Multi media filter is a device that achieves water purification by combining multiple layers of different filter materials, and its core working principle is based on physical interception and adsorption. The following is a detailed analysis of its working principle:

1. Filtering process:

When the system is in a filtered state, unfiltered water passes through a three-layer water distributor, coupled with a specially designed casing, to reach the packing layer inside the filter in a nearly laminar state. When water flows through the packing layer, impurities are trapped within the packing layer. The mushroom shaped filter collector at the bottom of the filter evenly collects and flows out the filtered water. Advection filtration determines that the filter can filter at high flow rates and still achieve good filtration results.

2. Backwash process:

As impurities accumulate in the packing layer, the head loss will continue to increase. When the head loss reaches a certain set limit, or after a pre-set period of time, the system will automatically switch to backwash mode to clean the accumulated impurities.

For the system, regular backwashing is necessary to remove accumulated impurities. When the system is in backwash mode, a certain filter will simultaneously reflux clean, filtered water into the filter through a three-way backwash valve. In this reverse flow process, the packing layer of the backwashed filter unit is washed up by the impact of water flow, and impurities are discharged through a three-way backwash port. In the filtration system, a specially designed water collector creates an inner loop flow in the packing layer during backwashing, where the packing materials rub against each other to maximize backwashing efficiency, reduce the required backwashing water, and prevent sand from running during backwashing. When the backwash is completed, the valve returns to the filtering state, and the next filter is ready to enter the backwash state.