The electromagnetic flowmeter has a large measuring range, usually 20:1~50:1, and the optional flow range is wide; the diameter of the electromagnetic flowmeter is wider than other types of flowmeters, from a few millimeters to 3 meters; the positive and negative two-way flow can be measured. The pulsating flow rate can also be measured as long as the pulsation frequency is much lower than the excitation frequency; the meter output is linear in nature; it is easy to select the material type of the fluid contact member, and can be applied to corrosive fluids and the like. Since the electromagnetic flowmeter measures much more with suspended solids or dirt than other flow meters, the probability of failure of the inner wall adhesion layer is relatively high. If the electrical conductivity of the adhesion layer is close to the liquid conductivity, the instrument can output the signal normally, but only change the flow area to form a hidden fault of the measurement error; if it is a high conductivity adhesion layer, the electromotive force between the electrodes will be short-circuited; if it is an insulating adhesion layer The surface of the electrode is insulated to disconnect the measuring circuit. The latter two phenomena will make the meter inoperable.
Gas turbine flowmeter and screwing vortex flowmeter measurement difference
Keywords: gas turbine flowmeter, Tianxin gas turbine flowmeter, gas gas turbine flowmeter
First, the characteristics of gas turbine flowmeter and spiral vortex flowmeter
Gas turbine flowmeter and screwing vortex flowmeter are the main gas metering instruments in China. In foreign countries, almost no one uses gas to swirl into the vortex flow meter. At present, there are certain applications in the domestic vortex flowmeter. In terms of standard conditions. The international standard ISO9551 promulgated by the International Organization for Standardization and the international recommendations R6, R32 promulgated by the International Organization of Legal Metrology (OIML) have corresponding national standards and regulations in China and developed countries. The above documents guarantee the authority of gas turbine flowmeters in gas metering. Sex. Gas-introducing vortex flowmeters have not yet established relevant standards. It is difficult to guarantee the authority of the flow meter in gas metering. At present, in domestic flow meters for gas measurement, gas turbine flowmeters dominate, and the vortex flowmeters also have a certain market. The use of the two is similar, and users often have doubts about the choice of the two.
Second, choose from the type of flow meter
Various flow meters, such as volumetric flowmeters, speedmeters, and differential pressuremeters, have different characteristics. Different flowmeter types have different turndown ratios. The turbine flowmeter has a turndown ratio of 1:20 to 1:30, the Roots flowmeter has a turndown ratio of 1:20 to 1:160, and the film gauge has a turndown ratio of 1: 160 (The error characteristic curves of these three kinds of flow meters are shown in Figure 1), and the appropriate flow meter should be selected according to the actual situation.
By comparing the error characteristics of the above flowmeters, it can be seen that the starting flow of the membrane meter and the Roots flowmeter is small, the initial flow of the turbine meter is relatively large, and the membrane surface exhibits a positive deviation in the small flow state. The Roots flowmeter exhibits a negative deviation. At low flow rates, the gas supply company is more willing to select a membrane meter for metering.