ASE Compressed Natural Gas (CNG) Vehicles 2

Question 1

What is the typical service pressure of a CNG fuel storage cylinder in a light-duty vehicle?

Accepted Answer

3,600 psi

Answer

150 psi

Answer

600 psi

Answer

9,000 psi

Question 2

Which component reduces high cylinder pressure to a usable pressure before the gas reaches the engine?

Accepted Answer

Fuel pressure regulator

Answer

Catalytic converter

Answer

Throttle body

Answer

Fuel rail damper

Question 3

A CNG cylinder has an expiration date stamped on it. Why must it be removed from service when expired?

Accepted Answer

The composite or steel structure can fatigue and fail under pressure over time

Answer

The fuel quality degrades inside

Answer

It loses its color coating

Answer

The mounting bolts rust

Question 4

What odorant is added to CNG so leaks can be detected by smell?

Accepted Answer

Mercaptan

Answer

Chlorine

Answer

Ammonia

Answer

Ethanol

Question 5

Where does CNG tend to accumulate if it leaks inside an enclosed space?

Accepted Answer

Near the ceiling, because it is lighter than air

Answer

On the floor, because it is heavier than air

Answer

It disperses evenly

Answer

It sinks into drains

Question 6

Which device on a CNG cylinder vents gas to prevent rupture if the tank is exposed to fire?

Accepted Answer

Pressure relief device (PRD)

Answer

Check valve

Answer

Solenoid shutoff

Answer

Fill receptacle

Question 7

Before servicing the CNG fuel system, what is the correct first step?

Accepted Answer

Isolate the cylinder valve(s) and depressurize/purge the lines

Answer

Disconnect the battery only

Answer

Drain the engine oil

Answer

Open the radiator cap