Dropper type gas flow measuring device and method based on weighing principle

Abstract

The invention provides a dropper type gas flow measuring device and method based on a weighing principle. The dropper type gas flow measuring device comprises an electronic scale, an oil storage tank, a dropper, a dropper support, a gas inlet valve, a fine adjustment valve, a three-way tube and a computer, wherein the oil storage tank storing oil is arranged on the electronic scale, a lower-end dropper orifice of the dropper installed on the dropper support is located under the oil liquid level, an upper-end dropper orifice of the dropper is communicated with the gas inlet valve and the fine adjustment valve through the three-way tube, and the fine adjustment valve is communicated with a measured object. The electronic scale is connected with the computer, and weigh data and the time for the measuring process are recorded and stored through the computer. The dropper type gas flow measuring method comprises the steps that the gas inlet valve is turned on; the fine adjustment valve is adjusted to enable gas flow passing through the fine adjustment valve to meet the gas inlet requirements of the measured object; an initial weigh reading is recorded; the gas inlet valve is turned off; gas flow measurement continues, a plurality of continuous time points are recorded in real time, meanwhile weigh readings corresponding to the time points are recorded; when the computer judges that measurement is needed to stop, the gas inlet valve is turned on, and the measurement process is finished; outflow gas flow is calculated.

Description

technical field [0001] The invention belongs to the technical field of instrumentation and vacuum testing, and in particular relates to a dropper-type gas flow measuring device and method based on a weighing principle. Background technique [0002] Vacuum pumps have been widely used in industrial fields such as machinery, electronics, metallurgy, nuclear energy, and space simulation, as well as scientific and technological research, and play an important role in the development of modern science and technology and the construction of the national economy. [0003] The pumping rate of the vacuum pump is usually used as its model identification, and the pumping rate is also the most critical technical index of the vacuum pump, and the measurement of the pumping rate is also a must-test item for the factory inspection and index determination of the vacuum pump. national and international standards. For example: "GB / T19955.1-2005 Vapor Flow Vacuum Performance Measurement Method...

AI Technical Summary

Problems solved by technology

[0007] ① There are too many manual operations, resulting in large measurement errors;

[0009] In the Chinese patent No. ZL200910012545.3, although it is proposed to use a photoelectric liquid level switch instead of manual visual inspection to judge the time when the liquid level reaches the set height, however, due to the fact that the installation position of the liquid level switch is not suitable for adjustment Limitations, when measuring the pumping rate of the vacuum pump under different pressures, it is difficult to ensure that the measurement time interval is exactly in a high-precision state, and it is difficult to operate when changing the dropper with different diameters, and often brings new changes in the setting height of the liquid level switch error

[0010] ②It can only measure the average gas flow rate within the timing interval, and cannot reflect the instantaneous change of gas flow rate during this period;

[0011] The calculation obtained by the measurement formula is only the average gas flow rate in the time interval of the secondary reading, so it cannot reflect the instantaneous change of the gas flow rate in this time period

Due to the above reasons, before measuring the pumping rate at each pressure point of the vacuum pump, it needs to be maintained for a long enough time to ensure that the pressure in the standard test hood reaches a stable balance, resulting in low measurement efficiency

For the change of gas flow rate caused by the decrease of gas pressure in the dropper, it can only be ignored as a principle error

[0012] ③The transparent glass dropper used has original measurement error;

[0013] First of all, the inner diameter of the glass tube for making the dropper cannot be strictly processed to ensure its dimensional consistency, and the volume indication can only be calibrated by drawing the scale line, resulting in limited reading accuracy

Secondly, when measuring the small gas flow rate, the small-diameter dropper used has serious capillary phenomenon, which has a large amount of depression for the increase of the liquid level, resulting in an error that cannot be quantitatively estimated

[0014] Due to the above shortcomings of the traditional vacuum dropper type gas flow measurement device and method, it has brought great inconvenience to the vacuum industry. The vacuum industry urgently needs a new gas flow measurement device and method, which can be convenient, fast, accurate and reliable. The measurement of gas flow, especially the measurement of small gas flow

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