Vortex flowmeter is also called Karman vortex flowmeter. It is a kind of separation type flowmeter made by using the principle of fluid natural oscillation. When a fluid flows at a sufficiently large flow rate through an object that is perpendicular to the direction of fluid flow, if the size of the object is appropriate, a vortex train that is neatly arranged and turns in opposite directions will be generated along two parallel straight lines behind the object.
Among them, S is the Strouhal number, V is the average flow velocity in the pipeline, and d is the width of the flow surface of the column. Therefore, by measuring the frequency of the vortex, the flow velocity of the fluid can be known and the flow rate of the fluid can be measured.
Sensor installation considerations
(1) The sensor should be installed horizontally or vertically (fluid flow should be from bottom to top) on the pipe corresponding to the nominal diameter.
(2) When the vortex flowmeter is used for flow adjustment, special attention should be paid to installing the flow control valve behind the sensor, otherwise it is easy to generate jets when the flow rate is small, causing the flow of the medium and the opening of the valve when the flow is adjusted. Inverse fault phenomenon.
(3) The flow meter should be equipped with a certain length of straight pipe section upstream and downstream when it is installed.
(4) The flow meter can not be installed on the pipeline with strong vibration, so as not to affect the measurement accuracy.
(1) In the water supply system, the flowmeter is generally installed in the instrument well. In order to prevent the water metering well from damaging the instrument in the rainy season, the instrument should be removed from the instrument well as far as possible, or a separate sensor should be used.
(2) When there are high-power motors near the flowmeter, in order to avoid power frequency interference, in addition to adding shielding to signal transmission cables, the signal transmission method should use DC signals as much as possible.
(3) The technical parameters of the flowmeter should be well documented and managed, such as the KQ coefficient and full-scale frequency of the flowmeter. The loss of these data will cause great difficulties for the maintenance of the instrument.
(4) When a flameproof flow sensor is used, the instrument housing must not be opened on site in the on state. During the inspection, the housing must be protected. In particular, the flameproof joint cannot be damaged.
(5) The detection element should be periodically taken out of the pipeline and cleaned with alcohol or gasoline.