead of forcing a day-tank checklist onto the wrong equipment.

Who signs the record? Follow the commissioning plan and contract. Signers may include the generator vendor, electrical contractor, fuel-system contractor, commissioning agent, owner representative, facility operations lead, controls integrator, safety representative, or AHJ depending on scope.

Compliance and safety limits

This field note is not a generator design, fuel-system design, NFPA interpretation, environmental compliance plan, SPCC plan, fire-code approval, manufacturer startup instruction, hazardous-energy procedure, energized-work permit, fuel-transfer procedure, spill-response plan, commissioning script, MOP, AHJ approval, or owner acceptance. The approved project documents, manufacturer instructions, commissioning authority, engineer, AHJ, owner, qualified generator vendor, fuel-system contractor, electrical contractor, operations team, and site safety plan control the work.

Do not use this checklist to bypass lockout/tagout, switching orders, energized-work controls, confined-space rules, fuel handling, hot-work restrictions, fire watch, spill controls, ventilation, exhaust routing, environmental reporting, alarm bypass approval, qualified-person requirements, PPE, or emergency procedures. The record preserves the IST fuel-readiness decision. It does not authorize unsafe operation or unapproved release.

Sources checked

• NFPA, NFPA 110 Standard DevelopmentUsed for official NFPA 110 identity and emergency and standby power system context.
• WBDG, UFGS 26 32 15 Engine-Generator Set Stationary 15-2500 KW, with AuxiliariesUsed for project-specification examples covering fuel type, fuel level, fuel-line connections, day-tank overfill and low-level alarm tests, transfer-pump shutdown checks, and protective alarm verification.
• WBDG, VA 26 32 13 Engine GeneratorsUsed for specification examples covering day tanks, day-tank capacity calculations, vents, drains, gauge glass, float switches, low-fuel alarms, duplex transfer pumps, H-O-A switches, manual pump backup, filters, and piping.
• Cummins, Liquid-Cooled Generator Set Application Manual T-030Used for manufacturer guidance on recurring checks for fuel leaks, fuel level, fuel transfer pump operation, flexible fuel hoses, fuel tank sediment, electrical safety controls, alarms, and day-tank breather maintenance.
• Kohler, 30-600 kW Generator Set Operation Manual TP-6914Used for manufacturer safety language around fuel leaks and spilled fuel, and for controller-display examples such as fuel rate, fuel temperature, fuel used where available, and engine run time.
• Kohler, Understanding NFPA 110Used for plain-language context on EPSS classification, class duration, fuel quantity, fuel maintenance, AHJ/manufacturer coordination, and routine testing.
• AKSA Power Generation, Start-Up Check ListUsed for startup-checklist examples covering adequate fuel supply, no fluid leaks, day-tank piping, transfer pumps, controls, switches, base-tank floats and senders, tank accessories, vents, priming, remote-auto status, and loaded operation values.
• OSHA, 29 CFR 1910.147 The Control of Hazardous EnergyUsed for safety-boundary context when the checklist discusses hazardous-energy controls and lockout/tagout limits.

Related guides