CNG Cylinder Inspection and Regulations 2

Question 1

According to CNG cylinder inspection standards, which condition requires immediate removal from service?

Accepted Answer

A visible crack, burn mark, or bulge anywhere on the cylinder

Answer

Cracks, burn marks, or bulges indicate structural compromise and require immediate cylinder removal from service.

Question 2

Which standard specifically governs the design, testing, and labeling of compressed natural gas vehicle fuel containers in the US?

Accepted Answer

ANSI/NGV-2

Answer

ANSI/NGV-2 is the American National Standard specifically for CNG vehicle fuel containers, covering design, manufacture, and testing.

Question 3

A Type 4 CNG cylinder is best described as having which construction?

Accepted Answer

Plastic (non-metallic) liner fully wrapped with carbon fiber or fiberglass composite

Answer

Type 4 cylinders use a non-metallic plastic liner (typically HDPE) fully overwrapped with composite fiber material, making them the lightest cylinder type.

Question 4

What is the standard maximum service life of a DOT-specification CNG vehicle cylinder from its manufacture date?

Accepted Answer

20 years

Answer

Most DOT-approved CNG cylinders carry a 20-year maximum service life from the stamped manufacture date, after which they must be replaced.

Question 5

What is the primary purpose of hydrostatic pressure testing performed on CNG cylinders?

Accepted Answer

To verify the cylinder can withstand test pressures significantly above service pressure

Answer

Hydrostatic testing subjects the cylinder to pressures well above service pressure (typically 5/3 of service pressure) to verify structural integrity and detect permanent deformation.

(CNG) Compressed Natural Gas Practice Test

(CNG) Compressed Natural Gas Practice Test

CNG Cylinder Inspection and Regulations 2