First of all, the self-cleaning filter has the following types:

Backwash filters are further divided into:

(1) Filter Backwash filter

(2) Backwash the filter with external liquid.

Self-cleaning filters, such as backwashing and mechanical self-cleaning.

Second, the selection of the filtering method of the self-cleaning filter

Different types of self-cleaning filters should be selected according to the characteristics of the material. The backwash filter is suitable for the filtration of viscous liquids. For high viscosity or high solids content, other forms of self-cleaning filters are required. The backwash filter is not suitable.

Third, the main difference between the backwash filter and the filter with self-cleaning filter

1. Different structures:

   The backwash filter consists of a carbon steel barrel, a wedge-shaped stainless steel bar filter, a butterfly valve and a sewage collector. During normal operation, the butterfly valve is opened, the drain is closed, and the fluid flows from the inlet through the filter and then through the outlet. The self-cleaning filter is composed of main components such as drive mechanism, control line (including pressure difference switch), main pipe, filter element assembly, cleaning mechanism and connecting flange.

2. The working principle is different:

   (1) Backwashing filter When the backwashing filter is working, the water flow guide valve is in an open state, and the water flow enters the filter from the inlet, and is filtered through the filter screen and the dirt box at the outlet. The water is blocked by the filter. When the straight-through backwash filter needs to drain, close the water flow guide valve and open the drain valve. The water flows through the filter in the front half of the filter. Part of the water flows into the system after being filtered, and the other part flows from the outside of the filter to the inside. Rinse the inner wall. The dirt on the water is discharged through the sewage outlet, which is used as a reverse automatic flushing filter and removing the dirt. The entire backwashing process does not need to shut down the system or manually clean the filter element to achieve online sewage discharge.

   (2) Backwashing filter When the self-cleaning filter is working, water enters the filter from the water inlet. First, the coarse filter filters out the larger particles of impurities, and then reaches the fine filter screen to filter out the fine particles of impurities through the fine filter. After that, drain the clean water from the water outlet. During the filtration process, the inner layer of fine mesh gradually accumulates, creating a pressure difference between the inside and the outside. When the pressure difference reaches the preset value, the automatic cleaning process will start, and the entire cleaning process will last for tens of seconds. The drain valve is closed at the end of the cleaning, and the increased water pressure returns the hydraulic cylinder piston to its original position, and the filter begins to prepare for the next flushing cycle. During the cleaning process, the normal filtration of the filter will not be interrupted.