An ultrasonic flow meter measures the velocity of a liquid using ultrasound to calculate volume flow. Ultrasound is the sound generated above the human hearing range. There are two types of ultrasonic flow meter: Transit Time, or Time of Flight, and Doppler. Both are available in a clamp-on meter configuration with transducers, which are used to detect and measure flow rate from the outside of the pipe. Transit Time flow meters use two transducers and usually work at a frequency of 1 to 2 MHz. A higher frequency is used for smaller pipe installations, hence the need for several different transducer sets. Doppler flow meters use a single transducer and operate between 500 KHz and 1 MHz.
It is very important to select the correct ultrasonic technology for each application. Doppler flow meters are best suited for the measurement of dirty liquids or liquids with entrained air. It is critical that particles in suspension or entrained air bubbles are present so that they can reflect the ultrasonic beam, which is how the flow meter functions. Transit Time ultrasonic flow meters are primarily used with clean liquids. The presence of solids or large quantities of air in these would attenuate the ultrasonic beam and weaken it to make measurement unreliable.
Every type of ultrasonic flow meter varies greatly in price but are often inexpensive to use and maintain because they do not use moving parts, unlike many mechanical flow meters, so are virtually maintenance free. They are ideal for applications involving toxic chemicals or ultra pure liquids where breaking into the pipe to install a flowmeter would be undesirable either due to the danger aspect or fear of contamination. It may also be more convenient to use an this particular system in applications involving high working pressures and temperatures where installing in-line devices would be problematic.
Typical applications include liquid flow measurement in full pipes, measurement of clean liquids, including water, wastewater, oils, solvents, acids, hydrocarbons and chemical, monitoring and controlling of HVAC systems. Our ultrasonic flow metering systems are ideal for applications in which disruption of flow is not an option.
All Flowquip’s ultrasonic flow meters are non-invasive, with sensors that clamp on to the side of the pipe. This avoids the need to cut into the pipe and interrupt the flow. One of our most popular ultrasonic meters is the KATflow 200, which is a handheld clamp-on flow meter. Fully portable and light weight, it is ideal when working at height or in small spaces. Sensor sets are available for pipelines from 10mm to 3 metres diameter.
An ultrasonic flow meter is ideal for applications where flow rates are required to be recorded over long periods of time. The KATflow 200 incorporates a data logging function with options for 30000 or 100000 measurements. Software is also provided to allow the user the facility to download the logged data to a PC. A certificate of calibration can be supplied with all new ultrasonic flowmeters offered by Flowquip. Additionally, Flowquip offer a flow meter calibration service. Our in-house, purpose-built and fully-certified calibration rigs mean that most types of flow meter, including ultrasonic, can be re-calibrated and a new calibration certificate issued.
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