Reasons for the decrease of accuracy in the Measurement of Turbine Flowmeter corresponding solutions

     A turbine flow meter is a type of turbine that is supported by bearings at the center of the measuring pipe. When the fluid flows through the pipe, it impacts the turbine blades and drives the turbine to cause the turbine to rotate against the fluid resistance torque and the friction torque. Within a certain flow range, for a given fluid medium viscosity, the rotational angular velocity of the turbine is proportional to the fluid flow rate. Thus, the fluid flow rate can be obtained by the rotational angular velocity of the turbine, whereby the flow of fluid through the conduit is ultimately achieved by calculation.
    Since the turbine flowmeter is sensitive to the conditions on site, the user should meet its ideal requirements with great satisfaction, so as to maintain the degree of factory instrumentation and obtain the desired measurement data. When the temperature pressure of the fluid medium differs greatly from the reference condition, the volume change of the sensor housing can be calculated according to the material and temperature pressure of the sensor, and the meter reading can be corrected. When the viscosity of the fluid medium is different from the viscosity of the calibration fluid, the viscosity correction curve provided in the installation and operation instructions shall be corrected.
     Moreover, the turbine flowmeter has certain requirements for the length of the straight pipe section upstream and downstream in the measurement, and it is required to meet the installation requirements, especially when the user demands high precision. The meter displays the volumetric flow under media operating conditions. For standard volume flow or mass flow, density compensation is also required.
     The accuracy of the turbine flowmeter during use is reduced, which may be due to the following reasons:

1. The fibrous or viscous impurities in the fluid are attached to the rotating part of the flowmeter, so that the rotational resistance is increased, causing the indication value of the meter to decrease, and a negative error occurs, which is unfavorable to the supply side of the fluid.

2. The change of fluid temperature and pressure may cause the liquid in the pipeline to escape the air contained in the pipeline or because the pressure inside the pipeline is lower than the saturated vapor pressure of the fluid, causing some of the liquid to become steam, or may be caused by the negative pressure of the medium. The gas is sucked into the pipeline, and these gases flow with the liquid to be measured, causing the indication value of the meter to increase, and a positive error occurs, which is unfavorable to the demand of the fluid.

3, the medium generally has some impurities, the bearing, the shaft should wear, so that the gap between the two increases, the dynamic balance of the moving parts is destroyed, the speed decreases, or the dirt enters the gap, so that the motion resistance increases The speed drops. For these reasons, the display value of the meter is reduced, and a negative error occurs, which is unfavorable to the supplier of the fluid.

4. The harsh working environment will also have a large impact on the measurement results, such as electromagnetic field interference, dust, high temperature, vibration, humidity, etc., which may cause malfunction or malfunction of the turbine flow sensor, directly causing the indication error of the turbine flowmeter. The error is positive or negative, may not be obvious, or may fail completely. For the above phenomenon, when it is more serious, problems can be found from the comparison of the working state of the process, and it is easy to take corresponding measures. However, in the early stages of the problem, problems cannot be discovered without special measures.
In summary, Kaifeng AFT Instrument Co., Ltd. based on the principle of turbine flowmeter and years of field work experience, it is recommended that users for the relatively dirty fluid or liquid that may generate gas, when installing the flowmeter, it can be in it Install filter or air eliminator and air collector upstream to strengthen daily maintenance work, regularly clean the filter, remove gas or debris from the air eliminator and collector, and ensure the normal operation of the flowmeter. In the initial stage of installation of the turbine flowmeter, a pair of pressure measuring ports are added to the pipe wall of the pipe diameter of the upstream and downstream of the flowmeter. When necessary, it is connected with the differential pressure gauge. In the working state, the flowmeter indication value and difference are recorded. The contrast relationship between the pressure gauge indication values. If everything is normal at this time, use this comparison relationship as the basis for checking whether the flowmeter works normally. This comparison relationship is measured periodically and the record is tracked. If the flowmeter indication value is too small under the same differential pressure gauge indication value, the flowmeter may be suspected to be malfunctioning. The method of checking the flowmeter's sensor can be done by first checking the transmitter. The method is to remove the sender separately, input a known signal, and find the problem by comparing the output values. If the fault cannot be eliminated for a short time, you can replace it with a new one. If it is not the cause, the flow meter should be removed from the process line and further carefully examined for symptomatic treatment.