CNG Fueling Station Operations 2

Question 1

What is the primary purpose of a breakaway coupling on a CNG fueling hose?

Accepted Answer

To automatically disconnect if a vehicle drives away with the nozzle attached

Answer

A breakaway coupling automatically separates the hose if a vehicle drives off without disconnecting the nozzle, preventing hose damage and uncontrolled gas release.

Question 2

In a CNG cascaded storage system, which bank is drawn from FIRST to fill a vehicle?

Accepted Answer

The low-pressure bank

Answer

Cascade systems draw from the low-pressure bank first to maximize storage efficiency, then switch to higher-pressure banks as the differential decreases.

Question 3

What is the standard CNG fueling pressure for most light-duty vehicles in the United States?

Accepted Answer

3,600 PSI

Answer

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.

Question 4

What does a priority panel control in a CNG fueling station?

Accepted Answer

Which storage bank is used to fill a vehicle at each stage of fueling

Answer

A priority panel directs gas flow from the lowest-pressure storage bank first, then automatically switches to higher banks as pressure differentials decrease.

Question 5

What does frost or ice forming on the exterior of a CNG storage cylinder most likely indicate?

Accepted Answer

A gas leak causing rapid expansion and temperature drop

Answer

Frost on a CNG cylinder indicates rapid gas escape causing Joule-Thomson cooling; this is a leak warning that requires immediate shutdown and inspection.

(CNG) Compressed Natural Gas Practice Test

(CNG) Compressed Natural Gas Practice Test

CNG Fueling Station Operations 2