CNG Fuel System Components 2

Question 1

What is the primary function of a CNG pressure regulator in the fuel system?

Accepted Answer

Reduce high-pressure gas to a usable engine inlet pressure

Answer

The pressure regulator steps down the high storage pressure (up to 3,600 psi) to the low pressure required by the engine's fuel injection system.

Question 2

Which material is most commonly used for CNG high-pressure fuel lines between the cylinder and the regulator?

Accepted Answer

Stainless steel tubing

Answer

Stainless steel tubing is used for high-pressure CNG lines because it resists corrosion and can safely handle pressures up to 3,600 psi.

Question 3

A CNG manual shutoff valve is typically located:

Accepted Answer

At the cylinder valve or close to the storage tank

Answer

The manual shutoff valve is placed at or near the cylinder to allow technicians to isolate the fuel supply during service or in an emergency.

Question 4

What does a CNG fuel filter primarily remove from the gas stream?

Accepted Answer

Particulates, oil mist, and moisture

Answer

CNG filters remove solid particles, compressor oil mist, and water vapor that could damage regulators, injectors, and other precision components.

Question 5

In a bi-fuel CNG vehicle, the gasoline and CNG fuel systems are connected through:

Accepted Answer

A fuel selector switch and dedicated solenoid valves

Answer

A bi-fuel system uses a selector switch to open and close solenoid valves, directing fuel flow from either the CNG or gasoline system to the engine.

(CNG) Compressed Natural Gas Practice Test