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Effect of medium flow rate on the selection of Coriolis mass flowmeter

The Coriolis mass flowmeter is a meter that measures the mass flow using the Coriolis principle. The Coriolis principle describes the force that is different from the centrifugal force when the object moves linearly along the radius in the rotating system. For Coriolis force.
The Coriolis mass flowmeter has high measurement accuracy, and the measurement is not affected by the physical properties of the medium, and there is no requirement for the length of the straight pipe section on the upstream and downstream. Moreover, the Coriolis mass flowmeter is a highly intelligent instrument. In addition to mass flow, the transmitter can output process parameters such as volume flow, density, temperature, viscosity and concentration converted into 4-20 mA or pulse signals or bus signals. .
It can also output the empty tube detection signal converted into relay contact or NAMOUR signal; even without the batch controller, the valve can be directly controlled by two-stage opening and closing. Therefore, Coriolis mass flowmeters are widely used in various industrial sectors such as chemical, pharmaceutical, energy, rubber, paper, food, etc., and are suitable for use in batching, loading, and trade transfer.
Coriolis mass flowmeter can be divided into single tube type and double tube type according to the number of measuring tube segments; according to the shape of the measuring tube, it can be divided into curved shape and straight shape, and the curved measuring tube is also divided into Ω shape, S shape, J shape, triangle. According to the measuring tube material, there are 316L, 904L, C-22 alloy, titanium and zirconium; according to the flowmeter installation method, there are thread, flange, clamp, CajonVCO, Swagelok and so on. According to the actual project conditions and process parameters, select the appropriate mass flowmeter of shape, material, nominal diameter, nominal pressure and installation method.
When the Coriolis mass flowmeter is operating normally, the vibration of the measuring tube causes the Coriolis force to be generated in the measuring medium in the tube. The greater the Coriolis force, the greater the friction between the flow medium and the wall of the measuring tube, and the greater the pressure loss of the flow meter produced, and the size of the Coriolis force is proportional to the flow rate of the measuring medium. Therefore, the influence of the measured medium flow rate should be considered when selecting the Coriolis mass flowmeter. The influence of the medium flow rate on the selection of the Coriolis mass flowmeter is related to the Coriolis mass flowmeter measurement principle.
Obviously, the Coriolis mass flowmeter is mainly used to measure the mass flow rate of the medium or the volume flow calculated by the output. The selection parameters provided by the process professional only involve the medium mass flow rate or the volume flow rate; therefore, the influence of the medium flow rate is ignored. The Coriolis mass flowmeter has a small amplitude of the measuring tube, which can be regarded as no moving parts and no obstruction, and its measured value is not affected by the flow field inside the pipe.
Therefore, various non-Newtonian fluids as well as viscous and particulate-containing slurries can be measured, and the flow range ratio can be large. However, the maximum measured value of a Coriolis mass flowmeter with a nominal diameter is actually limited, and the medium flow rate is a factor. We can choose the flowmeter measuring tube shape and nominal diameter according to the medium flow rate.
In summary, when selecting a Coriolis mass flowmeter, it is necessary to consider whether the pressure loss is allowed by the entire process flow. The requirement to limit the pressure loss limits the upper limit of the medium flow rate at a nominal diameter. Or, under the requirement of ensuring the medium mass flow rate or the upper volume flow rate, select a larger nominal diameter to expand the circulation area.
In addition, the flowmeter has a small nominal diameter, high measurement accuracy, and relatively low price; the nominal diameter is large, although the flowmeter pressure loss is reduced, but the measurement accuracy is reduced, and the procurement cost is increased. Therefore, it is necessary to strike a balance between accuracy and pressure loss to calculate the most appropriate nominal diameter.

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