Some heat is generated in Cylinder when Engine is in working condition.To keep Cylinder in cool condition Air or Water is used as Cooling Media.When the Engine is cooled by circulating water around Cylinder then the Engine is called 'Water Cooled Engine".
If the Engine is kept idle (without use) for long time there is a possibility of freezing of water.This mostly happens in Winter.
The water may freeze and expands leading to fracture in Water Jackets,Water Circulating Pipe or Radiator.To lower the freezing Temperature,certain mixture are added to water.This mixture are known as "Antifreezers".
To avoid the wastage of Antifreezers due to Evaporation,its boiling point should be as high as of water.
The important qualities of ideal Antifreezers.
01)It should easily dissolve in water.
02)It should be reasonably cheap.
03)Should not deposit any foreign matters in the Water Jackets,Pipes and cause no harmful effects to any part of Cooling System.
No single Antifreezers satisfies all these requirements.The material in common use are Glycerine,Ethylene Glycol,Propylene,Alcohol and mixture of Glycerine and Alcohol.If Alcohol is used,frequent checking with a Hydrometer is required.Glycerin,Ehtylene and Propylene Glycol though have high initial cost,prove cheap in long run,provided proper care is taken against leakage,because there mixture do not Evaporate.