Half/Pack
®
Issued April 2018
Compressed Natural Gas (CNG) Option
Copyright 2018, Heil Environmental
Printed in the U.S.A.
Compressed Natural Gas (CNG) Option
179
COMPRESSED NATURAL GAS (CNG) FUEL MODULE
A. Fuel Module Functions
The CNG fuel tanks contain CNG at a pressure of 3,600 psi in USA, (3,000 psi in Canada). The CNG Fuel Module
serves multiple functions within a natural gas vehicle (NGV) fuel system.
These functions include:
Storage tank refueling
Storage tank pressure measurement
Manual and ignition controlled fuel shut-off
Pressure reduction from storage tanks to engine supply
Fuel system filtration
Liquid removal from fuel system
B. Fuel Module Components
The images on the following pages show a typical CNG system configuration. Your CNG system configuration may vary.
1. High Pressure Gauge
The high pressure gauge, located in the front panel of the fuel control module, indicates the pressure of the CNG
being supplied to the regulator. If the manual shut-off valve is turned to ‘on’ and all other valves are open between
the fuel tank and the fuel control module, this gauge reflects fuel tank pressure.
2. Low Pressure Gauge
Located below the high pressure gauge in the front panel of the fuel control module, the low pressure gauge
indicates the pressure of the CNG leaving the regulator and supplying the vehicle’s engine. A typical reading for this
gauge is 100-120 psi, dependent upon regulator setting.
3. Manual Shut-Off Valve
The manual shut-off valve is located on the bottom front of the fuel control module. Rotate the handle clockwise so
arrow turns down and points to the ‘OFF’ position; fuel flow from the tanks to the vehicle’s engine is prohibited.
Rotate the handle counterclockwise so arrow points to the ‘ON’ position to allow fuel flow from the tanks to the
vehicle’s engine.
Figure 32. Manual Shut-Off Valve
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