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渣漿泵堰測量流量的特點

①有較好的精度，直角三角堰為土1% ~ +2%左右，矩形堰和全寬堰為土1%一土3%，如果經標定精度可達+0. 5%一士1.5%。

②阻力損失小，可用于低揚程大流量泵的流量測量。

③測量流量大，可用于特大流量的測量。

④測量時需要較長的穩定時間，測量時間長。

⑤不能測量瞬時流量，只能測量一段時間內的平均流量。

⑥堰的體積較大，占地面積大。

⑦只能用在開式試驗回路中。 

4.電磁流量計

(1) 工作原理  

是基于法拉第電磁感應定律，當導電流體流過兩磁極之間的管道時，切割了感場，在電極上產生了與流體流速  成正比的感應電動勢E，如圖8-17所示。

E = KBDv 
式中E--感應電動勢;

K---儀表常數;  
      B--感應電動勢；

v --平均流速;

 D-測量管內徑。

當磁感應強度為常數時，感應電動勢E  正比于平均流速。.感應電動勢E由電極檢出，傳送給二次轉換器，就可直接轉換成被測量的流量值。所以在實際使用中，都需要配備二次轉換器，直接就能顯示出流量值。

(2)電磁流量計流量測量特點

①精度較高，可高于+0.5%。

②它不受流體的壓力、濕度、黏度、密度等的影響，可以用于污蝕液體的測量。

③測量范圍大。

④變送器上、下游直管長度較短，上游≥5D， 下游≥3D。

⑤阻力損失小，可用于揚程較低的泵的流量的測量。

⑥反應快，可測得瞬時流量，并可用于閉式測試回路中的流量測量。

⑦電磁流量計為間接測量的流量計，所以必須經過標定才能使用，并且在使用過程中，還需定期標定，對精度高于+0. 5%的流量計，每年標定次，對精度低于+0. 5%的流量計，每二年標定一次。

⑧價格較高。

⑨不能在有強磁場的環境下使用。

5.渦輪流量計

(1)工作原理  渣漿泵廠家

渦輪流量傳感器的結構如圖8-18所示。當流體流經傳感器時，沖動渦輪旋轉使導磁的葉片周期性地改變檢測器中磁路的磁阻值，使通過感應線圈的磁通量隨之變化，在感應線圈  

Characteristics of flow measurement by slurry pump weir

(1) it has good accuracy. The right angle triangular weir is about 1% ~ + 2% of soil, the rectangular weir and the full width weir are about 1% of soil and 3% of soil. If calibrated, the accuracy can reach + 0.5% of 1.5%.

② the resistance loss is small, which can be used for flow measurement of low head and large flow pump.

③ the measurement flow is large, which can be used for the measurement of extra large flow.

④ the measurement needs a long time of stability and measurement.

⑤ the instantaneous flow cannot be measured, only the average flow in a period of time can be measured.

⑥ the weir has a large volume and covers a large area.

⑦ it can only be used in open test circuit.

4. Electromagnetic flowmeter

(1) working principle

Based on Faraday's electromagnetic induction law, when the conductive fluid flows through the pipe between the two magnetic poles, the induction field is cut, and an induction electromotive force E proportional to the flow velocity of the fluid is generated on the electrode, as shown in Figure 8-17.

E = KBDv

Where e -- induced electromotive force;

K - instrument constant;

B -- induced electromotive force;

V -- average velocity;

D-measure the inside diameter of the tube.

When the magnetic induction intensity is constant, the induced electromotive force E is proportional to the average velocity. . the induced electromotive force E is detected by the electrode and transmitted to the secondary converter, which can be directly converted into the measured flow value. Therefore, in actual use, it is necessary to equip secondary converter to directly display the flow value.

(2) flow measurement characteristics of electromagnetic flowmeter

① the accuracy is higher than + 0.5%.

② it is not affected by the pressure, humidity, viscosity and density of the fluid, and can be used for the measurement of soiled liquid.

③ large measuring range.

④ the length of upstream and downstream straight pipes of the transmitter is short, upstream ≥ 5D, downstream ≥ 3D.

⑤ the resistance loss is small, which can be used to measure the flow of the pump with low head.

⑥ fast reaction, can measure the instantaneous flow, and can be used for the flow measurement in the closed test circuit.

⑦ the electromagnetic flowmeter is an indirect measurement flowmeter, so it can only be used after calibration. In the process of use, it needs to be calibrated regularly. For the flowmeter with accuracy higher than + 0.5%, it needs to be calibrated every year. For the flowmeter with accuracy lower than + 0.5%, it needs to be calibrated every two years.

⑧ high price.

⑨ it cannot be used in the environment with strong magnetic field.

5. Turbine flowmeter

(1) working principle: slurry pump manufacturer

The structure of turbine flow sensor is shown in Figure 8-18. When the fluid flows through the sensor, the impulse turbine rotates to periodically change the magnetic resistance value of the magnetic circuit in the detector, so that the magnetic flux through the induction coil changes accordingly