Page 25 - AFVi CNG & LNG Participant Guide

Module 2: High-Pressure CNG Fuel System Components

Pressure Relief
Devices (PRDs) and
Vent Lines

PRDs Vent Lines
 PRDs protect cylinder from rupture during fire
o Each cylinder must have at least one PRD
 Vent caps required

Fuel System  Isolate shigh-pressure fuel during a fuel line break
Isolation Solenoid  Opens when the engine is in its startup sequence
Valve

Fuel System  Allows first responders to shut off gas to engine in an
Isolation Manual emergency
Valve  Also known as manual or quarter turn shutoff
 Used to isolate the cylinder or cylinders from the remainder
of the high-pressure fuel system for maintenance and repair
of downstream components
 If valve is too stiff to turn by hand, it should be replaced

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