Page 16 - CNG ESP Participant Guide2024
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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         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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