Selection of Electromagnetic Water Meter

Electromagnetic water meter are widely used in the measurement of various conductive media, such as clean water, sewage, liquid acid, alkali, salt, liquid organic chemical products, soy sauce, vinegar and wine in the food industry, etc. Applesauce mixed with lumpy pulp and concrete mixed with sand and gravel, these slurry mixtures can also be measured, but various highly corrosive media need to be equipped with corrosion-resistant engineering materials, such as rubber, polytetrafluoroethylene, etc. as the lining of the flowmeter. Sauces mixed with bubbles and solid substances require special calculation methods to reduce measurement errors.

The Following Factors Should be Considered when using Electromagnetic Water Meter:

(1) Consider the conductivity of the fluid. The minimum conductivity required should refer to the manufacturer's recommendations. Generally, the conductivity is required to be 5 to 20μS/cm; the minimum conductivity that ARTang can provide is 2μS/cm.

(2) The choice of lining material, generally there are several optional materials such as PTFE, PFA, ceramics and rubber.

①PTFE is the most commonly used lining material. Because it cannot be pasted on the inside of the shell, it is not suitable for vacuum conditions. At the same time, some liquids can penetrate PTFE, causing short circuits and corrosion to flowmeter components;

②PFA, which has lower permeability than PTFE, but is easily deformed when temperature and pressure change;

③Ceramic, which is suitable for a variety of application conditions, but this material is sensitive to temperature fluctuations and pipe stress;

④Rubber, neoprene or natural rubber is the cheapest lining, mainly used for water measurement;

(3) When selecting the electrode material of the electromagnetic water meter, not only the corrosion resistance to the measured medium should be considered, but also the avoidance of electrode surface effect should be considered.

Installation Requirements

(1) The electromagnetic water meter can be installed at any position of the pipeline that meets the straight pipe section requirements, but the measuring pipe of the flowmeter must be full;

(2) The electrode axis is horizontal to prevent the electrode from being contaminated and to prevent the loss of measurement signals due to the accumulation of bubbles;

(3) Pay attention to the manufacturer's requirements and install the grounding (grounding ring) of the flowmeter;

(4) Avoid being close to large conductive surfaces such as metal supports;

(5) For relatively rough liquids, the inlet liner of the flowmeter is easily damaged;

(6) Use PTFE lining. When tightening the process connection bolts, follow the torque requirements required by the manufacturer;

(7) To prevent damage to the liner, metal spiral wound gaskets cannot be used. Graphite gaskets cannot be used because they are conductive and may affect the measurement effect;

(8) Electromagnetic water meter are not sensitive to evenly distributed low-content gases. When the fluid contains a large amount of gas, the flowmeter reading will be falsely high. Bubbles accumulated near the electrode will cause measurement problems. When the liquid contains gas, the flowmeter should be installed on a vertical pipeline. In general, the minimum flow rate required is 0.3-0.5 m/sec. If the requirements are not precise, the maximum flow rate cannot exceed 3.5 m/sec.