Anaesthetic gas scavenging system (AGSS) terminal unit

ISO 9170-2:2008 sorts AGSS terminal units into two types by whether the power device of the disposal system is upstream or downstream of the terminal unit. ISO 9170-1:2017, for compressed medical gas and vacuum terminal units, leaves AGSS terminal units to Part 2, and ISO 7396-2 requires the avoidance of cross connections between AGSS disposal systems and medical gas or vacuum pipelines.

In HTM 02-01 (2026), the NHS England guidance, AGSS pipework ends in the patient area in a fully adjustable, gas-specific terminal unit to BS EN ISO 9170-2 (12.9). More than one AGS terminal unit may be installed in an operating or anaesthetic room, but only one per room is in use at a time; the plant should be sized for two terminal units per operating suite, and an AGSS designed to serve at most six (12.25, 12.29, 12.30). Terminal units should be checked for correct mechanical operation and for their check valve, and annual recommissioning includes stripping, cleaning and resetting them (19.171, 19.172, 19.174).

In the Ultra Controlo ULTRASEG active AGSS, the anaesthetic breathing circuit is connected through a receiver unit to the terminal unit, which has an adjustable orifice to set the flow for high-flow or low-flow systems.