Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
---
title: Facility Fuel-Oil Systems
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### Where the system serves emergency or standby power, it shall additionally comply with NFPA 110 and NFPA 37.
−### Aggregate aboveground storage exceeding 1,320 gallons, or aggregate underground storage exceeding 42,000 gallons, shall require a SPCC Plan under 40 CFR 112. {note}
+### Aggregate aboveground storage exceeding 1,320 gallons, or aggregate underground storage exceeding 42,000 gallons, shall require a SPCC Plan under 40 CFR 112.
### The designer shall verify whether the cumulative capacity of all bulk, day, and sub-base tanks on the site exceeds the SPCC threshold; multiple generator sub-base tanks frequently exceed 1,320 gallons in aggregate without the threshold being recognized.
−### The Contractor shall obtain all state and local UST permits before underground tank installation. {note}
+### The Contractor shall obtain all state and local UST permits before underground tank installation.
### Underground storage tanks are regulated under state programs authorized by RCRA Subtitle I; the Contractor shall register the tank and provide proof of registration in the closeout submittals.
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### The system shall be designed for No. 2 distillate fuel oil conforming to ASTM D975 Grade No. 2-D.
−### Where ultra-low-sulfur diesel (ULSD) is the supplied fuel, all wetted elastomers shall be compatible with ULSD. {note}
+### Where ultra-low-sulfur diesel (ULSD) is the supplied fuel, all wetted elastomers shall be compatible with ULSD.
### ULSD has lower lubricity and different solvency than legacy No. 2 fuel oil; seals, gaskets, and flexible connectors carried over from legacy details may swell, harden, or fail. Fluoroelastomer (FKM) seals are preferred for ULSD service.
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## Climate {toc}
−### No. 2 fuel oil begins to precipitate wax near its cloud point, approximately -7 °C (20 °F); systems in cold climates shall include freeze and gel protection. {note}
+### No. 2 fuel oil begins to precipitate wax near its cloud point, approximately -7 °C (20 °F); systems in cold climates shall include freeze and gel protection.
### Where the design ambient temperature can approach or fall below the fuel cloud point, the system shall include tank heating or pipe trace heating to keep fuel above its gel point.
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### Where the bulk tank cannot satisfy the engine fuel-supply pressure and lift limits directly, the system shall include a day tank fed by a fuel transfer pump set.
−### The day tank proximity, capacity, and fill controls shall comply with the day-tank provisions of NFPA 110 for emergency and standby applications.
−
−## Selecting the tank arrangement is the first architectural decision and drives containment strategy, fire-code setbacks, and the transfer pump scope. {note}
−
```datasheet
label: System architecture
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```
+### The day tank proximity, capacity, and fill controls shall comply with the day-tank provisions of NFPA 110 for emergency and standby applications.
+
+## Selecting the tank arrangement is the first architectural decision and drives containment strategy, fire-code setbacks, and the transfer pump scope. {note}
+
## Tank Location {toc}
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## Tank Type {toc}
−### The tank type, aboveground or underground, shall be selected based on site constraints, regulatory burden, and fire-code setbacks. {note}
+### The tank type, aboveground or underground, shall be selected based on site constraints, regulatory burden, and fire-code setbacks.
### Aboveground tanks are easier to inspect and monitor but consume site area and are subject to fire-code setbacks; underground tanks free the site but add corrosion-protection, leak-monitoring, and permitting obligations.
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## Tank Construction {toc}
−### Tanks shall be double-wall construction with continuous interstitial monitoring unless the AHJ accepts single-wall construction within an external secondary containment structure. {note}
+### Tanks shall be double-wall construction with continuous interstitial monitoring unless the AHJ accepts single-wall construction within an external secondary containment structure.
### Double-wall tanks satisfy SPCC secondary containment without a separate dike and provide a monitored interstitial space; single-wall tanks require an external containment structure and are prohibited by many jurisdictions.
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## Tank Capacity {toc}
−### The bulk tank capacity shall be sized to provide the facility's required on-site fuel runtime at full rated load. {note}
+### The bulk tank capacity shall be sized to provide the facility's required on-site fuel runtime at full rated load.
### For NFPA 110 emergency and standby systems, the runtime requirement is set by the system Class; Class 96 requires 96 hours of fuel at full rated load and is the most demanding common case.
−### The bulk tank shall be sized to hold not less than 133 percent of the fuel required for the full-rated-load runtime period. {note}
+### The bulk tank shall be sized to hold not less than 133 percent of the fuel required for the full-rated-load runtime period.
### NFPA 110 requires the main tank to hold 133 percent of the fuel needed for the rated runtime; sizing the tank to only the bare runtime volume leaves no usable design margin and no allowance for unpumpable bottoms.
−### The day tank shall be sized for not less than the engine or burner supply duration required by the prime mover, commonly an 8-hour supply at full load. {note}
+### The day tank shall be sized for not less than the engine or burner supply duration required by the prime mover, commonly an 8-hour supply at full load.
```datasheet
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## Tank Configuration {toc}
−### The bulk tank geometry shall suit the available footprint; horizontal cylindrical, vertical cylindrical, and rectangular configurations are all acceptable for listed tanks. {note}
+### The bulk tank geometry shall suit the available footprint; horizontal cylindrical, vertical cylindrical, and rectangular configurations are all acceptable for listed tanks.
### A sub-base tank shall be dimensionally compatible with the generator base rail, and its fill, supply, and return port locations shall match the generator set. {note}
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## Secondary containment confines a tank or piping leak to a defined, impervious volume so that released fuel is recovered rather than reaching soil, groundwater, or storm drains. It may be provided by the tank's integral double wall, by an external dike or berm, or by a lined concrete basin. {note}
−### Secondary containment shall be sized for not less than 100 percent of the capacity of the largest single tank served, plus freeboard for precipitation where the containment is exposed to weather. {note}
+### Secondary containment shall be sized for not less than 100 percent of the capacity of the largest single tank served, plus freeboard for precipitation where the containment is exposed to weather.
### A common rule of thumb of 110 percent of tank volume does not satisfy 40 CFR 112 in high-rainfall regions; the containment shall be sized for the full largest-tank volume plus calculated precipitation freeboard.
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## Filtration and Water Separation {toc}
−### Fuel shall pass through filtration and water separation between the bulk tank and the prime mover. {note}
+### Fuel shall pass through filtration and water separation between the bulk tank and the prime mover.
### Modern high-pressure injection equipment is intolerant of particulate and water; filtration protects the injectors and the day-tank fuel quality.
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## Fuel Polishing {toc}
−### Fuel stored for extended periods shall be maintained by a fuel polishing system. {note}
+### Fuel stored for extended periods shall be maintained by a fuel polishing system.
### Fuel sized for a 96-hour runtime at a low daily consumption rate may sit in the tank for months; ULSD absorbs more water and supports microbial growth faster than legacy diesel, so static long-term storage degrades fuel quality if it is not maintained.
−### Where the design fuel turnover exceeds approximately 30 days, the system shall include a dedicated fuel polishing skid with multi-stage filtration, water separation, and continuous or scheduled recirculation. {note}
+### Where the design fuel turnover exceeds approximately 30 days, the system shall include a dedicated fuel polishing skid with multi-stage filtration, water separation, and continuous or scheduled recirculation.
### NFPA 110 does not name fuel polishing directly, but its fuel-quality maintenance requirement implies it for extended-storage generator fuel; omitting polishing, biocide dosing, and water-bottom monitoring is a common reliability defect.
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## Leak detection identifies a release into the interstitial space or containment before fuel escapes the system; overfill prevention stops a fill before the tank is overtopped. {note}
−### The interstitial space of every double-wall tank and double-containment pipe shall be continuously monitored for leaks. {note}
+### The interstitial space of every double-wall tank and double-containment pipe shall be continuously monitored for leaks.
### EPA UST regulations and many state AST regulations require continuous interstitial monitoring; treating leak detection as an optional add-on creates code non-compliance and inspection failures.
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## Tank level monitoring provides the operating level for fill scheduling, fuel inventory, and the low-level alarms that protect the prime mover. {note}
−### Underground storage tanks shall be equipped with an automatic tank gauge (ATG) with continuous electronic level monitoring. {note}
+### Underground storage tanks shall be equipped with an automatic tank gauge (ATG) with continuous electronic level monitoring.
### State and EPA UST regulations require continuous electronic inventory and leak monitoring on underground tanks; a mechanical float gauge alone does not satisfy these programs.
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## Piping Material {toc}
−### Fuel oil supply and return piping shall be black steel, Schedule 40, with welded, threaded, or flanged joints, unless another material is specifically permitted below. {note}
+### Fuel oil supply and return piping shall be black steel, Schedule 40, with welded, threaded, or flanged joints, unless another material is specifically permitted below.
### Black steel Schedule 40 with 150-pound fittings is the standard fuel oil piping; copper and double-containment piping are alternatives for specific conditions.
−### Copper tubing may be used for heating-oil supply lines up to 2 inches only where permitted by the AHJ; the designer shall verify the AHJ accepts copper for the fuel in service before specifying it. {note}
+### Copper tubing may be used for heating-oil supply lines up to 2 inches only where permitted by the AHJ; the designer shall verify the AHJ accepts copper for the fuel in service before specifying it.
### NFPA 31 permits copper for heating oil up to 2 inches, but some AHJs prohibit copper for diesel; copper shall not be specified without confirming local acceptance.
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## Piping Arrangement {toc}
−### Return piping shall terminate below the minimum operating fuel level in the tank. {note}
+### Return piping shall terminate below the minimum operating fuel level in the tank.
### A return line that discharges above the fuel surface foams and aerates the fuel and entrains air into the transfer pumps; the return shall be extended below the minimum fuel level.
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# Boiler and Burner Interface {toc}
−## Oil-fired burners require a specific fuel pressure and flow at the burner inlet; the transfer pump and regulating valve must deliver exactly that. {note}
+## Oil-fired burners require a specific fuel pressure and flow at the burner inlet; the transfer pump and regulating valve must deliver exactly that.
−### The fuel supply pressure and flow at the burner inlet shall match the burner manufacturer's requirements. {note}
+### The fuel supply pressure and flow at the burner inlet shall match the burner manufacturer's requirements.
### Burner fuel pressure requirements are frequently left to the burner contractor without a clear responsibility assignment; the transfer pump curve and the pressure-regulating valve shall be matched to the burner specification, and this responsibility shall be assigned in the contract documents.
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# Installation {toc}
−## Aboveground tanks shall be installed on foundations and supports designed for the full tank weight per PEI RP200 and the structural drawings. {note}
+## Aboveground tanks shall be installed on foundations and supports designed for the full tank weight per PEI RP200 and the structural drawings.
### Underground tanks shall be installed with the bedding, backfill, anchoring, and deflection control required by the tank manufacturer and UL listing. {note}
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- Spare gaskets and FKM seals
```