CNG Properties and Safety 4

Question 1

What is the approximate energy content of CNG compared to gasoline on a volume basis?

Accepted Answer

One gasoline gallon equivalent (GGE) of CNG contains about the same energy as one gallon of gasoline

Answer

CNG contains more energy per gallon equivalent than gasoline

Answer

CNG contains about half the energy of gasoline per GGE

Answer

CNG contains twice the energy of gasoline per GGE

Question 2

CNG cylinders must undergo periodic requalification testing. What is the standard requalification interval for most CNG cylinders?

Accepted Answer

Every 10 years or per manufacturer specification

Answer

Every 1 year

Answer

Every 3 years

Answer

Every 5 years

Question 3

What type of ventilation is required for enclosed spaces where CNG vehicles are parked or serviced?

Accepted Answer

High-level or ceiling ventilation to prevent methane accumulation

Answer

Floor-level exhaust ventilation to remove heavy vapors

Answer

No special ventilation is needed since CNG is non-toxic

Answer

Forced air at mid-level to circulate the space

Question 4

What does 'CNG equivalent' mean when comparing fuel economy ratings?

Accepted Answer

Fuel economy expressed in miles per gasoline gallon equivalent (mpgge)

Answer

The CNG vehicle's range is equivalent to a diesel vehicle

Answer

The vehicle can use both CNG and gasoline interchangeably

Answer

CNG and gasoline vehicles have the same horsepower output

Question 5

Which NFPA standard specifically covers compressed natural gas vehicular fuel systems?

Accepted Answer

NFPA 52

Answer

NFPA 70

Answer

NFPA 30

Answer

NFPA 58

Question 6

When should a CNG cylinder be immediately removed from service?

Accepted Answer

If it has been involved in a fire or shows signs of heat damage

Answer

After being exposed to outdoor temperatures below 32°F

Answer

After accumulating 10,000 fueling cycles

Answer

When the vehicle reaches 100,000 miles

Question 7

What is the primary hazard of CNG in an enclosed space without adequate ventilation?

Accepted Answer

Asphyxiation from oxygen displacement and explosion risk

Answer

Toxic poisoning from methane inhalation

Answer

Skin irritation from direct contact with the gas

Answer

Corrosion of metal surfaces in the enclosure