EGSA EGSA Fuel Systems and Storage 1 — Questions and Answers
Question 1: According to NFPA 30 and NFPA 110, what is the maximum allowable capacity for a day tank installed inside a building for a diesel generator set?
- 50 gallons
- 100 gallons (Correct answer)
- 250 gallons
- 500 gallons
Correct answer: 100 gallons
NFPA 30 and NFPA 110 permit a maximum day tank capacity of 100 gallons inside a building for diesel-fueled generator sets.
Question 2: What is the primary purpose of a fuel polishing system on a diesel generator installation?
- Increase fuel pressure to the injectors
- Remove water, sediment, and microbial contamination from stored fuel (Correct answer)
- Blend biodiesel additives into the fuel supply
- Reduce fuel temperature before injection
Correct answer: Remove water, sediment, and microbial contamination from stored fuel
Fuel polishing systems circulate stored diesel through filters and water separators to remove contaminants that degrade fuel quality over time.
Question 3: Which ASTM standard governs the specification for diesel fuel used in standby generator applications in the US?
- ASTM D975 (Correct answer)
- ASTM D396
- ASTM D4814
- ASTM D2880
Correct answer: ASTM D975
ASTM D975 is the standard specification for diesel fuel oils, including No. 2-D commonly used in standby generator sets.
Question 4: What microbial growth condition is commonly found in diesel fuel storage tanks and can clog filters and damage fuel systems?
- Algae bloom
- Sulfate-reducing bacteria and fungi at the fuel-water interface (Correct answer)
- Aerobic yeast in the vapor space
- Iron-oxidizing bacteria near the tank vent
Correct answer: Sulfate-reducing bacteria and fungi at the fuel-water interface
Sulfate-reducing bacteria and fungi thrive at the diesel-water interface in storage tanks, forming biomass that clogs filters and corrodes tanks.
Question 5: What is the recommended maximum storage life for diesel fuel in a properly maintained and sealed tank before polishing or testing is required?
- 6 months
- 12 months (Correct answer)
- 24 months
- 5 years
Correct answer: 12 months
Diesel fuel has a practical storage life of approximately 12 months; beyond that, oxidation and microbial growth degrade fuel quality unless treated or polished.
Question 6: Which type of fuel tank is most commonly required for generator installations at critical facilities to meet NFPA 110 Level 1 requirements?
- Single-wall above-ground steel tank
- Double-wall sub-base or underground tank with leak detection (Correct answer)
- Fiberglass-reinforced plastic open-top tank
- Galvanized steel day tank with no containment
Correct answer: Double-wall sub-base or underground tank with leak detection
NFPA 110 Level 1 facilities require fuel tanks with secondary containment and leak detection, typically double-wall construction, to prevent fuel loss and environmental contamination.
EGSA EGSA Fuel Systems and Storage 1
According to NFPA 30 and NFPA 110, what is the maximum allowable capacity for a day tank installed inside a building for a diesel generator set?