Significant extension of feeding time
Under the same material concentration and feed pressure, the pressure filtration process that could fill the filter chamber in 30 minutes has gradually been extended to over 45 minutes, and the flow rate remains low (such as an initial flow rate of 50m ³/h, which later drops to below 10m ³/h), indicating that the filter cloth pores are blocked by filter cake particles, increasing the filtration resistance and requiring replacement.
Abnormal increase in moisture content of filter cake
The normal moisture content of the filter cake remains stable at 15% -25% (such as alumina filter cake which is about 20%). If the filter cake is pinched into clumps, drips, or the weight of the filter cake increases significantly after unloading (at the same filter chamber volume, the weight exceeds the standard by more than 10%), it indicates that the permeability of the filter cloth has decreased and cannot be effectively dehydrated, and replacement is necessary.
The turbidity of the filtrate increases
Normal filtrate should be clear (such as no obvious suspended solids when processing slurry). If the filtrate appears as milky white, gray, or visible solid particles (which can be observed through the filtrate tank), and after excluding the factor of "sudden increase in feed pressure causing filter cake cracking", it is highly likely that the filter cloth is damaged (such as holes or tears), and the machine needs to be stopped for inspection and replacement of the corresponding filter cloth.
Serious material leakage in the gap between the board and frame
During the feeding process, a "turbid liquid" with solid particles (not a small amount of clear filtrate) continuously seeps out between the plate and frame, and after adjusting the alignment of the plate and frame and tightening the hydraulic pressure, there is still no improvement. It may be due to wear on the edge of the filter cloth and deformation of the sealing surface, which causes the filter cloth to be unable to fit the sealing groove of the filter plate and needs to be replaced.
The surface of the filter cloth shows obvious damage
Check the filter cloth after unloading the cake:
existHoles and tears(Diameter>5mm or length>10mm), even if temporarily repaired with tape, local leakage may occur due to reduced filtering area, requiring direct replacement;
Edge of filter clothSevere wear and tearThe filter cloth in the corresponding area of the sealing groove becomes thinner or fuzzy, or the fixed part between the filter cloth and the filter plate (such as hooks or slots) breaks and cannot be stably fixed, and needs to be replaced.
The surface becomes hard, loses elasticity, and cannot be restored to softness after cleaning (there is a "stiff feeling" when rubbed by hand);
The size of the filter cloth is deformed (such as the side length of the filter cloth shrinking by more than 5%, resulting in the inability to cover the entire filtering surface of the filter plate), or the warp and weft lines of the filter cloth are significantly loose, and the pores are uneven, which needs to be replaced.
After each filter press, the filter cloth will be cleaned (such as high-pressure water gun flushing, alkali washing). If the following situations occur, it indicates that the filter cloth is irreversibly clogged:
After cleaning, there is still a stubborn filter cake layer on the surface of the filter cloth (which cannot be scraped off with a scraper or appears as a hard shell after drying);
After cleaning, if there is no significant improvement in filtration efficiency during the next use (the feeding time and filtrate turbidity are still abnormal), it indicates that the pores of the filter cloth have been blocked by fine particles and need to be replaced.