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Electromagnetic flowmeter common faults - flow measurement values do not match actual values

Electromagnetic flowmeters are now a very type of flow meter in the industry. The flow rate is measured according to the Faraday's law of electromagnetic induction. The electromagnetic flowmeter is composed of two parts: an electromagnetic sensor and an electromagnetic flow converter. The sensor is composed of a plurality of parts: a measuring tube, an electrode, an exciting coil, a core and a yoke housing.

Electromagnetic flowmeters are mainly used to measure the volumetric flow of conductive liquids and slurries in closed pipes, including highly corrosive liquids such as acid-base salts. The wide application of electromagnetic flowmeters, such as petroleum, chemical, metallurgy, textile, food, pharmaceutical, paper, environmental protection, etc., may also occur during the operation of electromagnetic flowmeters. This fault is generally divided into two categories: One is the failure of the meter itself, that is to say the failure caused by the structural parts or components of the electromagnetic flowmeter; the second is caused by external causes, such as improper installation, sedimentary structure and so on.

The measurement of the flowmeter must be accurate, and the precise flow rate can better manage the production. The following mainly describes the reasons and solutions for the inconsistency between the measured value of the electromagnetic flowmeter and the actual value.

1. Cause analysis

(1) Whether the transmitter circuit board is in good condition;
(2) When the liquid flow rate is too low, the liquid to be tested contains tiny bubbles, and the bubble rises gradually gathers above the pipe, and the flow area of the liquid changes. When the gas is too much, an interference signal is generated, which affects the measurement accuracy;
(3) The signal cable is not well connected or the insulation performance of the cable is reduced during use, resulting in inaccurate measurement;
(4) The parameter setting value of the converter is not accurate.

2. Solution
(1) Check if the transmitter circuit board is intact. If the junction box is ingress or corroded by corrosive liquids, electrical performance may be degraded or damaged. The board should be replaced at this time.
(2) Ensure that the flow rate of the liquid to be measured in the pipeline is above the minimum flow limit to enable the transmitter to work properly.
(3) Check the signal cable connection and the insulation performance of the cable. If the signal cable is loose, reconnect it. If it is checked that the insulation of the cable does not meet the insulation requirements, you need to replace the cable.
(4) Re-set the converter set value and check the zero and full scale values of the converter.

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