The reason for the decrease in measurement accuracy of turbine flowmeter

NegotiableUpdate on 03/21

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Overview

The reason for the decrease in measurement accuracy of turbine flow meters is that the accuracy of turbine flow meters is determined under reference conditions (or standard operating conditions). Regarding turbine flow meters, the reference conditions are generally environmental conditions (ambient temperature 15 ° C~35 ° C, relative humidity 45%~75%, atmospheric pressure 86 kPa,~108 kPa, no electric field, magnetic field interference, no vibration) and power source conditions (220 V ± 10% or 110 V, 50 Hz ± 1 or 24 VDC). Fluid conditions (fluid calibration pipeline is an industrial circular tube, single-phase Newtonian fluid, fully filled, fully developed turbulent velocity, axisymmetric distribution, no eddies, no interference, constant flow rate. Calibration fluids are usually water, oil, and air. As needed, there are sufficient straight pipe sections upstream and downstream of the turbine flow meter. The fluid temperature is generally room temperature, and the fluid pressure is generally below 0.25 MPa). It is obvious that turbine flow meters The actual operating conditions are usually different from the reference conditions, which may lead to changes in the accuracy of the turbine flowmeter. Turbine flow meters are sensitive to on-site conditions, and users should try to meet their requirements to maintain factory accuracy. When the temperature and pressure of the fluid medium are significantly different from the reference conditions, the volume change of the sensor housing can be calculated based on the material and temperature of the sensor, and the reading value of the instrument can be corrected. When the viscosity of the fluid medium is different from that of the calibration solution, it should be corrected according to the viscosity correction curve provided by our company. Turbine flow meters have certain requirements for the length of upstream and downstream straight pipe sections, which should be managed, especially when users require high precision, the instrument displays the volumetric flow rate of the medium under operating conditions. For

Product Details

The reason for the decrease in measurement accuracy of turbine flowmeter

The accuracy of the turbine flowmeter is determined under reference conditions (or standard operating conditions). Regarding turbine flow meters, the reference conditions are generally environmental conditions(ambient temperature15°c~35°cRelative humidity45% 75%Atmospheric pressure86 kpa、~ 108 kpaNo electric field, magnetic field interference, no vibration)And power source conditions( 220 v±10%perhaps110 v、50hz±1perhaps24 VDC )Fluid conditions(The fluid calibration pipeline is an industrial circular tube, single-phase Newtonian fluid, fully filled, fully developed turbulent velocity, axisymmetric distribution, no vortex, no interference, and constant flow rate. The calibration fluid is usually water, oil, or air.

涡轮流量计测量精度下降的原因

As needed,Turbine FlowmeterThere are sufficiently long straight pipe sections upstream and downstream. The fluid temperature is generally room temperature, and the fluid pressure is generally lower than0.25 MPa）It is evident that the actual operating conditions of a turbine flowmeter are often different from the reference conditions, which may result in variations in the accuracy of the turbine flowmeter.
Turbine flow meters are sensitive to on-site conditions, and users should try to meet their requirements to maintain factory accuracy. When the temperature and pressure of the fluid medium are significantly different from the reference conditions, the volume change of the sensor housing can be calculated based on the material and temperature of the sensor, and the reading value of the instrument can be corrected.
When the viscosity of the fluid medium is different from that of the calibration solution, it should be corrected according to the viscosity correction curve provided by our company.
Turbine flow meters have certain requirements for the length of upstream and downstream straight pipe sections, which should be managed, especially when users require high precision, the instrument displays the volumetric flow rate of the medium under operating conditions. For standard volumetric and mass flow rates, density correction is also required.

Temperature of turbine flowmeter during useThe decline may be due to the following reasons:
1There are usually some impurities in the medium, which cause wear on the bearings and shafts, increase the gap between the two, disrupt the dynamic balance of the moving parts, reduce the speed, or allow dirt to enter the gap, increasing the resistance to motion and reducing the speed. These reasons all lead to a decrease in instrument display values, resulting in negative errors that are detrimental to the fluid supplier.
2Changes in fluid temperature and pressure may cause liquid in the pipeline to escape from the air in the pipeline, or some liquid may turn into steam due to the pressure inside the pipeline being lower than the saturated vapor pressure of the fluid, or external gas may be caused by negative pressure of the medium. In the suction pipe, these gases flow together with the liquid to be measured, resulting in an increase in the instrument reading and a positive error, which is not conducive to the demand for the liquid.
3Fibrous or viscous impurities in the fluid adhere to the rotating part of the flowmeter, increasing the rotational resistance and causing a decrease in the instrument's indication value, resulting in negative errors and being detrimental to the fluid supplier.
4The working environment is relatively harsh, such as electromagnetic field interference, dust, high temperature, vibration, humidity, etc., which may cause misoperation or failure of the turbine flow sensor, directly causing the indication error of the turbine flow meter. The error may be positive or negative, may not be significant, or may completely fail. For the above phenomenon, in more serious cases, problems can be identified by comparing the process work status, making it easy to take corresponding measures. However, in the early stages of the problem, it cannot be discovered without taking special measures.
Based on the principle of turbine flow meters and on-site work experience, we recommend that during the initial installation of turbine flow meters, both upstream and downstream of the flow meters should be installed2Add a pair of pressure measuring ports on the wall of the double diameter pipe, and connect a differential pressure gauge when needed. Record the comparison between the flow meter reading and the differential pressure gauge reading during operation. If everything is normal at this time, please use this comparison relationship as the basis for checking whether the flowmeter is working properly.