Daily maintenance of box-type filters

Box-type filters are commonly used solid-liquid separation equipment in industrial production. Regular maintenance is crucial for ensuring their filtration efficiency, extending their service life, and guaranteeing the stable operation of production. The following is the detailed content of the daily maintenance of box-type filters:
I. Pre-operation inspection
Equipment appearance inspection
Check whether the filter housing, filter plates, and filter frames have cracks, deformations, or corrosion. Pay special attention to whether the connection parts (such as flanges and bolts) are loose to avoid leakage during operation.
Check whether the pressure gauge, flowmeter, and other instruments return to zero normally and whether the pointer is flexible to ensure the accuracy of the monitoring data.
Filter material inspection
Confirm whether the filter cloth (or filter paper) is intact, free from damage, holes, or aging, and whether the edges are firmly fixed to the filter plate to prevent solid particles from leaking during filtration.
If a filter element is used, it is necessary to check whether the model of the filter element is correct, whether the installation is in place, and whether the sealing ring is intact.
Inspection of pipelines and valves
Check whether the liquid inlet pipe, liquid outlet pipe, and sewage pipe are unobstructed, and whether there are any signs of blockage or leakage. Whether the valve switch is flexible and whether the handle position is correct (such as the liquid inlet valve is open and the drain valve is closed).
Ii. Monitoring During Operation
Pressure and flow control
Pay close attention to the pressure gauge reading in real time. During normal operation, the pressure should be stable within the designed range (such as 0.1-0.3MPa). If the pressure suddenly rises, it may be due to clogged filter materials or unsmooth pipelines. The machine should be stopped immediately for inspection. If the pressure is too low, it might be due to damage or leakage of the filter material. The cause needs to be investigated.
Observe the flow rate changes. If the flow rate continues to decline, it may be due to excessive accumulation of filter residue on the surface of the filter material. It is necessary to consider backwashing or replacing the filter material.
Temperature and vibration monitoring
For filters handling high-temperature liquids, it is necessary to monitor that the medium temperature does not exceed the equipment's tolerance range (such as the temperature limit of the sealing parts), to prevent the filter material from deforming or the seal from failing due to high temperatures.
Check if there is any abnormal vibration or noise during the operation of the equipment. If so, it may be due to uneven installation of the filter plates, loose bolts, or damage to internal components. The equipment needs to be shut down for maintenance.
Leak investigation
Regularly check whether there is any liquid leakage at the filter plate Spaces, pipeline connections, flange interfaces, and other parts. If leakage is found, tighten the bolts or replace the sealing gasket in time.
Iii. Shutdown Maintenance Operations
Filter residue cleaning
After the machine stops, first open the drain valve to completely drain the residual liquid in the filter, then disassemble the filter plates (or filter cartridges) and remove the filter residue on the surface of the filter material. When cleaning, avoid using sharp tools to scrape the filter cloth to prevent damage to the filter material.
If the filter residue is highly viscous, you can first rinse the filter cloth with clean water or neutral detergent and then dry it with compressed air (note that the pressure should not be too high to prevent damage to the filter cloth).
Filter material cleaning and replacement
Filter cloth cleaning: Select an appropriate cleaning method based on the material of the filter (for example, nylon filter cloth can be soaked in warm water and neutral detergent, while polypropylene filter cloth can withstand mild acid and alkali cleaning). After cleaning, check if the pores of the filter cloth are unobstructed. If hardening, damage, or a significant decrease in filtration efficiency is found, it should be replaced in time.
Filter element replacement: Replace the filter element at the cycle specified in the equipment manual (such as every 500 hours of operation), or force replacement when the pressure difference exceeds the set value (such as 0.1MPa) to prevent deterioration of the filtration effect due to filter element blockage.
Component maintenance
Check whether the sealing surface of the filter plate is flat. If there are scratches or wear, gently sand the area with sandpaper. If the sealing rubber strip ages and loses its elasticity, it needs to be replaced with a new one to ensure a tight seal between the filter plates.
Clean the impurities inside the pressure gauge and flowmeter, calibrate the instrument readings, and ensure the monitoring accuracy.
Four. Periodic in-depth maintenance
Quarterly maintenance
Completely disassemble the filter, inspect the internal components (such as support beams and guide rails) for rust or deformation, and carry out rust removal and anti-corrosion painting treatment on the metal parts.
Test the sealing performance of the valves, lubricate pneumatic or electric valves (such as adding grease), and ensure smooth opening and closing.
Annual maintenance
Replace all seals (such as O-rings and gaskets) to prevent leakage due to aging.
Conduct a pressure resistance test on the filter housing (such as a water pressure test, with a pressure of 1.25 times the design pressure) to check for any weak links and ensure the safety of the equipment.
If corrosive media are dealt with for a long time, it is necessary to check whether the internal anti-corrosion coating is intact. If necessary, re-spray anti-corrosion materials (such as epoxy resin).
V. Handling of Special Circumstances
Long-term shutdown maintenance
If the filter needs to be out of use for more than one month, the internal liquid should be drained completely, the filter material and the housing thoroughly cleaned, and after drying, anti-rust oil should be applied to the surface of the metal parts. The filter cloth should be sealed and stored to prevent moisture and mold.
Close all valves, cut off the power supply, and regularly (such as once a week) check whether the equipment is damp or rusty.
Abnormal fault handling
Filter material damage: If the liquid becomes turbid after filtration, the machine should be stopped immediately to replace the filter material. At the same time, check whether the feed contains hard objects or impurities to prevent further damage to the filter material.
Sealing leakage: If leakage persists after tightening the bolts, it may be due to deformation of the sealing surface or damage to the rubber strip. The components need to be replaced, and the filter plate spacing readjusted.
Vi. Maintenance Records and Safety Regulations
Record management
Establish a maintenance ledger to record in detail the time, content, and problem-solving situation of each inspection, cleaning, and component replacement, which is convenient for tracing the operating status of the equipment and formulating a reasonable maintenance cycle.
Safety Precautions
Before maintenance, the feed source must be cut off and the pressure inside the filter released to ensure that the equipment is in a state of shutdown and pressure relief.
When handling high-temperature and corrosive media, protective gloves, goggles, and other labor protection supplies should be worn to avoid direct contact with the media.
When disassembling the filter plates, the bolts should be loosened step by step in sequence to prevent the filter plates from suddenly popping off and causing injury.
Through the above daily maintenance measures, the operational efficiency of the box-type filter can be effectively enhanced, the downtime due to faults can be reduced, and the service life of the equipment can be prolonged. In actual operation, the maintenance frequency and details should be adjusted in combination with the equipment model, medium characteristics, and production conditions to ensure the pertinence and effectiveness of the maintenance work.