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
What is the primary purpose of a breakaway coupling on a CNG fueling hose?
Answer: To automatically disconnect if a vehicle drives away with the nozzle attached
A breakaway coupling automatically separates the hose if a vehicle drives off without disconnecting the nozzle, preventing hose damage and uncontrolled gas release.
In a CNG cascaded storage system, which bank is drawn from FIRST to fill a vehicle?
Answer: The low-pressure bank
Cascade systems draw from the low-pressure bank first to maximize storage efficiency, then switch to higher-pressure banks as the differential decreases.
What is the standard CNG fueling pressure for most light-duty vehicles in the United States?
Answer: 3,600 PSI
The US standard CNG service pressure is 3,600 PSI (248 bar), established by SAE and ANSI/CSA NGV standards for light-duty and most heavy-duty applications.
What does a priority panel control in a CNG fueling station?
Answer: Which storage bank is used to fill a vehicle at each stage of fueling
A priority panel directs gas flow from the lowest-pressure storage bank first, then automatically switches to higher banks as pressure differentials decrease.
What does frost or ice forming on the exterior of a CNG storage cylinder most likely indicate?
Answer: A gas leak causing rapid expansion and temperature drop
Frost on a CNG cylinder indicates rapid gas escape causing Joule-Thomson cooling; this is a leak warning that requires immediate shutdown and inspection.
How does a significant rise in gas temperature affect the amount of CNG energy delivered during a fill?
Answer: Less energy (mass) is delivered for the same dispensed volume
Warmer gas is less dense, so at the same pressure and volume, fewer molecules (and therefore less energy) are dispensed.
Which standard governs the nozzle-to-receptacle interface for CNG vehicle fueling in the United States?
Answer: ANSI/CSA NGV1
ANSI/CSA NGV1 specifies the design and performance requirements for CNG fueling nozzles and vehicle receptacles to ensure compatibility.