Operation and Service of Natural Gas Systems
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Questions and Answers

What is the primary cause of damage to converters?

  • Freezing of engine coolant (correct)
  • Low fuel pressure
  • High fuel pressure
  • Overheating of the converter

    • What is the primary component of Compressed Natural Gas (CNG)?

  • Butane
  • Propane
  • Ethanol
  • Methane (correct)

    • What component within the converter allows for expansion of the coolant if it should freeze?

  • Diaphragm
  • Flexible gasket (correct)
  • Pressure relief valve
  • Spring

    • Which alternative fuel has the highest power factor?

    <p>M85</p> Signup and view all the answers

    What substance is the primary component of natural gas?

    <p>Methane</p> Signup and view all the answers

    What is the typical form of Liquefied Petroleum Gas (LPG)?

    <p>Liquid</p> Signup and view all the answers

    What is the approximate molecular weight of natural gas?

    <p>16</p> Signup and view all the answers

    How is a leak detected in a natural gas system?

    <p>By odor detection using an added odorant</p> Signup and view all the answers

    Which of the following alternative fuels is derived from corn, other grains, and agricultural waste?

    <p>E85</p> Signup and view all the answers

    What are the two main types of fuel delivery systems used in compressed-gas engines?

    <p>Carburetor air-fuel mixer systems and electronic fuel injection (EFI) systems</p> Signup and view all the answers

    What is the typical ignition temperature range of natural gas fuels, compared to gasoline?

    <p>Higher than gasoline</p> Signup and view all the answers

    Which state holds about one-third of America's natural gas reserves?

    <p>Texas</p> Signup and view all the answers

    What must be maintained, besides temperature, for Liquefied Natural Gas (LNG) to remain in liquid form?

    <p>Pressure</p> Signup and view all the answers

    Which of these options correctly lists the octane rating in increasing order?

    <p>Gasoline, LP-Gas, Natural Gas</p> Signup and view all the answers

    Which of the following is NOT specified by the National Fire Protection Association (NFPA) as a component of a CNG fuel system?

    <p>Fuel pump</p> Signup and view all the answers

    What is the main reason that using LP-Gas and CNG can increase the interval between oil changes?

    <p>The fuels are &quot;dry&quot; and do not dilute engine oil</p> Signup and view all the answers

    What is the primary function of solenoid valves in a bi-fuel system?

    <p>To switch between gasoline and compressed gas.</p> Signup and view all the answers

    Where is the air-fuel mixer located in a bi-fuel engine?

    <p>Between the carburetor and the air cleaner.</p> Signup and view all the answers

    What is the approximate pressure range at which CNG is stored in cylinders?

    <p>2000-3000 PSI</p> Signup and view all the answers

    What is the main role of the engine control unit (ECU)?

    <p>To monitor and adjust engine performance.</p> Signup and view all the answers

    Which material is NOT mentioned as a possible component of CNG storage cylinders?

    <p>Carbon fiber</p> Signup and view all the answers

    Which of the following is NOT a subsystem of the ECU?

    <p>A Fuel Pump.</p> Signup and view all the answers

    What is the maximum percentage an LPG fuel tank should be filled to?

    <p>80%</p> Signup and view all the answers

    What should always be used when filling a fuel tank?

    <p>A vapor return line</p> Signup and view all the answers

    What type of sensors are used to monitor temperature in a CNG engine?

    <p>Low-voltage temperature sensors.</p> Signup and view all the answers

    What material are the fuel lines made of?

    <p>Stainless steel</p> Signup and view all the answers

    What is the recommended action to take with fuel tank valves when storing equipment?

    <p>Close both the vapor and liquid valves</p> Signup and view all the answers

    What is the approximate pressure at which the gas enters the first stage of the fuel pressure regulator?

    <p>2,000 to 3,000 PSI</p> Signup and view all the answers

    What is a key difference between fuel delivery in gasoline and compressed gas engines?

    <p>Gasoline is a liquid when it reaches the carburetor, gas is vapor.</p> Signup and view all the answers

    What is the approximate gas pressure after the second stage of regulation for a non-fuel injected engine?

    <p>2.5 ounces PSI</p> Signup and view all the answers

    Why does a compressed-gas system not require a fuel pump?

    <p>The gas has built in pressure.</p> Signup and view all the answers

    Why should extra precaution be taken when filling an LPG fuel tank?

    <p>Some gas may escape during the filling process</p> Signup and view all the answers

    What is the purpose of a fuel lockoff valve in a compressed gas system?

    <p>To allow the fuel flow only when starting or running.</p> Signup and view all the answers

    What is the approximate pressure of the gas before entering a fuel metering block in a fuel injected engine?

    <p>130 PSI</p> Signup and view all the answers

    Which of these is a potential hazard associated with LPG vapors?

    <p>They are heavier than air and settle in low areas.</p> Signup and view all the answers

    What is adjusted due to the higher octane rating of CNG compared to gasoline?

    <p>Engine timing</p> Signup and view all the answers

    How often should CNG storage tanks be tested for corrosion and cracks?

    <p>Every 3 to 5 years</p> Signup and view all the answers

    Where should you be when filling storage tanks and equipment with CNG?

    <p>Outdoors</p> Signup and view all the answers

    What is the primary reason for painting fuel storage tanks?

    <p>To prevent rust</p> Signup and view all the answers

    What is a significant challenge when working with LPG and CNG fuel systems?

    <p>Dealing with high pressure</p> Signup and view all the answers

    What is the typical duration of objective instruction at the introductory level of basic principles and practices?

    <p>3 to 5 hours</p> Signup and view all the answers

    Which organization oversees the certification program for technicians servicing CNG and LPG systems on light and medium-duty trucks?

    <p>NATEF</p> Signup and view all the answers

    In the context of alternative fuel vehicles, what does 'bi-fuel' refer to?

    <p>An engine capable of operating on either gasoline or compressed gas.</p> Signup and view all the answers

    What does a 'converter' do in a compressed gas system?

    <p>It reduces pressure and vaporizes fuel to a dry gas.</p> Signup and view all the answers

    What is the first step in the CETP dual-certification process?

    <p>Written assessment</p> Signup and view all the answers

    Which organization has developed training materials for propane carburetion installation?

    <p>NPGA</p> Signup and view all the answers

    In the context of a compressed-gas system, what is the primary function of a 'lock-off valve'?

    <p>To control the flow of fuel.</p> Signup and view all the answers

    What does 'lean-burn' refer to in the context of fuel systems?

    <p>A system that uses more air than theoretically needed.</p> Signup and view all the answers

    Study Notes

    Operation and Service of LP and Natural Gas Fuel Systems

    • Natural gas and alternative fuels (like LPG and CNG) are gaining interest due to environmental and economic concerns.
    • Clean-burning LP gas and natural gas engines are used in various applications, including forklifts.
    • Alternative fuels are often cheaper, have higher octane ratings, and extend engine life.
    • Implementation of Clean Air Act led to the elimination of leaded gasoline.
    • Engines using compressed natural gas (CNG) or liquefied petroleum gas (LPG) often require modifications.

    Characteristics of Selected Alternative Fuels

    • Compressed Natural Gas (CNG): Primarily methane (CH4). 90% methane and 10% other gases. Source: underground reserves. Energy per gallon: 114,000 BTU. Power factor: 1.00. Form: vapor.
    • 15% Ethanol (E85): Denatured alcohol and gasoline. Source: corn or other grains. Energy per gallon: 80,000 btu.
    • 85% Gasoline/15% Ethanol (E85): Contains a mixture of gasoline and ethanol. Forms: liquid.
    • 85% Gasoline/15% Methanol (M85): A mixture of gasoline and methanol.
    • Liquefied Petroleum Gas (LPG): Propane (C3H8) and butane. Source: refining or natural gas. Energy per gallon: 84,000–91,000 BTU. Power factor: 1.38. Form: liquid.
    • Fuel Components/Chemical formula: Includes CH4, C3H8 etc
    • Different fuels have varying characteristics: octane ratings, energy content, etc.

    Advantages of Using LP-Gas and CNG Fuels

    • Spark-ignition engines can use these fuels after modifications.
    • Lower fuel costs than gasoline in some regions.
    • Higher octane ratings than gasoline.
    • Reduced harmful exhaust gases in many cases.
    • Prolong engine life; fewer carbon deposits.
    • Increase the interval between oil changes.

    Components of EFI Compressed Gas Fuel Systems

    • EFI systems are used in applications requiring variable engine speed (trucks and tractors).
    • Systems minimize fuel consumption through electronic technology.
    • Bi-fuel systems use two solenoid valves to switch between gasoline and compressed gases
    • Air-fuel mixer mounted between carburetor and air cleaner.

    Natural Gas Fuel System Specifics

    • CNG is a clean-burning, less expensive alternative fuel (primarily methane).
    • CNG is a naturally occurring gas and stored in cylinders under high pressure (2000-3000PSI).
    • Fuel systems involve fuel storage cylinders, pressure relief valves, and a pressure regulator.
    • Precise timing adjustments are required for CNG fuel systems due to its higher octane rating.

    Safety Practices for Handling and Storing LPG or CNG

    • Safety procedures must be followed carefully when handling and storing LPG and CNG.
    • Fuel tanks should not be filled completely; space must be left for expansion.
    • Vapor can ignite and cause fire hazards, so proper ventilation is necessary.
    • Only trained service technicians should service or repair CNG/LPG systems

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    Description

    This quiz covers the operation and service of LP and natural gas fuel systems, focusing on their environmental benefits and applications in various engines, including forklifts. It highlights the characteristics of alternative fuels like CNG and E85, discussing their energy content and benefits compared to traditional fuels.

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