Abstract: A trapping device for trapping foreign liquids having a specific gravity greater than that of a supply liquid comprises a settling chamber defined primarily by a tubular side wall and two end pieces and inlet and outlet chambers in the settling chamber and adjacent to an upper one of the end pieces. An inlet and an outlet lead to and from the inlet and outlet chambers, which are separated by an imperforate wall. The imperforate wall has a pair of wing means diverging radially outwardly. Foraminous wall means are arranged so that fluid passing through the chambers from the inlet to the outlet passes through the foraminous wall means.