2019-11-27 14:35:32

Use and promotion of electromagnetic flowmeter

The intelligent electromagnetic flowmeter is a fully intelligent electromagnetic flowmeter developed by our company using advanced technology at home and abroad. Its all-Chinese electromagnetic converter core adopts high-speed central processing unit, which has fast calculation speed, high precision and reliable measurement performance. The converter circuit design adopts the latest international technology, the input impedance is up to 1015 ohms, the common mode rejection ratio is better than 100db, and the external interference and 60Hz/50Hz interference suppression ability is better than 90db, which can measure the lower conductivity fluid medium flow. The sensor adopts a new non-uniform magnetic field technology and a special magnetic circuit structure. The magnetic field is stable and reliable, and the volume is greatly reduced, the weight is reduced, and the flowmeter has the characteristics of small size and light weight. Adhering to the enterprise spirit of "seeking truth, hard work, innovation and development", we insist on "customer first, technology first, high quality, first-class service", we will provide you with first-class products and first-class service.

Vortex flowmeter working principle

The working principle of the vortex flowmeter is to arrange a vortex generator in the fluid, so that the vortex is alternately generated on both sides of the body, and the vortex column is asymmetrically arranged downstream of the vortex generator to generate a certain frequency, by the formula f= St*v/(1-1.27d/D)*d, (St is the Strauhal number, which is a dimensionless number, related to the vortex generator and Reynolds number; v is the flow velocity; d is the incident head width; D is the nominal diameter) to get the flow rate.

In general, the vortex flowmeter output signal (frequency) is not affected by changes in fluid properties and composition, which means that the meter factor is only related to the shape and size of the vortex generator and the Reynolds number. Its advantages are: simple and firm structure, convenient installation and maintenance; suitable for a variety of fluids, liquid, gas, steam and some mixed phases are applicable; high precision, generally up to ± 1% R; flow range is wide, up to 10 : 1 or 20:1 or more; low head loss; no zero drift; relatively cheap price; disadvantage: not suitable for low Reynolds number Re <20000, limited use of high viscosity, low flow rate, small diameter The requirements for the environment are high, and places with vibration should be eliminated as much as possible, and the upstream side needs to have a long straight pipe section; the meter factor is lower, and the larger the diameter, the lower the diameter. The signal resolution is reduced, so the aperture should not be too large, generally used in DN15~DN300mm.

How the turbine flow meter works

The working principle of the turbine flowmeter: the fluid flows through the sensor housing. Since the blade of the impeller has a certain angle with the flow direction, the momentum of the fluid causes the blade to have a rotational moment. After the friction torque and the fluid resistance are overcome, the blade rotates, and the rotational speed is stabilized after the torque balance. Under certain conditions, the rotational speed is proportional to the flow rate. Due to the magnetic permeability of the blade, it is in the magnetic field of the signal detector (composed of permanent magnet and coil). The rotating blade cuts the magnetic field lines and periodically changes the coil. Magnetic flux, so that the two ends of the coil induce electricity

Pulse signal, which is amplified and shaped by the amplifier to form a continuous rectangular pulse wave with a certain amplitude, which can be transmitted to the display instrument to display the instantaneous flow rate and cumulative amount of the fluid. Within a certain flow range, the pulse frequency f is proportional to the instantaneous flow rate Q of the fluid flowing through the sensor. The flow equation is: Q = 3600 × f / k

In the formula:

F——pulse frequency [Hz];

K——the meter factor of the sensor [1/m], given by the checklist. If [1/L] is used, Q=3.6×f/k

Q——the instantaneous flow rate of the fluid (under working condition) [m3/h];

3600 - conversion factor.

The meter factor of each sensor is filled in the verification certificate by the manufacturer, and the k value is set in the matching display meter to display the instantaneous flow rate and the cumulative total amount.