An exchange device includes a plate having a top surface, a bottom surface, a plurality of openings extending between the top and bottom surfaces. The top surface receives a liquid which flows in a flow direction over the top surface. A plurality of valves is disposed over the openings. Each valve includes a round lid coupled to the first, second, and third legs. The first leg is upstream of the second and third legs relative to the flow direction. The first leg has a width that is greater than the width of the second and third legs. In particular, a ratio of the width of the first leg to the width of the second leg is in a range of 1.6:1 to 2.6:1.