Dual sensor vortex flowmeter

A method of measuring a flow rate of a fluid flow using a vortex flowmeter comprising:

• positioning a vortex shedder of the vortex flowmeter in the fluid flow;
• when the flow rate is less than a first threshold flow rate, performing a low flow mode measurement of the flow rate using an ultrasonic flow rate output produced by an ultrasonic sensor of the vortex flowmeter positioned downstream of the vortex shedder;
• when the flow rate is greater than a second threshold flow rate, which is greater than the first threshold flow rate, performing a high flow mode measurement of the flow rate using a bending moment flow rate output produced by a bending moment sensor of the vortex flowmeter positioned downstream of the vortex shedder;
• when the flow rate is between the first and second threshold flow rates, performing a medium flow mode measurement of the flow rate using the ultrasonic flow rate output and the bending moment flow rate output;
• comparing the ultrasonic flow rate output with the bending moment flow rate output;
• and
• detecting a condition of the fluid flow or a condition of a pipe containing the fluid flow based on the comparison wherein the condition is at least one of gas entrained in the fluid flow, cavitation in the fluid flow, a high vibration condition of the pipe, and an absence of liquid condition in the pipe.

A method of measuring a flow rate of a fluid flow using a vortex flowmeter comprising:

• positioning a vortex shedder of the vortex flowmeter in the fluid flow;
• when the flow rate is less than a first threshold flow rate, performing a low flow mode measurement of the flow rate using an ultrasonic flow rate output produced by an ultrasonic sensor of the vortex flowmeter positioned downstream of the vortex shedder;
• when the flow rate is greater than a second threshold flow rate, which is greater than the first threshold flow rate, performing a high flow mode measurement of the flow rate using a bending moment flow rate output produced by a bending moment sensor of the vortex flowmeter positioned downstream of the vortex shedder;
• when the flow rate is between the first and second threshold flow rates, performing a medium flow mode measurement of the flow rate using the ultrasonic flow rate output and the bending moment flow rate output;
• wherein the first threshold flow rate is less than 30 m3/h;
• and
• wherein the second threshold flow rate is greater than 80 m3/h.