Causes Of Failure Of Glass Rotor Flowmeter Caused By Medium
Dec 18, 2021
1. The medium is not full
In daily production, there will occasionally be a partial tube phenomenon. This phenomenon can be regarded as a typical case of liquid containing bubbles. When the electrode level is lower than the medium level, it is ideal to use straight pipes before and after the flowmeter, and the measurement data is relatively stable. However, the gas volume in the upper half of the pipe is also calculated as the medium flow rate, so the measurement error is relatively large in this case; when the electrode level is higher than the medium level, the measurement circuit of the electromagnetic flowmeter is in an open state, and the measured data Seriously distorted. The following methods can be used to deal with the faults caused by the non-full pipe of this medium: try to install the electromagnetic flowmeter on the vertical pipeline flowing from the bottom up; in actual production, the electromagnetic flowmeter needs to be installed horizontally. In this case, it should be installed in the pipeline. The electrode axis of the electromagnetic flowmeter is parallel to the horizon (otherwise the sediment will cover the low electrode); in order to avoid negative pressure in the measuring tube, the sensor of the flowmeter should be installed downstream of the pump for control Upstream of the valve; the installation port of the flowmeter sensor should have a certain back pressure and should be far away from the direct discharge port.
2. Measurement failure occurs when the medium contains air bubbles
The medium inhales gas from the outside or the dissolved gas in the medium transforms into free bubbles are two ways to generate bubble gas in the liquid. If there are large bubbles in the medium, the entire electrode will be covered when the bubbles pass through the electrode, causing the flow signal input loop to open instantaneously, and the output signal will fluctuate. To determine the cause of such fluctuations, you can do this by cutting off the loop current of the magnetic field. If the flowmeter still displays and is still in a fluctuating state after cutting off, it proves that the presence of bubbles in the medium will cause the electromagnetic flowmeter to fluctuate. Use a pointer multimeter to measure the electrode resistance of the electromagnetic flowmeter, and you will find that the loop resistance of the electromagnetic flowmeter electrode is higher than the normal resistance value.
If air enters the measured medium due to the installation position of the electromagnetic flowmeter, if the electromagnetic flowmeter is installed at the high point of the pipe system and the gas is stored, or the flowmeter fluctuates due to the inhalation of air from the outside, the electromagnetic flowmeter needs to be replaced. The location is modified and installed at the lowest point of the pipeline, or installed with a U-shaped pipe. However, in some cases, because the electromagnetic flowmeter has a large caliber or the installation location is not easy to change, it is possible to install an air bag and exhaust valve upstream of the flowmeter to solve this situation.
