Page 66 - CNG/ LNG ESP Participant Guide 2024

Module 8: LNG Vehicle Systems and Safety Practices

Methane Detection
System

▪ Two Zones
o Engine compartment
o Cab

Lesson 8.3: Unsaturated LNG Fuel Systems and Components

What is ▪ LNG that has NOT been slightly warmed at the LNG station by heat exchanger(s)
Unsaturated LNG? ▪ Unsaturated fuel is colder than saturated
o Saturated refers to the amount of heat that has been absorbed by the fuel

Comparing Saturated Unsaturated
Saturated and (Warmed ~ -200⁰F) (Cold ~ -230⁰F)
Unsaturated LNG ▪ No accumulator ▪ Accumulator required
▪ LNG storage tank ▪ LNG storage tank with pump
▪ Fuel delivered via tank pressure ▪ Fuel delivered via pump
▪ Tank pressure created by warming mechanism
the fuel ▪ Pump mechanism operated by
▪ Low pressure into airstream engine’s power steering pump
▪ Requires an ignition system ▪ High pressure direct injection
▪ Dedicated LNG operation only – no into engine cylinder
diesel on board ▪ Requires diesel as ignition source

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