1. A space which is designed to isolate an air conditioned space from another space to which it is connected.
2. In a pump or piping system, the stoppage of flow resulting from the presence of trapped air.and egress from one room to another while permitting
minimal air movement between rooms.
3. An enclosure with control doors between two rooms that permits the ingress and egress from one room to another while permitting minimal air movement between rooms.