Question

differentiate between CNG and LPG

Answer 1

CNG: compressed natural gas.it is a fuel which can be used in place of petrol.it is safer than other fuels because it is lighter than air.

LPG: liquified petroleum gas.it is also referred to butane or propane. it has a higher calorific value.

hope this helps U

Answer 2

CNG : Compressed Natural Gas or CNG is stored on the vehicle in high-pressure tanks - 20 to 25 MPa (200 to 250 bar, or 3,000 to 3,600 psi).  Natural gas consists mostly of methane and is drawn from gas wells or in conjunction with crude oil production.  As delivered through the pipeline system, it also contains hydrocarbons such as ethane and propane as well as other gases such as nitrogen, helium, carbon dioxide, sulphur compounds, and water vapour.  A sulphur-based odourant is normally added to CNG to facilitate leak detection.  Natural gas is lighter than air and thus will normally dissipate in the case of a leak, giving it a significant safety advantage over gasoline or LPG.  

LPG : Liquefied Petroleum Gas or LPG (also called Autogas) consists mainly of propane, propylene, butane, and butylene in various mixtures.  It is produced as a by-product of natural gas processing and petroleum refining.  The components of LPG are gases at normal temperatures and pressures.  One challenge with LPG is that it can vary widely in composition, leading to variable engine performance and cold starting performance.  At normal temperatures and pressures, LPG will evaporate. Because of this, LPG is stored in pressurised steel bottles.  Unlike natural gas, LPG is heavier than air, and thus will flow along floors and tend to settle in low spots, such as basements.  Such accumulations can cause explosion hazards, and are the reason that LPG fuelled vehicles are prohibited from indoor parkades in many jurisdictions.