CNG Quiz Flashcards
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Questions and Answers

How often does a CNG cylinder inspection need to be done?

CNG cylinder inspections are required every three years, or 36,000 miles, or after any fire or accident.

What is the major constituent in natural gas?

Methane

Which fuel has the lowest carbon content?

Natural gas

What is the chemical composition of methane?

<p>CH4</p> Signup and view all the answers

Natural gas is ____.

<p>lighter than air</p> Signup and view all the answers

Natural gas has which of the following characteristics?

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

What is the ignition temperature of natural gas?

<p>900 degrees to 1080 degrees Fahrenheit</p> Signup and view all the answers

For natural gas, the lower the flammability limit is ____% and the upper flammability limit is ___%.

<p>5, 15</p> Signup and view all the answers

What are the human health hazards that must be considered when working on CNG vehicle?

<p>High pressure, fire, and asphyxiation</p> Signup and view all the answers

What is the maximum fill pressure of a 3,600 PSI cylinder?

<p>4,500 psi</p> Signup and view all the answers

What is the minimum burst pressure of a high pressure fuel line?

<p>20,000 PSI</p> Signup and view all the answers

What is the minimum burst pressure of a 3600 PSI CNG cylinder?

<p>8100 PSI</p> Signup and view all the answers

These are true statements about compressed natural gas.

<p>As temperature decreases, pressure decreases. As temperature increases, pressure increases.</p> Signup and view all the answers

The rated service pressure of CNG cylinders is measured at what temperature?

<p>70 degrees Fahrenheit</p> Signup and view all the answers

What standards address CNG cylinder design in manufacturing?

<p>ANSI NGV 2 and FM VSS304</p> Signup and view all the answers

The primary installation code for CNG cylinders and fuel system components is ____.

<p>NFPA 52</p> Signup and view all the answers

Why is NFPA 52 important?

<p>It helps the CNG fuel system inspector identify unsafe installation practices.</p> Signup and view all the answers

When inspecting CNG cylinders, the primary inspection guidance document is ____.

<p>cylinder manufacturers guidelines; the second is CGA C 6.4</p> Signup and view all the answers

What is NGV2 #1?

<p>All metal cylinder made of steel or aluminum</p> Signup and view all the answers

What is NVG2 #2?

<p>A cylinder made of steel or aluminum with a hoop wrapped overwrap</p> Signup and view all the answers

What is NVG2 #3?

<p>A cylinder made of thin steel or aluminum liner with a fully wound overwrap</p> Signup and view all the answers

What is NVG2 #4?

<p>A cylinder with a plastic liner in a fully wound overwrap</p> Signup and view all the answers

What are the primary causes of CNG cylinder failure?

<p>Undetected external damage causes ruptures most often during fueling.</p> Signup and view all the answers

What does the CNG fuel receptacle do?

<p>Allow CNG to flow into the vehicle, is equipped with a one-way check valve.</p> Signup and view all the answers

Which CNG fuel system component prevents gas from flowing to the engine when the key is on, but the engine is not running?

<p>Fuel shutoff solenoid valve</p> Signup and view all the answers

Type 3 CNG cylinders are made of ____.

<p>metal liner in a fiber and resin composite outer wrap</p> Signup and view all the answers

Type 4 CNG cylinders are made of ____.

<p>non-metallic liner in a fiber and a resin composite material</p> Signup and view all the answers

The most significant safety hazard with CNG cylinders is ____.

<p>rupture during fueling due to undetected damage</p> Signup and view all the answers

The CNG fuel receptacle contains a check valve designed to ____.

<p>prevent CNG fuel from flowing back out of the receptacle</p> Signup and view all the answers

The O ring inside the fuel receptacle provides ____.

<p>a seal between the nozzle and the receptacle</p> Signup and view all the answers

The secondary check valve is ____.

<p>installed to prevent CNG from flowing back to the receptacle</p> Signup and view all the answers

The defueling system is ____.

<p>required by NFPA 52, should only be used by properly trained personnel, should be leak checked during the fuel system inspection.</p> Signup and view all the answers

What is ANSI NGV1?

<p>compressed natural gas vehicle fueling connection devices, receptacles, and nozzles.</p> Signup and view all the answers

What is ANSI NGV2?

<p>compressed natural gas vehicle fuel containers, cylinders, and mounting.</p> Signup and view all the answers

What is DOT FMVSS 304?

<p>Compressed natural gas integrity.</p> Signup and view all the answers

What is ANSI PRD?

<p>pressure relief devices for natural gas vehicle fuel containers.</p> Signup and view all the answers

What is ANSINGV 3.1?

<p>guidance for compressed natural gas powered vehicle and all other components.</p> Signup and view all the answers

What are the three types of codes and standards?

<p>manufacturing standards, installation code, inspection standards.</p> Signup and view all the answers

What is the National Fire Protection Association NFPA 52 vehicular natural gas fuel system code?

<p>primary document for installation of cylinders and fuel system components.</p> Signup and view all the answers

What is ANSI NGV 6.1?

<p>compressed natural gas fuel storage and delivery systems for road vehicles.</p> Signup and view all the answers

What are the codes and standards documents for inspectors?

<p>NFPA 52, ANSI NGV 6.1, CGA C 6.4, Cylinder manufacturers inspection guidelines.</p> Signup and view all the answers

What is the primary document to be used for cylinder manufacturers inspection guidelines?

<p>CGA C6.4 is the second.</p> Signup and view all the answers

What is a fuel receptacle?

<p>where CNG enters the fuel system equipped with one-way flow check valve.</p> Signup and view all the answers

What is a secondary check valve?

<p>redundant valve to prevent gas from returning to the receptacle.</p> Signup and view all the answers

What is a defueling system?

<p>allows gas to be removed from the high pressure fuel system for service or repair.</p> Signup and view all the answers

What do fittings like O Ring Face Seal and Double Ferrule do?

<p>connect sections of high pressure tubing to each other and/or components.</p> Signup and view all the answers

What are cylinder valves?

<p>manual, electric, and electro-mechanical open and close the flow of fuel into the storage cylinders.</p> Signup and view all the answers

What are PRDs and vent lines?

<p>must be thermally activated.</p> Signup and view all the answers

What are fuel system isolation valves?

<p>either a manual or solenoid valve that allows for the shut off of gas to the engine in an emergency.</p> Signup and view all the answers

What is fuel system isolation valves operation?

<p>the automatic shutoff valve shall not be opened unless the engine is rotating or in a startup sequence.</p> Signup and view all the answers

What does a high pressure coalescing filter do?

<p>removes liquid or aerosol oil, water, and particulates from gas.</p> Signup and view all the answers

What is a fuel shutoff solenoid valve?

<p>prevents gas from flowing to the engine when the key is on, but the engine is not running.</p> Signup and view all the answers

What does a high pressure gauge do?

<p>displays pressure in the high pressure fuel system.</p> Signup and view all the answers

What is a high pressure transducer?

<p>transducer communicates pressure to control module and fuel gauge.</p> Signup and view all the answers

What does a pressure regulator do?

<p>reduces high pressure to engine operating pressure.</p> Signup and view all the answers

Type 1 CNG cylinders are made of what?

<p>all metal cylinder made of steel or aluminum, 100 percent of load taken by liner, zero percent of load taken by composite.</p> Signup and view all the answers

Type 2 CNG cylinders are made of what?

<p>a cylinder made of steel or aluminum with a hoop wrap overwrap, 55% of load taken by liner, 45% of load taken by composite.</p> Signup and view all the answers

Type 3 CNG cylinders are made of what?

<p>a cylinder made of thin steel or aluminum liner with a fully wound overwrap, 20% of load taken by liner, 80% of load taken by composite.</p> Signup and view all the answers

Type 4 CNG cylinders are made of what?

<p>a cylinder with a plastic liner in a fully wound overwrap, zero percent of the load taken by liner, 100% of load taken by composite.</p> Signup and view all the answers

What are the primary causes of CNG cylinder failure?

<p>virtually all CNG cylinder failures have resulted from external damage; undetected external damage causes ruptures most often during fueling.</p> Signup and view all the answers

What does the CNG fuel receptacle do?

<p>allows CNG to flow into the vehicle; it is equipped with a one-way check valve.</p> Signup and view all the answers

What is a fuel shutoff solenoid valve?

<p>prevents gas from flowing to the engine when the key is on but the engine is not running.</p> Signup and view all the answers

What do Type 1 CNG cylinders entail?

<p>all metal cylinder made of steel or aluminum with 100 percent of load taken by liner and zero percent by composite.</p> Signup and view all the answers

What do Type 2 CNG cylinders entail?

<p>a cylinder made of steel or aluminum with a hoop wrap overwrap; 55% load taken by liner, 45% by composite.</p> Signup and view all the answers

What do Type 3 CNG cylinders entail?

<p>a cylinder made of thin steel or aluminum liner with a fully wound overwrap; 20% load taken by liner, 80% by composite.</p> Signup and view all the answers

What do Type 4 CNG cylinders entail?

<p>a cylinder with a plastic liner in a fully wound overwrap; 0% load taken by liner, 100% by composite.</p> Signup and view all the answers

Study Notes

CNG Cylinders and Inspections

  • CNG cylinder inspections are mandatory every three years, every 36,000 miles, or after incidents like fires or accidents.
  • NFPA 52 is the primary installation code for CNG cylinders and fuel system components, aiding in identifying unsafe practices.

Natural Gas Composition and Characteristics

  • Major element of natural gas is methane, with a chemical formula of CH4.
  • Natural gas is lighter than air and is odorless.
  • It has the lowest carbon content compared to other fuels, making it more environmentally friendly.

Ignition and Flammability

  • Ignition temperature of natural gas ranges from 900°F to 1080°F.
  • Flammability limits: lower limit is 5%, upper limit is 15%.

Health Hazards of CNG

  • Significant hazards include high pressure, fire risks, and asphyxiation when handling CNG vehicles.

Cylinder Pressure Details

  • Maximum fill pressure for a 3,600 PSI CNG cylinder is 4,500 PSI.
  • CNG cylinders must withstand a minimum burst pressure of 8,100 PSI.

Cylinder Design Standards

  • CNG cylinder design must comply with ANSI NGV 2 and FM VSS304 standards.
  • Various types of cylinders (Type 1, Type 2, Type 3, Type 4) differ in materials and load capacities.

CNG Cylinder Failures

  • Primary cause of failures is undetected external damage, often leading to ruptures during fueling.

Fuel System Components

  • The CNG fuel receptacle includes a check valve to prevent backflow and requires an O-ring seal.
  • A fuel shutoff solenoid valve stops gas flow to the engine when the vehicle is on but not running.

CNG Defueling Systems

  • Requires trained personnel for operation and must be leak-checked during inspections.

Pressure Regulation

  • High-pressure coalescing filters remove contaminants from gas.
  • Pressure regulators reduce high pressure to suitable engine operating pressure.

Codes and Standards

  • Important standards include ANSI NGV 1 (fueling connections) and ANSI NGV 6.1 (storage and delivery systems).
  • Codes and standards documents are crucial for inspectors, including CGA C 6.4 and manufacturer guidelines.

Safety Measures

  • Secondary check valves are installed to prevent gas from reverting back into the receptacle.
  • Fuel system isolation valves allow for emergency gas shutoff to the engine.

Cylinder Types

  • Type 1: All metal (steel/aluminum) with all load on the liner.
  • Type 2: Steel/aluminum with hoop overwrap, with part of the load on the composite.
  • Type 3: Thin liner with complete overwrap, with a majority of the load on the composite.
  • Type 4: Plastic liner with full composite overwrap, with no load taken by the liner.

Maintenance and Inspection Guidelines

  • Follow cylinder manufacturers' guidelines for inspections, with CGA C 6.4 as the secondary document.
  • NFPA 52 details requirements for defueling systems and fuel system inspections to ensure safety.

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Test your knowledge on Compressed Natural Gas (CNG) with these flashcards. Learn about cylinder inspections, the chemical composition of methane, and the environmental impact of natural gas. Perfect for students and professionals in the energy sector.

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