Gas throttling is reduction of pressure in a gas flow forced through a throttle – local hydrodynamic resistance point (orifice choke, valve, tap, check), accompanied by temperature change.

Gas throttling is used for liquefying and deep refrigeration of gases. The latter is performed in low temperature separation devices during gas treatment before long-distance transportation. In addition, gas throttling is used in pipeline gas transmission for gas flow rate and pressure regulation.

Throttling can cause frosting of locking, regulating and metering devices, as well as forming of gas hydrates in pipelines. As a result of gas throttling the gas temperature in gas trunklines can decrease below the ambient temperature.