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 fluid flow meter, including a fluid flow path and rotor. The rotor has at least one blade positioned in the fluid flow path. A ring is positioned upstream from, and adjacent to the rotor. The ring is adapted to condition the flow at the leading edge of the rotor blade over a range of operating conditions.

Abstract: A positive displacement fluid flow meter comprises a chamber having a fluid inlet and a fluid outlet. A rotor is displaceable within the chamber, rotation of the rotor being related to the volume of fluid passing through the chamber. The chamber has a surface proximate which an end surface of the rotor passes, the chamber surface and/or the rotor end surface having at least one recess to retain at least a portion of debris carried by the metered fluid. The recess is preferably formed so as not to provide fluid, communication, from the inlet to the outlet across the rotor end surface. A lid closes an end of the chamber which in use is subject to the pressure of fluid within the chamber. The lid is engaged at its periphery to a wall of the chamber, and is preferably flexible adjacent its periphery to reduce the transmission of bending stresses between the periphery of the lid and the remainder thereof.

Abstract: The present invention relates to a fluid flow meter, comprising: means for defining a fluid flow path; a rotor, with at least one blade, positioned in said fluid flow path; and a ring positioned upstream from, and adjacent to, said rotor; wherein the ring is adapted to conditions the flow at the leading edge of the rotor blade over a range of operating conditions. By providing a ring the accuracy and flow measuring range may be improved.

Abstract: A bi-directional flowmeter comprises a first fluidic oscillator device arranged to measure the flow of fluid in a first direction and a second fluidic oscillator device arranged to measure the flow of fluid in a second direction opposite to the first direction and in which the two oscillators devices are connected together in series between an inlet port and an outlet port of the flowmeter between which the fluid to be measured can flow.

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.

Abstract: A positive displacement fluid flow meter comprises a chamber having a fluid inlet and a fluid outlet. A rotor is displaceable within the chamber, rotation of the rotor being related to the volume of fluid passing through the chamber. The chamber has a surface proximate which an end surface of the rotor passes, the chamber surface and/or the rotor end surface having at least one recess to retain at least a portion of debris carried by the metered fluid. The recess is preferably formed so as not to provide fluid, communication, from the inlet to the outlet across the rotor end surface. A lid closes an end of the chamber which in use is subject to the pressure of fluid within the chamber. The lid is engaged at its periphery to a wall of the chamber, and is preferably flexible adjacent its periphery to reduce the transmission of bending stresses between the periphery of the lid and the remainder thereof.

Abstract: A bi-directional flowmeter comprises a first fluidic oscillator device arranged to measure the flow of fluid in a first direction and a second fluidic oscillator device arranged to measure the flow of fluid in a second direction opposite to the first direction and in which the two oscillators devices are connected together in series between an inlet port and an outlet port of the flowmeter between which the fluid to be measured can flow.

Abstract: An indexing mechanism comprising a body (10) mounted so as to be rotatble about an axis; means (3) for rotating said body about said axis; first cam means (9, 10) for displacing said body along said axis away from an axial rest position during rotation of said body in a first direction; biassing means (11) for restoring the body to its axial rest position on completion of a rotation or a predetermined portion thereof of the body; means (8a) for detecting the axial movement of the body when it is being restored to its axial rest position; and second cam means (2, 9) permitting said body to be rotated in a second direction opposite the first direction.

Abstract: An electromagnetic flow meter is configured as an insert for insertion into an in-situ housing connected in a flow line. This can enable a body previously installed for use with an insert of a mechanical flow meter to be adapted for use with an insert of an electromagnetic flow meter without having to disconnect the body from a mains supply.