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.
Electrode material
Corrosion resistance and wear resistance
Stainless steel: 0Crl8Nil2M02Ti is used for industrial water, domestic water, sewage and other weakly corrosive media. It is suitable for petroleum, chemical, steel and other industrial sectors as well as municipal, environmental protection and other fields.
Hastelloy B: has good corrosion resistance to hydrochloric acid at all concentrations below the boiling point, and is also resistant to corrosion by non-chlorinated acids, bases, non-oxidizing salts such as sulfuric acid, phosphoric acid, hydrofluoric acid, and organic acids.
Hastelloy C: resistant to non-oxidizing acids, such as nitric acid, mixed acid, or corrosion of mixed media of chromic acid and sulfuric acid, and also resistant to oxidizing salts such as Fe, ", Cu" or other oxidants, such as Corrosion of hypochlorite solution and seawater above normal temperature
Titanium: It is resistant to seawater, various chlorides and hypochlorites, oxidizing acids (including fuming sulfuric acid), organic acids and alkalis. It is not resistant to the corrosion of relatively pure reducing acids (such as sulfuric acid or hydrochloric acid), but if the acid contains an oxidizing agent (such as nitric acid, Fc++, Cu++), the corrosion is greatly reduced.
钽: Excellent corrosion resistance and glass are very similar. In addition to hydrofluoric acid, fuming sulfuric acid, alkali, it is almost resistant to the corrosion of chemical media (including boiling point of hydrochloric acid, nitric acid and sulfuric acid below 50 ° C). Antimony in alkali; corrosion resistant.
Platinum/titanium alloy
Almost resistant - cut chemical media, but not for aqua regia and ammonium salts.
Stainless steel coated tungsten carbide
For non-corrosive, strong abrasive media.
Note: Due to the wide variety of media, its corrosiveness is affected by complex factors such as temperature, concentration and flow rate, so this table is for reference only. The user should make his own choice according to the actual situation. If necessary, the corrosion resistance test of the material to be selected, such as the coupon test.
Steam vortex flowmeter measurement requirements
Keywords: steam vortex flowmeter, saturated steam vortex flowmeter, superheated steam vortex flowmeter
What should I pay attention to when measuring vortex flowmeter? What is the best way to measure steam installation by vortex flowmeter? Can vortex flowmeters be used for steam metering? The vortex flowmeters are evaluated for their measurement performance under single-phase flow conditions. There is currently no single-phase flowmeter for measuring the system variation of two-phase flow. However, the two-phase flow exists objectively, and its influence on flow measurement is unavoidable. Despite the difficulties, people are still trying to study the mechanism of its influence on flow measurement, and take corresponding countermeasures to improve the accuracy of flow measurement.
First, steam flow measurement difficulties
During long-distance transportation, dry steam will partially condense due to heat loss, resulting in reduced steam dryness and become wet steam. The gas-liquid two-phase flow structure in the horizontal pipe is related to the gas-liquid two-phase volume ratio and the flow velocity. In the steam pipe, since the volume ratio of the condensed water in the wet steam is small, the drain pipe drawn from the bottom of the horizontal pipe is made. , can receive a good hydrophobic effect. When the flow rate is particularly high, it will also behave as a circular flow, that is, there is a liquid film on the pipe wall, and the central part of the pipe is a gas core with droplets. Due to the influence of gravity during horizontal flow, the lower liquid film is higher than the upper pipe. The thickness of the wall, in the vertical ascending pipeline, the basic structure of the gas-liquid two-phase flow has a fine bubble flow structure, a bullet-like flow structure, a block flow structure, a ring-shaped flow structure with fibers, and an annular flow structure.