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How to measure the volume of unstable gas

How to measure the volume of unstable gas: When the measured fluid is a gas, the situation is more complicated. Because the gas temperature expansion coefficient is large, it is easy to be compressed, and when the state is far from the standard state, the compression coefficient correction is also required. There are many types of calibration, and there are many types of standard tables. For direct mass flowmeters, the values are not affected by the fluid state, while other types of meters must be compensated for fluid temperature, pressure, and compression factor. . The position requirements of the pressure measuring points are also very different. For example, the vortex flowmeter is required to be installed on the pipeline several times the diameter of the flow sensor; the orifice flowmeter is required to be installed at the positive end of the throttle device; other principles Flowmeters, most of which are required to be installed on the upstream piping of the flowmeter. Therefore, how to deal with the measured data of the calibration and standard tables, according to the corresponding instrument manual, after obtaining the indication values of the calibration table and the standard table, calculate the calibration error according to the formula (6.15).
c. Things to be aware of when using the standard method. When the on-site flowmeter is calibrated by the standard meter method, since the branch flowmeter and the standard flowmeter are installed on the same pipe, and the distance between them is very close, the two tables are easily affected by each other, causing an increase in error, even can not work. For example, when using a Coriolis mass flowmeter to calibrate a Coriolis mass flowmeter in the field, both gauges are fixed by the bracket. If the vibration of the two gauges is difficult to eliminate, two The sections are connected by a length of flexible pipe.
When using a rotary volumetric flowmeter as a standard meter to calibrate a vortex flowmeter, etc., attention should be paid to the influence of the flow artery motion that may be caused by the operation of the rotary volumetric flowmeter on the calibration.
In the volumetric flowmeter, the elliptical gear type, the lumbar wheel type, the rotary piston type, etc., due to the characteristics of its working principle, will cause a certain amplitude of flow artery motion during operation. Figure 6.17 shows the literature [10]. The angular velocity of the elliptical gear flowmeter and the lumbar wheel flowmeter changes. The change of angular velocity induces flow artery motion, which acts on a meter with very sensitive flow artery such as vortex flowmeter, resulting in a significantly higher indication value. One way to solve this problem is to avoid the use of the elliptical gear flowmeter (6=0.3), which is easy to cause flow artery motion, and to add a damper between the two tables, as described in Section 6.1.3 of this chapter. Said.

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