Microwave Digestion Vessel is used for quick heating of materials, compounds such as water and other polar liquids that absorb microwave energy rapidly. A sample placed inside a microwave digestion vessel with a polar liquid or ionic solution usually acid is subjected to rapid heating and in the case of a sealed vessel, elevated pressures, causing the sample to digest or dissolve in a short time. Microwave sample preparation system is operated under full microprocessor control with constant monitoring of the door safety interlocks, pressure and if required temperature, within the digestion vessel. An exhaust tube to vent fumes is permanently connected to an adjacent fume cupboard. A microwave oven works by passing microwave radiation, usually at a frequency of 2.45 GHz through the material. Materials absorb energy from the microwaves in a process called dielectric heating. Many molecules such as those of water are electric dipoles, meaning that they have a positive charge at one end and a negative charge at the other and therefore rotate as they try to align themselves with the alternating electric field induced by the microwaves. This molecular movement creates heat as the rotating molecules hit other molecules and put them into motion.