Ten key points to note when maintaining instruments and meters

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　　The maintenance of instruments and meters is not only crucial for the proper operation of devices such as electromagnetic flowmeters, pressure gauges, pressure transmitters, and magnetic level gauges, but it also plays a vital role in the daily production activities of organizations that use these instruments in industries such as electricity, petroleum, and chemicals. Below are ten key points to keep in mind when carrying out the maintenance of instruments and meters: 1. The maintenance work must be carried out by professional instrument engineers. 　　2. When using the ohm meter function of a multimeter, be sure not to take measurements while the device is powered on. 　　3. When using a logic probe or oscilloscope to detect signals, be careful not to let the probes make contact with two measurement pins at the same time, as this essentially creates a short circuit while power is applied. 　　4. When testing the filter capacitors in the power supply, short-circuit the positive and negative terminals of the electrolytic capacitor first. Do not use the test lead wires as a substitute for wires to discharge the capacitor during this process, as this can easily cause the wire core to burn out. A 220V, 60–100W lamp with a bulb lead can be used, connected across the capacitor; the bulb will flash at the moment of discharge. 　　5. When troubleshooting instrument faults in humid environments, it is essential to use a multimeter to check whether the various points on the printed circuit are conductive, as the main issue in such situations is copper foil corrosion. 　　6. When servicing the internal circuits of instruments, if the contacts of the components and the circuit board are coated with insulating varnish, a regular sewing needle can be soldered to the probes of a multimeter in order to pierce through the varnish layer and measure the parameters at various points, thereby avoiding the need to remove a large area of the varnish layer. 　　7. Do not plug or unplug various control boards and plugs while they are powered on. Because when the power is on, plugging in or removing the control board generates a strong induced electromotive force; at this time the instantaneous reverse voltage is very high, which can easily damage the corresponding control board and plug. 　　8. When maintaining instruments such as vortex flow meters, do not strike or touch them randomly, to avoid exacerbating the fault and making it worse over time. 　　9. When removing or adjusting instruments, their original positions should be recorded for restoration. 　　10. When repairing precision instruments, if small parts are accidentally sent flying, one should first determine where they might have fallen; there’s no need to search around randomly. Magnet scanning and visual scanning can be used to locate them. 　　Flow metering is one of the components of measurement science and technology, and it is closely related to the national economy, national defense construction, and scientific research. Doing this job well plays an important role in ensuring product quality, improving production efficiency, and promoting the development of science and technology. Especially in today’s era of energy crises and increasing automation in industrial production, the significance and role of flow meters in the national economy have become even more evident.