Definition of Aniline Point, Pour point and Cloud point,Otane number,Cetane number

Aniline Point:

The  lowest  temperature  at  which  the  fuel  is
completely  miscible   with  an  equivalent
amount of aniline.

Pour point and Cloud point:

If an oil is cooled, it will start solidifying at some 

temperature.  This  temperature  is  called  cloud 

point.

This clouding or haziness of the oil interferes with 

its flow.

The  pour  point  is  that  temperature  just  above 

which the oil sample will  not flow under certain 

prescribed condition. This temperature is largely 

determined by the wax content of the oil.

Octane number:

In  any  unknown  gasoline  performance,  isooctane’s  percentage  by  volume  is  taken  as  the 

octane number in a mixture of iso-octane and nheptane. 

Cetane number:

In  any  unknown  diesel  fuel  performance, 

cetane’s  percentage  by  volume  is  taken  as  the 

cetane number in a mixture of cetane  (n-C16H34)

and alpha-methyl nepthalene (C10H7CH3)

Cetane number  is an inverse function of a fuel's 

ignition delay, and the time period between the 

start  of  injection  and  the  first  identifiable 

pressure increase during combustion of the fuel. 

In a particular diesel engine, higher cetane fuels 

will  have  shorter  ignition  delay  periods  than 

lower  Cetane  fuels.  Cetane  numbers  are  only 

used for the relatively light distillate diesel oils.