Shengshi Runhe Front Filter Proportional Fertilizer 3 Stack Filter Gravel Filter, also known as quartz sand filter, sand filter. It is a filter that forms a sand bed by homogenizing equal particle size quartz sand as a filter carrier for three-dimensional deep filtration, and is commonly used for primary filtration. It mainly uses gravel as filter material for filtration. Gravel filter is one of the media filters, its sand bed is three-dimensional filtration, has a strong ability to intercept dirt. It is suitable for deep well water filtration, agricultural water treatment, front pretreatment of various water treatment processes, etc., and can be used in various places such as factories, rural areas, hotels, schools, gardening farms, water plants, etc. Of all filters, it is effective to treat organic and inorganic impurities in water with a gravel filter, which has a strong ability to filter out and retain impurities, and provides an uninterrupted water supply. As long as the organic matter content in the water exceeds 10mg/L, a gravel filter should be used regardless of the inorganic content. During normal operation, the water to be filtered reaches the medium layer through the water inlet. At this time, most of the pollutants are trapped on the upper surface of the medium, and the dirt and other floating organic matter are trapped inside the medium layer to ensure that the production is free from pollutants and can work well. When the pressure difference reaches the set value, the electronic control PLC will send to the three-way hydraulic control valve in control, and the three-way hydraulic control valve will automatically control the three-way valve of its corresponding filter unit through the waterway, so that it closes the inlet channel and opens the sewage channel at the same time, due to the sewage discharge channel. Under the action of water pressure, the water of the other filtering unit passes through the mouth of the filtering unit and flushes the medium layer of the filter unit, so that the effect of cleaning the medium is achieved. The AIGER sand filter can also be controlled by timing to discharge sewage. When the time reaches the time set by the timer controller, the electric control box sends out sewage discharge cleaning to the three-way hydraulic control valve, and the specific sewage is discharged as above. 02