Several reasons for the error of turbine flowmeter

(1) The liquid in the pipe is not full. Due to the lack of back pressure or the poor installation position of the flow sensor, the liquid in the measuring pipe cannot be filled. The fault phenomenon has different manifestations due to the degree of non-filling and the flow situation. If a small amount of gas is in a stratified flow or wavy flow in the water pipe, the fault phenomenon is manifested as an increase in error, that is, the flow measurement value does not match the actual value; if the flow is a bubble flow or a plug flow, in addition to the measurement value not matching the actual value, the output will fluctuate due to the gas phase covering the electrode surface for a moment; if the gas phase of the flow cross-sectional area increases locally during the stratified flow of the horizontal pipeline, that is, the liquid does not fill the pipe to a certain extent, the output will also fluctuate. If the liquid does not fill the pipe more seriously, causing the liquid level to be below the electrode, the output will be overfilled.

(2) The liquid contains solid phase. The liquid contains solids such as powder, particles or fibers. The possible faults are: ① Slurry noise; ② Electrode surface contamination; ③ The conductive deposit layer or insulating deposit layer covers the electrode or lining; ④ The lining is worn or covered by deposits, and the flow cross-sectional area is reduced.

(3) Electromagnetic flowmeters should be used with caution for liquids that may crystallize. Some chemical materials that are prone to crystallization can be measured normally under normal temperature conditions because the conduits that transport the fluid have good heat insulation and will not crystallize during the insulation operation. However, it is difficult to heat and insulate the measuring tube of the electromagnetic flow sensor. Therefore, when the fluid flows through the measuring tube, it is easy for the inner wall to form a layer of solid due to cooling. Since the crystallization problem also exists when using flowmeters based on other principles, in the absence of other better methods, an "oring" electromagnetic flow sensor with a very short measuring tube can be selected, and the heat insulation of the upstream pipeline of the flowmeter can be strengthened. In terms of pipeline connection methods, consider the convenience of disassembly and assembly of the flow sensor so that it can be easily removed for maintenance in the event of crystallization. (end)