CNG Vehicles 101

It is important that individuals operating a compressed natural gas (CNG) fuel dispenser know the properties of CNG and be trained on the procedures for safely filling a CNG-fueled vehicle.  Follow all operating instructions provided by the  facility.  Always inspect receptacle and equipment. 

What is CNG?


An odorless, nontoxic, gaseous mixture of   hydrocarbons — predominantly methane; stored in a compressed state, at a pressure of 3,000 to 3,600 pounds per square inch.
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How Safe is CNG?

  • CNG has a narrow flammability range.  It is far more likely that either gasoline or diesel would ignite than natural gas. 
  • Natural gas is non-toxic, non-corrosive, and will not contaminate groundwater. 
  • Compared to gasoline, CNG reduces carbon monoxide emissions by 90-97%, nitrogen oxide by up to 60%, and hydrocarbon by 50-75%. 
  • CNG storage cylinders are subjected to ‘severe abuse’ tests that include heat and pressure extremes, gunfire, collisions, and fires before they can pass inspections. 
  • Natural gas is lighter than air and will dissipate rapidly rather than pool in one place.

Fueling Procedures
 


  Before Fueling:

  • Turn off your vehicle
  • Put out all smoking materials
  • Locate an emergency stop button
STEP 1: PREPARE THE CONNECTION
Remove the dust cap from the vehicle’s fueling connection receptacle.  The service pressure of the vehicle’s CNG system—3,600 psi or 3,000 psi—is listed on the label next to the fueling connection receptacle.
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STEP 2: CONNECT THE TRANSFER HOSE
Retract the sleeve on the nozzle and connect the CNG transfer hose to the fueling connection receptacle on the vehicle.  Turn the valve to “FILL.“
 

STEP 3: FILL THE TANK

Lift the dispenser handle to begin fueling.  Run the vehicles gas card using your fuel account number and enter the vehicle odometer reading.  Stand away from dispenser while refueling.
STEP 4: FILLING
Intermittent pauses are a normal part of the filling cycle. Fueling will stop when the target pressure for you tank is reached.  


STEP 5: AFTER FILLING
Disconnect the nozzle by pulling back on the collar of the connector and hang the hose on the dispenser.  A brief hissing or popping sound may be heard when the nozzle is disconnected from the fueling receptacle.


STEP 6: CLOSE THE CONNECTION
 
Replace the dust cap on the vehicle’s fueling connector receptacle, to keep out dirt and moisture.

 

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IN CASE OF EMERGENCY

Fire: Move to a safe place, call 911
Fires at CNG fueling stations are very rare due to safety enhancements and natural gas’s narrow flammability range.  In the unlikely event of fire, please move to a safe place and call 911.

Loud Popping Sound: Push emergency stop button
Pressure release devices relieve gas pressure buildup, consequently producing a loud popping sound.  While this is not an immediate safety concern, please push the emergency stop button, call 254-298-5158.

Very Strong Natural Gas Smell: Push emergency stop button
If you detect an unusually strong odor of gas, see gas venting, or hear a steady hissing sound, push the emergency stop button, call 254-298-5158.