Thread Content
This post was last edited by Shaanxi Sonic Electronics on 2025-12-4 at 10:51. Due to their high-frequency properties, 80GHz radar level gauges generally have small antenna sizes, which makes them highly sensitive to crystallization or contamination on the antenna surface. Even a thin layer of dirt can cause severe signal attenuation, inaccurate measurements, or even complete failure. Cleaning antenna crystals or contaminants must be done following principles of safety and caution. Below are the detailed cleaning steps and precautions. Step 1: Safety preparation and isolation – this is the most crucial step, ensuring the safety of personnel and equipment. Safety approval and supervision: Before entering the site, ensure that the necessary safety procedures for work (such as work permits) have been completed. If the instrument is installed in a confined space or hazardous area, a supervisor must be assigned. Process isolation: Confirm with the process operators to isolate the equipment or tank in which the level gauge is located. Close the inlet and outlet valves to ensure that the level gauge is no longer exposed to process pressure. Power off: Be sure to cut off the power supply to the radar level gauge (24VDC or 220VAC). It is best to perform power shutdown and Lockout/Tagout (LOTO) both in the control room and at the site itself, to prevent accidental operations. Cooling and pressure relief: If the process medium is at high temperature, it is necessary to wait until the level gauge and its connecting components have cooled down to room temperature. For pressurized equipment, ensure that the pressure has been completely released. Personal protection: Wear appropriate personal protective equipment depending on the properties of the process medium. Step 2: Disassembly and inspection – Remove the gauge: Use appropriate tools to carefully remove the radar level gauge from its mounting bracket. Be careful to protect the process interface and threads. Initial inspection: Move the level gauge to a well-ventilated, well-lit, and safe area. Carefully observe the contamination on the antenna surface to determine the type of contaminant: Crystals: usually white salts, polymers, or crystallizations of process media. Adhesives: such as oil stains, silt, gels, etc. Coating: A firmly attached layer formed in certain processes. Step 3: Select the cleaning method and carry out the cleaning. Choose the mildest and most effective cleaning method depending on the nature of the pollutants. The core principle is to protect the PTFE (polytetrafluoroethylene) or PFA (perfluoroalkoxyalkane) coating on the antenna surface. Once this coating is scratched, the antenna is highly susceptible to corrosion, leading to permanent damage to the instrument. Method 1: Rinse with clean/warm water and wipe with a soft cloth (recommended as the preferred method) – suitable for most water-soluble crystals or ordinary dust. Gently rinse the surface of the antenna with pure water or warm water (below 60°C). Let the water soak and soften the crystals thoroughly; do not scrape hard. Gently wipe it with a lint-free soft cloth (such as lens cloth or suede) or a soft brush (such as a paintbrush). When wiping, the direction should be parallel to the antenna axis, avoiding circular movements to prevent the formation of circular marks that could affect the signal. Method 2: Cleaning with a neutral detergent or a mild solvent is suitable for oil stains, sticky substances, or organic materials that are difficult to remove with plain water. Selecting a solvent: A mild aqueous solution of a neutral detergent is the preferred choice. If it is ineffective, isopropanol (IPA) can be considered. The use of highly corrosive solvents such as **, benzene, strong acids, strong bases, and chlorinated hydrocarbons (such as trichloroethylene) is strictly prohibited, as they will dissolve or damage the antenna coating. Test: If you are unsure whether the solvent is safe, you can first drop a small amount of it in an unimportant area on the edge of the antenna to test it. Cleaning: Dampen a soft cloth with a small amount of the selected solvent and gently wipe the surface of the antenna. Be gentle to prevent the solvent from entering the interior of the instrument or the seams. Method 3: Low-pressure steam or hot water jetting is suitable for tough polymers or heavy oil stains. Use a low-pressure steam or high-temperature hot water gun, maintaining a safe distance, to soften the contaminants. This method carries certain risks; it is necessary to ensure that steam does not penetrate through the cable entries or seams of the instrument housing, which could cause the internal components to become damp or damaged. Not recommended unless necessary. Step 4: Clean and thoroughly dry after processing: After cleaning, wipe the antenna dry with a clean lint-free cloth, then place it in a well-ventilated area to air dry for at least 30 minutes, ensuring that both the antenna and its seams are completely dry. It is strictly prohibited to use compressed air for direct cleaning, as the moisture and oil contained in compressed air can contaminate the antenna, and the strong airflow may damage the internal components. Inspect the sealing surfaces: Check the sealing surfaces of the instrument mounting base (such as O-rings and gaskets). If they are aged or damaged, they must be replaced. Reinstallation: Follow the reverse order of disassembly to carefully reinstall the level gauge onto its mounting base, ensuring a good seal and appropriate torque to avoid damaging the threads by over-tightening. Power and process restoration: Restore power to the instruments, slowly open the upstream and downstream valves, and restore the process conditions. Step 5: Verification and debugging – Check the signal strength: In the device control system, view the echo curve or signal strength of the level gauge (usually expressed in %dB). A clean antenna should be able to detect a very strong and clear first wave (surface echo), with the signal strength being significantly higher than before cleaning. Verify the liquid level value: Compare the reading from the radar level gauge with the liquid level values from other reliable sources (such as manual measurements or other instruments) to ensure accurate measurement. Parameter optimization: If necessary, parameters such as false echo suppression within the instrument can be fine-tuned based on the new echo curve. Important precautions: It is strictly forbidden to use any hard objects for scraping, including screwdrivers, blades, wire brushes, sandpaper, etc. The use of corrosive chemicals is strictly prohibited: protecting the antenna coating is of utmost importance. Handle with care: The antenna is the “heart” of the instrument – it is highly precise and fragile. Thoroughly dry: Any remaining moisture can affect the transmission of high-frequency signals. Prevention first: For conditions prone to crystallization, the following preventive measures can be considered: select models equipped with antenna mirror heating or air purge functions. Regular preventive maintenance cleaning should be carried out to prevent excessive accumulation of crystalline deposits. By following the steps above, the antenna of the 80GHz radar level gauge can be cleaned safely and effectively, restoring its accurate measurement performance. If the instrument still does not function properly after cleaning, it is possible that the antenna has been irreparably damaged; in such a case, it is necessary to contact the manufacturer or a professional technician for repair or replacement.