Advantages and Limitations of Two Types of Flow Meters by Dayu Electronics
With the development of automation and information technology, the traditional measurement techniques and methods of Dayu Electronics flow instruments have been further developed and improved. New technologies such as ultrasonic and electromagnetic have opened up new fields for flow measurement, making flow instruments increasingly intelligent and giving rise to many new types of flow meters. However, each type of flow meter has its advantages and limitations. The following are the advantages and limitations of two different flow meters from Dayu Electronics.
1. Electromagnetic Flow Meter
The electromagnetic flow meter is manufactured based on Faraday's law of electromagnetic induction. When a conductive fluid flows in a magnetic field, an induced electromotive force is generated. Using a pair of electrodes to measure the induced electromotive force, the flow rate through a certain cross-sectional area can be determined.
Advantages of electromagnetic flow meters: Electromagnetic flow meters have no pressure loss, require shorter straight pipe runs, offer a wide rangeability, are easy to apply, and are cost-effective. In addition, they are highly responsive, capable of measuring instantaneous pulsating flow, and exhibit good linearity. Furthermore, the induced voltage signal is directly proportional to the average flow velocity of the medium being measured, resulting in high measurement accuracy.
Limitations of electromagnetic flow meters: The medium measured by an electromagnetic flow meter must be conductive, with a conductivity greater than 5 μs/cm. Measuring media with flow velocities below 0.1 m/s is extremely difficult. Due to limitations of electrical insulation materials and lining materials, general-purpose electromagnetic flow meters have certain requirements for medium temperature. During use, magnetic objects must be kept away to avoid affecting the sensor's working magnetic field and flow signal.
An ultrasonic flow meter is an instrument that measures flow by detecting the effect of fluid flow on ultrasonic pulses. Depending on the signal detection method, it can be classified into propagation velocity methods (time difference method, phase difference method, frequency difference method), Doppler method, cross-correlation method, and others.
Advantages of ultrasonic flow meters: Ultrasonic flow meters offer advantages that other flow meters cannot match, such as no pressure loss, wide rangeability, identical accuracy for bidirectional measurement, and the ability to measure pulsating flow. Additionally, they can measure non-conductive liquids, complementing electromagnetic flow meters that require unobstructed measurement. They are particularly suitable for large-diameter, high-flow-rate measurements, with pipe diameters ranging from centimeters to meters. They can be used for non-contact measurement, making them suitable for highly corrosive, flammable, and explosive media. Ultrasonic flow meters have been well applied in the high-pressure natural gas field.
Limitations of ultrasonic flow meters: When the measured liquid contains bubbles or other impurities, measurement accuracy can be affected, requiring straight pipe sections of 10D and 5D before and after the transmitter, respectively. Ultrasonic flow meters have a complex structure and are relatively expensive.