Reasons Affecting the Measurement Accuracy of the Roots Gas Flow Meter

Abstract: The information on the reasons affecting the measurement accuracy of the Roots gas flow meter is provided by the excellent flow meter and flow meter manufacturers and quotation manufacturers. Reasons affecting the measurement accuracy of Roots gas flowmeter 1 Principle of Roots gas flowmeter Roots gas flowmeter is a positive displacement gas flowmeter, which has the characteristics of high measurement accuracy, flexible installation and space saving. Roots gas flowmeter is mainly composed of meter. More flowmeter manufacturers choose models and price quotations. You are welcome to inquire. The following is the details of the reasons that affect the measurement accuracy of Roots gas flowmeters. Reasons affecting the measurement accuracy of Roots gas flowmeter 1 Principle of Roots gas flowmeter Roots gas flowmeter is a positive displacement gas flowmeter, which has the characteristics of high measurement accuracy, flexible installation and space saving. Roots gas flowmeter is mainly composed of measuring chamber, conjugate rotor and counting device and other components. The pressure difference between the inlet and outlet of the circulating gas between a pair of conjugate rotors installed in the measuring chamber (P in>Under the action of P out), the two rotors alternately bear the rotational torque. Each time the rotor rotates, it outputs four times the effective volume of the measuring chamber. The rotation of the rotor is transmitted to the mechanical counter through the magnetic seal coupling device and the deceleration mechanism, so as to display the cumulative volume of the output gas. Its measurement process and working principle are shown in Figure 1 (only a quarter cycle is shown in the figure). Fig.1 Working principle of Roots gas flowmeterFig.2 Several factors affecting the accuracy of the flowmeter It is not difficult to see from the principle that the key components affecting the accuracy of the flowmeter are mainly the measuring chamber and the rotor. The machining accuracy of these two components It directly affects the measurement accuracy of the flowmeter after assembly. In the past, our factory used a forming milling cutter to process the rotor, but the result was not good. The symmetry of the processed rotor surface was poor. Therefore, the measurement accuracy has been maintained at level 1.5, which is difficult to improve. Later, all were processed by machining center, which ensured the symmetry of rotor and measuring chamber. In addition, the dynamic balance of the rotor is also a key factor. After each rotor is processed, there are more or less unbalanced quantities, and these unbalanced quantities generally mainly affect the initial flow of the flowmeter, which in turn affects the accuracy of measurement at small flow rates. Spend. The machining accuracy of the synchronous gear affects the measurement accuracy of the flowmeter and the noise during operation. The function of the synchronous gear is to ensure that the two conjugate rotors can maintain a certain gap no matter what angle they turn. The gap between the two rotors varies according to the diameter of the flowmeter. Generally, the small diameter flowmeter is kept at about 0.1mm, and the large diameter is kept at about 0.4mm. The size of the gap directly affects the accuracy of the measurement: the larger the gap, the more gas is lost through the gap, resulting in a decrease in the measurement accuracy of the flowmeter. However, relatively large particulate impurities in the gas can also pass through the gap without affecting the measurement. On the contrary, if the gap is small, the amount of gas lost through the gap will be less, and the measurement accuracy of the flowmeter will increase. The selection of standard parts can also affect the measurement accuracy of the flowmeter. The most important part of the standard parts is the bearing. Our factory mainly uses imported bearings from SKF and NSK. In order to reduce the initial flow of the flowmeter, lift off the dust cover at one end of the bearing and wash out the lubricating grease inside the bearing, because the grease will damp during the rotation of the bearing. During the use of the flowmeter, the bearing is lubricated by splash lubrication, so that the bearing can dissipate heat in time and prolong the service life of the bearing. The above analysis is about the influence of the components of the flowmeter itself on the measurement accuracy of the flowmeter. There are also many other situations that affect the measurement of the flowmeter in the actual use and operation process. There are mainly the following aspects: 1) High-pressure metering and low-pressure gas. It is to install the metering chamber on the high-pressure pipeline, and then adjust the pressure through the pressure regulator. The gas user uses gas on the low-pressure pipeline. When the gas consumption of the low-pressure pipeline user is not large, according to the gas state equation, the temperature is similar. When the small flow of the low-pressure pipeline is inversely calculated to the high-pressure pipeline, the flow will be smaller, and even this flow cannot reach the starting flow of the flowmeter. The flow meter does not count. Therefore, it will cause a large measurement error. 2) Unreasonable pipeline design may cause large measurement errors. Figure 2 is a schematic diagram of the actual pipeline installation, two parallel pipelines, when the main network uses gas, the manual valve of the branch network is closed. The flow meter is normal. When the sub-pipeline is also using gas, the manual valve is opened. Since the gas in the main pipeline is divided by the sub-pipeline, the air pressure in the main pipeline will drop, so that the pressure before the No. 1 flow meter is less than the pressure behind the meter. , the flowmeter is reversed, and the flowmeter also accumulates the flow, resulting in double metering. To avoid this, a check valve must be installed in front of flow meter 1. Figure 2 Pipeline installation diagram 3) Correct installation will help improve the measurement accuracy of the flowmeter and prolong its service life. When the flowmeter is installed on the pipeline, it should be ensured that the threaded holes on the flowmeter body and the threaded holes of the pipeline flange are aligned to ensure the parallelism of the flange, avoid the flowmeter from being subjected to other external forces, and prevent the meter body from being deformed by force, so that the Flowmeter stuck. When opening the flowmeter, the front valve should be opened first, and then the rear valve should be opened slowly to start the flowmeter under pressure, so as to avoid the flowmeter being stuck due to the impact deformation of the rotor of the flowmeter due to the air hammer effect. The above is the whole content of this article. You are welcome to inquire about the flowmeter selection and quotation of our factory. 'The Reasons Affecting the Measurement Accuracy of the Roots Gas Flow Meter'

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