# What is a method of insulation that can completely eliminate heat loss by conduction?

Apr 4, 2016

Vacuum jacketing?

#### Explanation:

The vacuum or Dewar flask is a hollow, double-jacketed glass tube, whose interior has been pumped out to very high vacuum. Conduction can occur thru the lip of the flask (Dewar flasks can have frosty mouths) but conduction cannot occur across the vacuum of the glass walls. Sometimes, your Dewar $\text{goes soft}$, i.e. the vacuum is lost, and its insulating properties are lost.

A broken Dewar or a broken thermos flask (the which are also Dewar flasks) are quite dangerous, because the glass shards are sharp and can get everywhere. This is why all such Dewar flasks are taped or contained within a hard plastic shell.