Page 60 - AFVi CNG & LNG Participant Guide

Module 8: LNG Vehicle Systems and Safety Practices

Lesson 8.1: Two Types of LNG Fuel Systems

Saturated LNG  Make up approximately 90% of all LNG systems operating today
Systems  “Saturated” refers to the amount of heat that has been absorbed by the fuel
 Also known as “conditioned”
 LNG is warmed to approximately -200 F, 100 psi
o
 Supply fuel for Cummins natural gas engines

Unsaturated LNG  Make up approximately 10% of LNG systems operating today
Systems  Also known as “unconditioned”
o
 Fuel is cold approximately -230 F, approximately 30 psi
 Supply fuel for Westport 15 L HPDI engines (discontinued)

Lesson 8.2: Saturated LNG Fuel Systems and Components

LNG Tank-
Saturated

 Tank within a tank
 Insulated primarily by vacuum
 230 psi maximum pressure
o Vapor pressure serves as fuel pump to move the fuel from the tank to the engine
 Approximately -200 F during fill
o

Saturated LNG  Pressure (up to 230 psi) created as fuel warms in the tank, forces LNG to vaporize
Operation  Vaporizer uses warmth from engine coolant to vaporize LNG to low-pressure natural
gas
 Low-pressure natural gas travels through regulator to engine

Components of  Fill connector
Saturated LNG  Fuel storage tank
System o Manual valves: liquid, vent
o Primary/secondary pressure relief valves
o Fuel gauge sender
o Pressure control (economizer) valve
o Internal check valve
 Engine coolant heat exchanger
 Overpressure regulator
 Automatic Fuel Shutoff Valve
 Methane Detection System

NGV Essentials and Safety Practices (CNG & LNG) © 2024 AFVi All Rights Reserved Page 8-2