Octane RequirementUnleaded regular automotive gasoline shall meet the Motor Octane Number (MON), Research Octane Number (RON) and/or Anti- Knock Index (AKI) limits described in the specification listed for each country or the in-country requirements when applicable. We have detail understanding of AKI requirements and blending of oxygenates into gasoline to meet oxygenated fuel requirements in the country and as per the vehicle requirements. The antiknock index (AKI) is the arithmetic average of the Research octane number (RON) and Motor octane number (MON):
AKI = (RON + MON) / 2
Unleaded fuel having an antiknock index of at least 87 should also have a minimum Motor octane number of 82 in order to adequately protect those vehicles that are sensitive to Motor octane quality.
Volatile mixture of liquid hydrocarbons, generally containing small amounts of additives, suitable for use as a fuel in spark-ignition, internal combustion engines.
The ability to absorb small quantities of water without creating a separate phase in the fuel. Improved water tolerance is the ability to absorb larger quantities of water without phase separation.
To determine when a fuel contains a substantial amount of an oxygenate, a gasoline-oxygenate blend is defined as a fuel that contains more than 0.35 % by mass oxygen, or more than 0.15 % by mass oxygen if methanol is the only oxygenate. The definitions in this section do not apply to fuels that contain an oxygenate as the primary component; for example, fuel methanol (M85). The finished fuel shall also be free of any adulterant or contaminant that can render the fuel unacceptable for its commonly used applications.
Vapor-Liquid Ratio must be between 8 to 1 and 75 to 1. For this specification, it is conducted at a ratio of 20 to 1. It may be used for gasoline and gasoline-oxygenate blends.
The fuel-air mixture in the cylinder of a spark-ignition engine will, under certain conditions, auto-ignite in localized areas ahead of the flame front that is progressing from the spark. This is engine spark knock which can cause a ping that may be audible to the customer.