What are the types of central pre-filters?

Classified according to how filtering works:

Laminated Filters:
Principle: A large number of micron-sized grooves are engraved on both sides of a thin and specific plastic lamination. When a series of lamination pressures of the same pattern are tightened by springs and liquid pressure on a specially designed inner support, the grooves between the laminations are formed. Cross, thus forming a series of filter units of about 100μm.During filtration, the water passes through the laminations from the outside, the filter laminations are tightly pressed together under the action of the hydraulic forces of the springs, the impurity particles are trapped at the intersection of the laminations, and the filtered water flows out of the filter. In the backwashing state, when a certain pressure difference or time is reached, the system flushes the controller to control the valve to change the direction of the water flow, so that the impurities on the laminations are flushed out.
Disadvantages: Incomplete washing of impurities, uneven filtration accuracy, and no sewage outlet.

Downstream central pre-filter
Principle: Most of them use 50-100μm stainless steel filter screen. The pressure water of tap water penetrates from the inner wall to the outer wall of the pipeline. Impurities such as sediment, rust, red worms, etc. are trapped by the membrane holes. When the flush valve is opened, the impurities trapped by the stainless steel membrane are trapped. The water is washed away, realizing the flushing of the filter element.
Disadvantages: If the water quality is poor, or the consumer’s habits are not good, the filter element is easy to be blocked, not only the small impurities cannot be washed out, but embedded deeper and tighter in the filter element, which is easy to become secondary pollution, and only the shell can be opened. Take out the filter element and brush it with a toothbrush.

Syphon type central pre-filter
Principle: The siphon type central pre-filter adopts an external pressure type, which penetrates from the outer wall of the pipe to the inside through the pressure of tap water, and particles such as sediment, rust, and red worms are trapped on the surface by the membrane holes, and the flushing switch is turned on. The water flows in the filter element. A negative pressure is formed around, and the built-in water distributor can more effectively remove the dirt and impurities trapped on the filter screen. The impurities trapped on the membrane surface are washed away by the water through the inner pipe of the rain cutter. , the flushing effect is much better.
Disadvantages: The product structure is complex and the washing is not thorough. For example, the water quality is relatively poor. Some impurities are embedded deeper and tighter in the filter element. Finally, the filter element is blocked, causing secondary pollution. Once blocked, it is very difficult to maintain. Most siphon products are produced. The filtration precision is above 50μm.

Backwash central pre-filter
Principle: The backwash central pre-filter belongs to the “internal pressure type” under normal working conditions. The pressure of tap water penetrates from the inner wall of the filter to the outer wall, and particulate impurities such as sediment and rust are trapped in the pipe. Open the flushing valve. The impurities trapped by the filter are washed away by the water. If the water quality is poor and the consumer does not wash it for a long time, there is no need to worry if it is blocked. Through the backwash switch, the piston is moved to the lower part, and the direction of the water flow is changed to “external pressure type”.
Compared with the previous products, the backwash central pre-filter has been further improved in technology. The structure is reasonable. The water inlet and outlet can be rotated at will. The installation is convenient. “Forward flushing, recoil flushing” can completely flush out impurities at will, to prevent secondary pollution caused by accumulation of impurities, and the most critical point is that the accuracy can be as low as 5μm, which is also not available in other pre-filters. .

Xi’an CHIWATEC Water Treatment Technology is a high-tech enterprise specialized in various water processing devices. Aside from these individual products, which cover a number of types and series, we can also help with related comprehensive engineering projects. Thanks to our hard work and dedication upon our founding, we are now one of the fastest-developing water treatment equipment manufacturers in Western China.

Further reading:

Underground Reverse Osmosis Plant

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