EGSA EGSA Fuel Systems and Storage 2 — Questions and Answers
Question 1: What is the function of a fuel transfer pump in a generator fuel system?
- Inject fuel directly into the engine cylinders at high pressure
- Transfer fuel from the main bulk tank to the day tank or base tank (Correct answer)
- Regulate fuel pressure at the return line
- Circulate fuel through the fuel polishing filters only
Correct answer: Transfer fuel from the main bulk tank to the day tank or base tank
Fuel transfer pumps move diesel from a remote bulk storage tank to the generator's day tank or sub-base tank, ensuring adequate fuel supply during extended operation.
Question 2: When sizing a day tank for a diesel generator set, which factor is most critical to determine tank capacity?
- Generator nameplate kW rating
- Engine fuel consumption rate at full load multiplied by required runtime (Correct answer)
- Fuel tank color and material compatibility
- Distance from the bulk tank to the generator
Correct answer: Engine fuel consumption rate at full load multiplied by required runtime
Day tank capacity is determined by multiplying the engine's full-load fuel consumption rate (gal/hr) by the required autonomous runtime to ensure continuous operation.
Question 3: What is the purpose of a fuel return line on a diesel engine generator set?
- Supply backup fuel if the primary line fails
- Return excess fuel and heat from the injection system back to the tank (Correct answer)
- Circulate fuel through the oil cooler
- Connect the day tank overflow to the main tank
Correct answer: Return excess fuel and heat from the injection system back to the tank
Diesel injection systems deliver more fuel than the engine consumes; the return line routes excess heated fuel back to the tank, requiring consideration of tank temperature rise.
Question 4: Which fuel additive type is used in cold climates to prevent diesel fuel from gelling and clogging fuel filters?
- Cetane booster
- Cold flow improver (anti-gel additive) (Correct answer)
- Biocide
- Corrosion inhibitor
Correct answer: Cold flow improver (anti-gel additive)
Cold flow improvers lower the cold filter plugging point (CFPP) of diesel fuel, preventing wax crystal formation that can block filters in cold weather.
Question 5: What does the Cloud Point of diesel fuel indicate?
- The temperature at which fuel ignites spontaneously
- The temperature at which wax crystals begin to form, clouding the fuel (Correct answer)
- The maximum storage temperature allowed by NFPA 30
- The point at which fuel viscosity exceeds injection pump limits
Correct answer: The temperature at which wax crystals begin to form, clouding the fuel
The cloud point is the temperature at which dissolved wax begins to crystallize and cloud diesel fuel, signaling the onset of cold-temperature operability issues.
Question 6: What is the recommended practice for fuel tank bottom water removal to prevent microbial growth and corrosion?
- Add water absorbing fuel additives monthly and leave water in place
- Drain accumulated water from tank sumps periodically as part of routine maintenance (Correct answer)
- Install a continuous water injection system to dilute contamination
- Seal the tank vent to prevent moisture ingress from humidity
Correct answer: Drain accumulated water from tank sumps periodically as part of routine maintenance
Periodic draining of water from tank sumps removes the water layer that supports microbial growth and causes corrosion on tank walls and fuel system components.
EGSA EGSA Fuel Systems and Storage 2
What is the function of a fuel transfer pump in a generator fuel system?