this invention comprises a method of sealing a valve unit to a reservoir by vibrating to cause melting and reshaping . also the invention comprises a valve unit 1 and reservoir 2 assembly including a valve unit 1 and at least part of the reservoir 2 having members defining a valve bore 5 , the valve bore 5 receiving the valve unit 1 wherein the valve unit 1 is meltedly attached to the members defining the valve bore 5 .