Page 16 - ESP (CNG) Participant Guide

Module 1: Properties and Characteristics of Natural Gas

Lesson 1.4: How Natural Gas is Stored Onboard Vehicles

How CNG is Stored  Compressed gas
Onboard Vehicles o Low energy density in natural state
 High pressure – nominal 3,600 psi @ 70°F

CNG Cylinder
Pressures Operating Rated Required Maximum
Pressure Pressure Safety Fill
(MAWP) Factor Pressure
Cylinders 3,600 psi 3,600 psi 1.25:1 4,500 psi
@ 70°F

Temperature/  As temperature increases, pressure increases
Pressure  As temperature decreases, pressure decreases
Relationship

Compressing  CNG is natural gas that has been compressed to approximately 3,600 pounds per
Natural Gas square inch (psi)
 One cubic foot of natural gas is compressed into 5.6 cubic inches
 300 times as much energy as natural gas at atmospheric pressure

One cubic foot (uncompressed) One cubic foot (compressed)

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