When the sample is heat-sensitive, oxidizes, or contains solvents that must be removed at low temperature: reducing the pressure allows evaporation to occur at much lower temperatures without damaging the material. Conventional heat drying is simpler and faster for robust materials.

A vacuum pump suited to the solvent (a chemical pump for corrosive vapors) and, where applicable, a cold trap. It is best to define this together with the equipment to ensure compatible ranges and connections.

Only in vacuum ovens designed for that purpose, with an interior and controls prepared for potentially explosive atmospheres. This is a safety requirement that must be specified at the time of purchase.

The oven is the general-purpose thermal unit; the drying oven is optimized to remove moisture with a high air exchange rate, and the vacuum oven adds reduced pressure. The choice depends on the material and the process.