Partially Filled Pipe Magnetic Flow Meter

RBEF-P Type Partially filled (Open Channel) Electromagnetic Flow Meter(EMF) Principle:

 In the case of a partial-filled pipe, when the electromagnetic flowmeter measures the flow rate, as the fluid level height in the insulating pipe changes, the distribution of the flow is uneven, and the distribution of the weight function is also changing, so the change in the flowing liquid level leads to the accuracy of the measured flow rate. Therefore, in order to obtain accurate flow rate signal parameters, measuring the liquid level parameters is the key to solving the measurement of the electromagnetic flowmeter for non-full pipes. In this way, the flow rate signals at different liquid levels can be averaged according to the weight function. After obtaining the flow rate parameters and liquid level parameters, the measurement of the fluid flow in the case of a non-full pipe can be achieved.

1. Level meter measurement principle

This partial-filled tube electromagnetic flowmeter uses an ultrasonic level meter. Its working principle is to transmit energy waves through a device that can transmit energy waves (generally pulse signals). The energy waves are reflected by obstacles and a receiving device receives the reflected signals. The liquid (object) level change is determined by measuring the time difference of the energy wave movement process. The microwave signal is processed by an electronic device and finally converted into an electrical signal related to the liquid level. The primary probe transmits an ultrasonic pulse signal to the surface of the measured medium. The ultrasonic wave is reflected after encountering the measured medium (obstacle) during the transmission process. The reflected ultrasonic signal is detected by the electronic module. It is processed by special software, and the time difference between the emission of the ultrasonic wave and the echo is analyzed. Combined with the propagation speed of the ultrasonic wave, the distance of the ultrasonic wave propagation can be accurately calculated, and then the liquid level h can be reflected.

2 Flow rate measurement principle 

The flow rate measurement working principle of the partial filled tube electromagnetic flowmeter(EMF) is still based on Faraday's law of electromagnetic induction. When a conductor moves in a magnetic field, an induced electromotive force will be generated at both ends of the conductor in a direction perpendicular to the direction of the magnetic field and the direction of movement. The magnitude of the electromotive force is proportional to the conductor movement speed and the magnitude of the magnetic induction intensity. The fluid medium is equivalent to a conductor in motion. The direction of fluid flow is perpendicular to the direction of the electromagnetic field, and the induced voltage is proportional to the fluid flow rate.