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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 ▪ 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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