Commonused flow meter for sewage treatment

Flow meter is one of the instruments that are often used in sewage treatment. There are many flow meters according to the working principle, it is necessary to choose the appropriate flow meter according to the actual working conditions. Let's talk about the six commonly used flowmeters for sewage treatment. 

Magnetic flow meter

Electroelectromagnetic flow meter is a flow measurement instrument based on electromagnetic induction. It is composed of sensors and transmitters. 

1. Famous brand 

Famous brand mainly include: E+H, Yokogawa, Sosemount, Siemens, Emerson, ABB ect. 

2. Operational princilple 

The basic principle of the electromagnetic flowmeter is: outside of general non-magnetic materials, a pair of magnetic poles n and s are installed, so that to generate magnetic fields. When the conductive liquid flows through the pipe, the magnetoinductive potential is due by the fluid cutting of magnetic lines, the potential thus induced is drawn by two electrodes perpendicular to the magnetic pole, when the strength of the magnetic field is unchanged, the pipe diameter is certain, the magnitude of this induction potential is only related to the flow rate, passing the magnitude of this induction potential to the display instrument can read the flow. 

3. Advantage 

(1) Measure movable parts and fluid in the catheter, so pressure damage is small, there is no mechanical inertia, so it is sensitive. 

(2) Measurement range: range ratio usually 10: 1 , the max value is 100:1 , flow speed range usually 1-6m/s, can be extend to 0.5-10m/s; flow range. From 90ml/h to over 100 thousand m3/h; pipe diameter range 2mm to 2400mm or 3000mm.

(3) The liquid volume flow rate containing solid particles, suspended objects, or acid, alkali and salt solutions with a certain electrical conductivity can be measured. The pulsation flow rate can also be measured and can be measured in two directions.

(4) There is a linear relationship between flow signal and fluid volume flow, so the instrument has a uniform scale, the volume flow of the fluid is independent of the physical properties and flow state of the medium, therefore, the electromagnetic flow meter can be used to measure the volume flow of other conductive liquids only after water calibration without correction.

(5) Lower front straight section than most other flow meters.

4. Short coming

(1) Use temperature and pressure should not be too high;

(2) The application range is limited, can not be used to measure the flow of non-conductive fluids such as gas, steam and petroleum products, and fluids containing more large bubbles;

(3) The flow velocity and velocity distribution do not meet the set conditions;

(4) It is difficult to amplify and measure the current induction potential of orders of magnitude against the interference signal when too low, the instrument is also prone to zero-point drift;

(5) The signal of the electromagnetic flowmeter is relatively weak, and a slight external interference can affect the accuracy of the measurement.