Product Details

1、 The flow rate, full flow rate, limitations, and diameter of seawater remote electromagnetic flowmeter:

The selected instrument diameter varies depending on the flow rate, just like the pipe diameter. The flow rate of low viscosity liquids such as process industry guaranteed water and pipelines is generally an economic flow rate of 1.5-3m/s. The flowmeter is used on such pipelines, and the sensor diameter should be the same as the pipe diameter. When the flow meter is at full capacity, the liquid flow velocity can be selected within the range of 1-10m/s, which is relatively wide. The upper limit flow rate is theoretically unrestricted, but it is recommended not to exceed 5m/s unless the lining material can accept the erosion of liquid flow rate. In practice, it is rare to exceed 7m/s, and it is even rarer to exceed 10m/s. The lower limit of flow velocity for full flow rate is generally 1m/s, while some models of instruments have a flow rate of 0.5m/s. In the early stages of operation of some new construction projects, if the flow rate is low or in a pipeline system with low flow velocity, from the perspective of measurement accuracy, the instrument diameter should be changed to be smaller than the pipe diameter and connected with a reducer. For fluids with substances that are prone to adhesion, accumulation, scaling, etc., the selected flow rate should not be less than 2m/s, preferably increased to 3-4m/s or above, to achieve self-cleaning and prevent adhesion and accumulation. For highly abrasive fluids such as slurry, the commonly used flow rate should be below 2-3m/s to reduce wear on the lining and electrodes. When measuring low conductivity liquids close to the threshold, it is advisable to choose a lower flow rate (less than 0.5-1m/s) as much as possible. As the flow rate increases, activity noise will be added, resulting in a shaky output. The limitations of flow meters are relatively large, with a range of no less than 20. Instruments with active range switching function can exceed 50-100. The caliber of standardized products that can be supplied domestically ranges from 10mm to 3000mm. Although small and medium-sized calibers are still commonly used in practice, they are different from most other flow meters. Compared to volumetric, turbine, vortex street, or Coriolis mass instruments, large-diameter instruments have a greater proportion. Among nearly 10000 instruments of a certain enterprise, the identification of small caliber below 50mm, medium caliber between 65-250mm, large caliber between 300-900mm, and super large caliber above 1000mm accounts for 37%, 45%, 15%, and 3%, respectively.

2、 Liquid conductivity of seawater remote electromagnetic flowmeter:

The prerequisite for using seawater remote electromagnetic flowmeter is that the measured liquid must be conductive and cannot be lower than the threshold (i.e. lower limit). If the conductivity is below the threshold, measurement errors will occur until it cannot be used. Even if it changes beyond the threshold, it can still be measured, and the change in indication error is not significant. The threshold of a universal flowmeter is between 10-4 (5 × 10-6) S/cm, depending on the model. When used, it also depends on the length of the flow signal line between the sensor and the converter, as well as its scattered capacitance. The manufacturer uses the signal line length corresponding to the standard conductivity in the order. Instruments with non-contact capacitive coupling large-area electrodes can measure liquids with conductivity as low as 5 × 10-8)/cm. The conductivity of industrial water and its aqueous solutions is greater than 10-4S/cm, and the conductivity of acid, alkali, and salt solutions is between 10-4 and 10-1S/cm. There is no problem with their use, and the conductivity of low distilled water is also 101S/cm. Petroleum products and organic solvents with low conductivity cannot be used. The above figure lists the conductivity of several liquids. From the materials, it was found that some pure liquids or aqueous solutions have low conductivity and are considered unsuitable for use. However, in practical tasks, there may be instances where they can be used due to the presence of impurities, which are beneficial for adding conductivity. Regarding aqueous solutions, the conductivity of the material is measured in the laboratory for pure water ratio. In practical applications, aqueous solutions can be proportioned with industrial water, resulting in higher conductivity and facilitating flow measurement. There is also a type of liquid that cannot be measured by flow meters installed on pipelines in the absence of existing conductivity data. Sampling from the on-site pipeline offline to measure its conductivity using an indoor conductivity meter is considered usable. This is because during the offline sampling process, the measured liquid has already differed from that in the pipeline; For example, the liquid has received CO2 or N0x from the atmosphere to generate trace amounts of carbonic acid or nitric acid, which alters its conductivity. Based on practical experience, it is recommended that the conductivity of the liquid used in practice be at least one order of magnitude higher than the threshold set by the instrument manufacturer's regulations. Due to the fact that the lower limit of the manufacturing plant's instrument standard rules is the lowest measurable value under various application conditions, it is subject to some application conditions such as conductivity averaging, connection with signal lines, external noise, etc. Otherwise, it may present output shaking phenomena. We have repeatedly encountered situations where measuring low alcohol distilled water or deionized water requires its conductivity to be close to the threshold of 5 × 10-6S/cm, resulting in output jitter during use.

3、 Schematic diagram of seawater remote transmission electromagnetic flowmeter:

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