Precautions for selecting electromagnetic flowmeter

Nowadays, in cities or industries, most electromagnetic flowmeters are used to measure discharged sewage. Electromagnetic flowmeters have high precision and long service life, making them the first choice in the environmental measurement industry. Correct selection of electromagnetic flowmeter can ensure better use of electromagnetic flowmeter, based on the chemical properties of the fluid medium, pipe diameter, flow range, lining material, electrode material and output signal, etc.

1. Measurable fluid media

Through the principle of electromagnetic flowmeter, we know that electromagnetic flowmeter can choose conductive liquid, and electromagnetic liquid can be used as long as the conductivity is greater than 5μ/cm. flow meter. However, the limitation of electromagnetic flowmeter is that it can only measure liquids, but cannot measure gases, steam, etc.

2. Selection of integrated or split type

Electromagnetic flowmeters are available in integrated and split types. The integrated type is generally used in good environment. The integrated electromagnetic sensor It is integrated with the converter. For the split type, the sensor and converter are separated. Generally, the split type is used in places where readings are not suitable. For example: the ambient temperature is too high, the pipeline vibrates greatly, the on-site environment is corroded, the flow meter is installed at high altitude, etc. In this case, a split type electromagnetic is used, and a 10m cable is connected to the converter to ensure that the converter is in a suitable environment.

3. Selection of caliber of sensor

In general, considering the convenience of installation, do not choose a reducer. But the premise is that the applicable flow velocity in the flow meter tube should be within the range of 0.3m/S ~ 10m/S. This choice is often suitable for newly designed projects. When selecting the flow rate, the current working conditions should be taken into consideration, as well as the situation when the equipment is operating at full load in the future. But sometimes the caliber of the sensor is chosen to be different from the caliber of the connected process pipeline. As follows:

(1) The flow rate in the pipeline is low and the process flow rate is relatively stable. In order to meet the requirements of the instrument for the flow range, the flow rate is locally increased at the flow meter and the sensor diameter is selected to be smaller than the process pipe diameter. Install reducers before and after the sensor.

(2) For large-diameter electromagnetic flowmeters, the larger the diameter, the higher the price. For situations where the flow rate in the pipeline is low and the process parameters are stable, a flowmeter with a smaller diameter can be used. This not only makes The flow meter operates in better working condition while reducing investment costs.

4. Selection of electrode materials: 316L electrode, tantalum electrode, HC electrode, platinum electrode, etc.

5. Selection of grounding ring material

The grounding ring material can be the same as the electrode material, and generally the material with the same corrosion resistance as the pipe material can be selected.

6. Selection of lining materials

Depending on the medium, you can choose: PO material, rubber material, PTFE material, polyurethane material, ceramic lining.