 When more than three ports are included, they generally require more than one diaphragm seat; however, special dual actuators can handle more ports with one membrane.For high purity applications, the design of the basic weir-style diaphragm valve seal presents a number of issues for process engineers working in the biotechnology and pharmaceutical industry.In typical configurations, a weir in the valve body rises in a fluid path and when the valve is closed, the diaphragm meets the weir to shut off the flow.