Properties and Safety Flashcards
7 cards from real CNG practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Properties and Safety flashcards as text
What is the approximate energy content of CNG compared to gasoline on a volume basis?
Answer: One gasoline gallon equivalent (GGE) of CNG contains about the same energy as one gallon of gasoline
One Gasoline Gallon Equivalent (GGE) of CNG is defined to contain approximately the same energy (about 114,000 BTU) as one gallon of gasoline.
CNG cylinders must undergo periodic requalification testing. What is the standard requalification interval for most CNG cylinders?
Answer: Every 10 years or per manufacturer specification
Most CNG cylinders require requalification every 5 years or per the manufacturer's specification, and cylinders typically have a service life of 15-20 years.
What type of ventilation is required for enclosed spaces where CNG vehicles are parked or serviced?
Answer: High-level or ceiling ventilation to prevent methane accumulation
Because methane is lighter than air and rises, ventilation for CNG vehicle areas must include high-level or ceiling-mounted exhaust to prevent dangerous gas accumulation.
What does 'CNG equivalent' mean when comparing fuel economy ratings?
Answer: Fuel economy expressed in miles per gasoline gallon equivalent (mpgge)
CNG fuel economy is expressed in miles per gasoline gallon equivalent (mpgge) to allow standardized comparison with gasoline vehicles.
Which NFPA standard specifically covers compressed natural gas vehicular fuel systems?
Answer: NFPA 52
NFPA 52 (Vehicular Gaseous Fuel Systems Code) covers CNG and other gaseous fuels used in vehicle fuel systems, including installation and safety requirements.
When should a CNG cylinder be immediately removed from service?
Answer: If it has been involved in a fire or shows signs of heat damage
A CNG cylinder exposed to fire or showing signs of heat damage must be immediately removed from service because heat can compromise the structural integrity of the cylinder material.
What is the primary hazard of CNG in an enclosed space without adequate ventilation?
Answer: Asphyxiation from oxygen displacement and explosion risk
In an enclosed space, accumulating methane can displace oxygen causing asphyxiation, and once in the flammable range (5-15%), can create an explosion hazard.