Plungers and plunger assemblies for a diaphragm-sealed valve are provided. Each plunger is adapted to be received in a passage of the valve body and includes a base member and an upper member having a transversal play in this passage with respect to the base member. A resilient middle element is provided between the upper and base member. The base member is connected to a plunger actuating mechanism within the valve body. The upper member may therefore be self-aligning within the passage.