Fueling Station Operations Flashcards
7 cards from real CNG practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Fueling Station Operations flashcards as text
A CNG station has adequate compressor capacity, but vehicles are filling very slowly. What is the most likely cause?
Answer: Station storage bank pressures have dropped close to vehicle cylinder pressure
Slow fill occurs when storage bank pressure drops near the vehicle's current onboard pressure, reducing the differential that drives gas flow.
What does 'temperature compensation' mean in the context of CNG dispensing?
Answer: Adjusting measured volume to a standard temperature so customers receive consistent energy content
Temperature compensation corrects the metered volume to a standard reference temperature, ensuring customers receive consistent energy content regardless of ambient temperature.
A CNG vehicle consistently receives only about 75% of a full fill at your station. What is the most likely root cause?
Answer: Station storage bank pressure is lower than the vehicle's remaining onboard pressure
If station storage pressure is lower than the vehicle's current cylinder pressure, gas cannot flow and the vehicle cannot receive a complete fill.
What is the typical pressure configuration for a three-bank CNG cascade storage system?
Answer: 1,200 PSI / 2,400 PSI / 3,600 PSI
A standard three-bank cascade uses low (approx. 1,200 PSI), medium (approx. 2,400 PSI), and high (3,600 PSI) banks, with the low bank drawn first.
What must be done BEFORE reconnecting and pressurizing a CNG compressor after maintenance?
Answer: Leak-test all disturbed connections with an approved method before applying pressure
Every connection disturbed during maintenance is a potential leak point and must be tested with an approved leak-detection method (detector instrument or soap solution) before pressurization.
What is the maximum service pressure for standard CNG vehicle cylinders used in the United States?
Answer: 3,600 PSI (248 bar)
The standard CNG vehicle cylinder service pressure in the US is 3,600 PSI (248 bar), as established by SAE J1616 and ANSI/CSA NGV2 cylinder standards.
Which condition requires an operator to stop fueling a CNG vehicle and refuse further service until an inspection is completed?
Answer: Visible damage, dents, or corrosion on the vehicle's CNG cylinder or fuel lines
Visible physical damage to a CNG cylinder or fuel lines poses a serious explosion hazard; fueling must stop until a qualified technician inspects and clears the vehicle.