Vapour Immersion Unit: which has two solvent-filled sumps (the boil sump and the cold sump which is filled with clean, distilled condensate solvent and is often used for rinsing). An ultrasonic-equipped degreaser is a version of a vapor immersion type degreaser.
Vapor Spray Unit: in which the solvent is boiled in the very bottom of a one-sump degreaser. There is a perforated metal stand just above the boiling solvent. A metal basket filled with dirty parts is usually placed on this stand. The basket or parts are not immersed in the solvent. Instead, the vapor made by the boiling solvent encompasses the parts completely and removes the oils and soils. The oils and soils, now diluted into the condensing liquid, will drip back into the boiling solvent below. There is a manual spray wand, which is sprayed under the cooling coils, directly on the hard-to-remove soil.