渣浆泵堰测量流量的特点

①有较好的精度，直角三角堰为土1% ~ +2%左右，矩形堰和全宽堰为土1%一土3%，如果经标定精度可达+0. 5%一士1.5%。

②阻力损失小，可用于低扬程大流量泵的流量测量。

③测量流量大，可用于特大流量的测量。

④测量时需要较长的稳定时间，测量时间长。

⑤不能测量瞬时流量，只能测量一段时间内的平均流量。

⑥堰的体积较大，占地面积大。

⑦只能用在开式试验回路中。 

4.电磁流量计

(1) 工作原理  

是基于法拉第电磁感应定律，当导电流体流过两磁极之间的管道时，切割了感场，在电极上产生了与流体流速  成正比的感应电动势E，如图8-17所示。

E = KBDv 
式中E--感应电动势;

K---仪表常数;  
      B--感应电动势；

v --平均流速;

 D-测量管内径。

当磁感应强度为常数时，感应电动势E  正比于平均流速。.感应电动势E由电极检出，传送给二次转换器，就可直接转换成被测量的流量值。所以在实际使用中，都需要配备二次转换器，直接就能显示出流量值。

(2)电磁流量计流量测量特点

①精度较高，可高于+0.5%。

②它不受流体的压力、湿度、黏度、密度等的影响，可以用于污蚀液体的测量。

③测量范围大。

④变送器上、下游直管长度较短，上游≥5D， 下游≥3D。

⑤阻力损失小，可用于扬程较低的泵的流量的测量。

⑥反应快，可测得瞬时流量，并可用于闭式测试回路中的流量测量。

⑦电磁流量计为间接测量的流量计，所以必须经过标定才能使用，并且在使用过程中，还需定期标定，对精度高于+0. 5%的流量计，每年标定次，对精度低于+0. 5%的流量计，每二年标定一次。

⑧价格较高。

⑨不能在有强磁场的环境下使用。

5.涡轮流量计

(1)工作原理  渣浆泵厂家

涡轮流量传感器的结构如图8-18所示。当流体流经传感器时，冲动涡轮旋转使导磁的叶片周期性地改变检测器中磁路的磁阻值，使通过感应线圈的磁通量随之变化，在感应线圈  

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