Page 66 - AFVi CNG & LNG Participant Guide

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 CNG operation only – no into engine cylinder
diesel on board  Requires diesel as ignition source

NGV Essentials and Safety Practices (CNG & LNG) © 2024 AFVi All Rights Reserved Page 8-8