Most of the electrical contacts used in water level electrodes are aluminum oxide insulated electrodes. It uses an alumina porcelain tube as the electrode edge material, which has the advantages of temperature and pressure resistance, easy to use and install, but it also has the shortcomings of being unable to withstand sudden temperature changes and the impact of large mechanical forces, such as cracking and fragile. Therefore, pay attention to the following issues during installation and use:
1. The electrode has two installation forms: threaded and press-in. It is best to clean the electrode seat thread of the water level measuring cylinder before installation. If possible, use tap (for press-in) and die (threaded) to process it. Then install the electrode to avoid deformation of the hole seat of the electrode threaded hole or ash impurities, because it is a troublesome thing to screw the thread. When installing, use a qualified wrench to tighten, and the force should be appropriate. The sealed red copper gasket must be annealed to make it easy to deform to achieve a better sealing effect.
2. For daily maintenance and replacement of the electrode, it is best to do it when the temperature of the measuring cylinder is low to avoid damage to the water level electrode due to thermal shock. It is also best to preheat or heat it together with the equipment in use when it is put into use.
3. The wiring of the water-level electrode must use the porcelain terminal with the electrode, and the wiring must be reliable. It is best to pour in on the copper wire to prevent the oxidation of the copper wire from increasing the contact resistance.
4. Regularly check the insulation performance of the water level electrode. When checking, the water vapor in the water level measuring cylinder should be drained. Use a megohmmeter to measure the insulation resistance of each electrode to the measuring cylinder. When the insulation resistance of the electrode is less than 1MΩ, it should be Replace the electrode. Should all replaced electrodes be scrapped? Some electrodes can be reused after repairing because some electrodes have a low insulation resistance due to the adhesion of a layer of scale on the aluminum oxide insulating layer. They are soaked in water and their insulation resistance is very low. Dry them in an electric oven or dry them naturally. Sandpaper removes the scale attached to the aluminum oxide insulation layer, and its insulation resistance meets the requirements.
5. Corrosion problems should be considered for the measuring cylinder and electrode. Take boiler steam drum water as an example. To prevent scaling, trisodium phosphate is usually added to the boiler soft water treatment. The measuring cylinder should be drained once a week. The vapor of the gas phase tube should be used to flush the measuring cylinder and electrode. As long as there are conditions, the electrodes in the lower part of the measuring tape should be removed for inspection, and those with severe corrosion should be replaced in time. Drain the water in the measuring cylinder when the production is stopped.