Ultrasonic flow meters use sound frequencies to determine flow rates. They can be either Doppler effect meters or Time-of-Flight meters. Doppler meters measure the frequency shifts caused by liquid flow. The frequency shift is proportional to the liquid's velocity. Time of flight meters use the speed of the signal traveling between two transducers that increases or decreases with the direction of transmission and the velocity of the liquid being measured. They do not work well with liquids with suspended solids or air gaps.
The basis of good flowmeter selection is a clear understanding of the requirements of the particular application. Measuring the flow of liquids is a critical need in many industrial plants. In some operations, the ability to conduct accurate flow measurements is so important that it can make the difference between making a profit and taking a loss. In other cases, inaccurate flow measurements or failure to take measurements can cause serious (or even disastrous) results.
Ultrasonic flow meters use sound frequencies to determine flow rates. They can be either Doppler effect meters or Time-of-Flight meters. Doppler meters measure the frequency shifts caused by liquid flow. The frequency shift is proportional to the liquid's velocity. Time of flight meters use the speed of the signal traveling between two transducers that increases or decreases with the direction of transmission and the velocity of the liquid being measured. They do not work well with liquids with suspended solids or air gaps.
The basis of good flowmeter selection is a clear understanding of the requirements of the particular application. Measuring the flow of liquids is a critical need in many industrial plants. In some operations, the ability to conduct accurate flow measurements is so important that it can make the difference between making a profit and taking a loss. In other cases, inaccurate flow measurements or failure to take measurements can cause serious (or even disastrous) results.
Important parameters to consider when specifying ultrasonic flow meters include flow rate range, operating pressure, fluid temperature, and accuracy. The flow rate range is the flow in distance/time. The operating pressure is the maximum head pressure of the process media the meter can withstand. The maximum temperature of the media that can be monitored is usually dependent on construction and liner materials. Accuracy is measured in () %. Pipe diameter is also important to consider, especially when specifying specific mounting options.
Mounting options for ultrasonic flow meters include insertion types, in-line flanged, in-line threaded, and in-line clamp. Insertion flow meters are inserted perpendicular to flow path. They usually require a threaded hole in the process pipe or other means of access. In-line flanged flow meters are inserted parallel to the flow path, usually inserted between two pieces of existing flanged process pipes. In-line threaded flow meters are inserted parallel to the flow path, and threaded into two existing process pipes. NPT is the most common thread type. In-line clamp flow meters are inserted parallel to the flow path, and clamped between two existing process pipes.
Ultrasonic flow meter output types include analog voltage, analog current, frequency or pulse, and switch. Interface options for ultrasonic flow meters include serial and parallel interfaces. User interface options available on ultrasonic flow meters include analog front panels, digital front panels, and computer controls.
