The electromagnetic flowmeter has a large measuring range, usually 20:1~50:1, and the optional flow range is wide; the diameter of the electromagnetic flowmeter is wider than other types of flowmeters, from a few millimeters to 3 meters; the positive and negative two-way flow can be measured. The pulsating flow rate can also be measured as long as the pulsation frequency is much lower than the excitation frequency; the meter output is linear in nature; it is easy to select the material type of the fluid contact member, and can be applied to corrosive fluids and the like. Since the electromagnetic flowmeter measures much more with suspended solids or dirt than other flow meters, the probability of failure of the inner wall adhesion layer is relatively high. If the electrical conductivity of the adhesion layer is close to the liquid conductivity, the instrument can output the signal normally, but only change the flow area to form a hidden fault of the measurement error; if it is a high conductivity adhesion layer, the electromotive force between the electrodes will be short-circuited; if it is an insulating adhesion layer The surface of the electrode is insulated to disconnect the measuring circuit. The latter two phenomena will make the meter inoperable.
Liquid turbine flow meter classification and function description
Keywords: liquid turbine flowmeter, diesel liquid turbine flowmeter, pure water liquid turbine flowmeter
First, the liquid turbine flowmeter overview
The liquid turbine flowmeter is the main type of impeller flow (flow rate) meter, and the impeller type flowmeter also has an anemometer and a water meter. The TUF consists of a sensor and a conversion display. The sensor uses a multi-blade rotor to sense the average flow rate of the fluid, thereby deriving the flow or total amount. The rotational speed (or number of revolutions) of the rotor can be detected mechanically, magnetically, and photoelectrically and displayed and transmitted by the reading device.
Second, liquid turbine flowmeter classification
According to the classification of instrument functions, SDLWGY series turbine flowmeters can be divided into 2 categories.
1, turbine flow sensor / transmitter
2, intelligent integrated turbine flowmeter
Third, the liquid turbine flowmeter function description
1, turbine flow sensor / transmitter
This type of turbine flow product itself does not have a live display function, only the flow signal is transmitted far. The flow signal can be divided into pulse signal or current signal (4-20mA); the instrument is low in price, high in integration and small in size, and is especially suitable for use with computer control systems such as secondary display, PLC, DCS.
Test equipment: one 500MΩ insulation resistance tester, one multimeter.
(1) When the pipeline is filled with medium, measure the resistance between terminals A, B and C with a multimeter. The resistance between A-C and B-C should be equal. If the difference is more than 1 time, there may be leakage of the electrode, condensation on the outer wall of the measuring tube or the junction box.
(2) In the case of lining drying, measure the insulation resistance between A-C and B-C with MΩ meter (should be greater than 200MΩ). Then use a multimeter to measure the resistance of the two electrodes in terminals A and B and the measuring tube (should be in short-circuit communication). If the insulation resistance is small, indicating that the electrode is leaking, the entire flowmeter should be returned to the factory for repair. If the insulation is reduced but there is still more than 50 MΩ and the inspection result of step (1) is normal, the outer wall of the measuring tube may be damp, and the inside of the outer casing may be dried by a hot air blower.
(3) Use a multimeter to measure the resistance between X and Y. If it exceeds 200 Ω, the excitation coil and its lead wire may be open or poorly connected. Remove the terminal block check.
(4) Check the insulation resistance between X, Y and C, which should be above 200 MΩ. If it is lowered, dry the inside of the casing with hot air. In actual operation, the decrease in coil insulation will result in increased measurement error and unstable instrument output signal.
(5) If it is determined that the sensor is faulty, please contact the manufacturer of the electromagnetic flowmeter. The general site cannot be solved and needs to be repaired by the manufacturer.