Abstract: A flow tube for a bidirectional flow meter includes a first flow chamber for generating a periodic pressure fluctuation whose frequency varies in dependence on the flow rate of fluid through the meter in a first direction. The flow tube also includes a second flow chamber for generating a periodic pressure fluctuation whose frequency varies in dependence on the flow rate of fluid through the meter in a second direction, opposite to the first direction. The first and second flow chambers are connected in series between an inlet port and an outlet port.

Abstract: A flow tube for a bidirectional flow meter comprises a first means (for example in the form of a first flow chamber) for generating a periodic pressure fluctuation whose frequency varies in dependence on the flow rate of fluid through the meter in a first direction; and a second means (for example in the form of a second flow chamber) for generating a periodic pressure fluctuation whose frequency varies in dependence on the flow rate of fluid through the meter in a second direction, opposite to the first direction; wherein said first and second generating means are connected in series between an inlet port and an outlet port.