When water-cooled condensers are used for distillation or for refluxing a liquid, the water?

Water condenser is used if bp of the liquid is 130 C or below 130 C. If bp is above 130 then cooling by air is adequate. So an air condenser is used. If a water condenser is used for a very high boiling liquid then there is a danger of cracking / breaking of condenser. For example, if bp of a liquid is 180 C than the temperature of the vapours will be obviously around 180. Then some portion of glass will be at 180 C temperature and water will be around 20 /25 C. There will be uneven temperature in the glassware and will break / crack. Air around air condenser will be at a higher temperature than water so difference of temperature will be less. Thus the arrangement will be safer. Water is allowed to get in from the lower inlet and is made to come out from the upper outlet. So that all the time inner pipe of the condenser remain surrounded by water. If it is other way round then water will be at the lower end and may not surround all the length of inner pipe. Water will quickly leave ...  more