Degassers are used to remove small amounts of entrained gas, such as methane, hydrogen sulfide, and carbon dioxide, from drilling muds — as well as wastewater and other process fluids. Degassers primarily function by one of two basic operating principles: negative pressure (vacuum) and atmospheric degassing. In both cases, fluid is fed through a series of baffles or dispersion plates whereas fluid surface area is increased, allowing the entrained gas to separate either naturally or by the assistance of a vacuum pump.

Degassers used in the oil and gas industry are classified as a piece of solids control equipment. Degassers condition drilling fluid — mud, by removing entrained gases that would otherwise disrupt the hydrostatic head due to the compressive nature of gaseous fluids. Degassers process mud flowing downstream from mud/gas separators, shale shakers, and mud conditioners. Other solids control equipment placed downstream from a degasser include hydrocyclones and centrifuges.

Image credit: GN Solids Control