3/20/2024 0 Comments Flow meters![]() A special form which is independent of the horizontal flow direction is the cup cross anemometer. The propeller-like impeller is held directly in the flow, whereby for many devices it is essential to pay attention to the direction of the flow. Some of these devices can also determine the volume flow in the case of the fixed flow cross-section. Mobile devices are used in the fields, on the construction sites or airfields or in buildings to check the ventilation ducts. They are permanently installed on buildings or on wind turbines and can be rotated into the flow by coupling them to a wind direction meter or wind direction indicator. These devices are often used for outdoor wind measurements. The flowmeter that determines the velocity of the medium from how fast a specially shaped impeller is moved through the flow is the impeller anemometer. The volume flowing through the pipe can be determined from the flow velocity and the pipe cross-section. From this the flow velocity can be determined. If the static pressure of the not moving medium, which is also measured, is subtracted from this dynamic pressure, the differential pressure is obtained. The pressure measurement works via a pipe with specially arranged openings, which detects and records the pressure of the flowing medium. The flow meter that determines the flow velocity by means of the pressure difference is the Pitot tube anemometer. Both the ultrasonic flowmeter and the magnetic inductive flowmeter function as measuring devices without obstructing the flow. Hot-wire anemometers with their thermal sensors are particularly suitable as flow meters for low velocities of the gaseous media. Liquid volumes and average flow velocities for gases in the range of 5 m/s to 20 m/s can be measured well with the impellers. The flow meters with Pitot tube are well suited for strong flows and for gases with high particle content. Flow meters with Pitot tube, impeller and hot wire are among those devices where the sensor is positioned directly in the flow and influences it to a greater or lesser extent. Various measuring principles can be used to measure the flow velocity and the volume flow. Should the flow meter be calibrated and adjustable?īelow, some flow meters are briefly described according to their operating principle. Should the measured values be stored or transmitted? Should the measurement be carried out during a running process and should the process be influenced? What accuracy is expected from the flowmeter? Which flow velocities should be measured? If so, may the flowmeter protrude into the pipe cross-section? Does the material flow through a completely filled pipe cross section? Is the material gaseous, liquid or bulk? Should the flowmeter be permanently installed at one point or should it be applied for the measurements at different points? In order to narrow down the choice for your own requirements, it is advisable to first clarify the measuring conditions. Mobile devices are suitable for occasional testing, measurement at different locations and for troubleshooting in existing plants and systems.įlow meters are used in many different areas. These devices and those used for continuous monitoring and control of processes are called stationary flow meters, because they are permanently used at the same place. These flow meters are used to record the quantity and must be calibrated because of the volume-dependent prices. With specially equipped devices it is also possible to measure the bulk materials able to flow during transport in manufacturing or storage processes.Įven those who have little to do with the flow meter, for sure have already observed the flow meter at the fuel dispenser while refueling and possibly read the water meter or gas meter before paying the bills for the water and gas quantities used. Often the flow meter is designed for a certain state of the flowing material, i.e. Among other things, flow meters can be differentiated according to the type of the medium to be measured and the measuring principle. A flow meter is used to determine the velocity and, under certain conditions, also the quantity of the flowing medium.
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