CNG Properties and Safety 3

Question 1

What is the Upper Flammability Limit (UFL) of methane in air?

Accepted Answer

15%

Answer

10%

Answer

20%

Answer

25%

Question 2

Which organization sets the standards for CNG cylinder design and testing in the United States?

Accepted Answer

DOT

Answer

EPA

Answer

NFPA

Answer

OSHA

Question 3

What does the PRD (Pressure Relief Device) on a CNG cylinder do?

Accepted Answer

Releases gas if cylinder temperature or pressure becomes excessive

Answer

Prevents overfilling during fueling

Answer

Shuts off fuel flow when the engine is off

Answer

Measures remaining fuel quantity

Question 4

What is the autoignition temperature of methane?

Accepted Answer

537°C (999°F)

Answer

300°F (149°C)

Answer

200°C (392°F)

Answer

700°C (1292°F)

Question 5

In a CNG fueling station, what is the purpose of a cascade storage system?

Accepted Answer

To store gas at multiple pressure levels for efficient sequential filling

Answer

To cool the gas before dispensing

Answer

To filter contaminants from the gas supply

Answer

To measure dispensed fuel volume accurately

Question 6

When a CNG vehicle is involved in a collision, what is the first safety concern regarding the fuel system?

Accepted Answer

High-pressure gas release or cylinder integrity

Answer

Fuel contamination of the ground

Answer

Fuel igniting from catalytic converter heat

Answer

Battery sparks igniting fuel vapors

Question 7

Which gas is added to CNG to give it a detectable odor for leak identification?

Accepted Answer

Mercaptan (odorant)

Answer

Hydrogen sulfide

Answer

Carbon monoxide

Answer

Ammonia