A liquid separator includes a housing, a separation chamber disposed within the housing, a drain, an inlet channel, a swirler disposed within the inlet channel, and an outlet channel. The drain has a drain passageway for draining liquid from the separation chamber. The inlet channel is configured to communicate the fluid stream from a first inlet end to a second inlet end disposed within the housing and proximate the separation chamber. The outlet channel is configured to communicate the fluid stream from a first outlet end positioned proximate the second inlet end, to a second outlet end remote from the separation chamber. The drain passageway has an inner diameter sized such that the interaction between the surface tension of the liquid and the inner passageway causes some liquid to be retained in the drain passageway, to form a low pressure gas seal of the drain passageway.