Types of filters in hydraulic systems

Types of filters in hydraulic systems

According to the filtration precision is divided into: coarse filter and fine filter.

According to the material and structure form of filter element, oil filter can be divided into mesh type, wire gap type, paper filter element type, sintered oil filter and magnetic oil filter.

According to the filtration mode, it can be divided into: surface type, depth type and intermediate type filter.

1、Surface type filter

The surface of the filter element of the surface-type filter is in contact with the hydraulic medium, and this filter material blocks the impurity particles on its surface like a screen.

1）Mesh type filter

   The most common is made of metal wire. It is also a coarse filter.

The filtration precision is low, about 0.08~0.18mm, but the resistance is small, and its pressure loss does not exceed 0.01MPa.

2）Wire gap type filter

  It is also a surface-type filter, which consists of fine metal wires (d=0.4mm) densely wound on a cylindrical support, relying on the gap between the wire spirals to pass through the oil and retain impurities. Installed in the pump suction port, resistance loss of about 0.02MPa, filtration accuracy of about 0.08-0.1mm.

3）Shell-mounted filter

(4) no shell filter, no shell filter, installed in the tank, disassembly and installation is not convenient, but the price is cheap.

2、Depth type filter

In the depth type filter, the oil has to flow through the journey with complex slits to achieve the purpose of filtration.

Filter element materials include: felt, rayon fiber, stainless steel fiber, powder metallurgy material.

Advantages: high filtration precision, up to 0.01-0.006mm, but the resistance loss is larger, 0.03-0.2MPa. So it can't be installed directly in the suction port of the hydraulic pump, and it is installed in the oil discharge or oil return road.

3、Intermediate type filter

Between surface-type filter and depth-type filter.

Such as the use of a certain thickness of microporous filter paper made of filter elements of paper filters. The filtration precision is about 10-20μm, and the high precision can reach about 1μm.

Applicable to general high-pressure hydraulic system, is the current medium and high pressure system is the most widely used fine filter.

In order to increase the filtration area, the filter paper is made into "W" shape.

Direct replacement of filter element, can not be cleaned

The pressure loss is large, about 0.08 ~ 0.35MPa, so it can only be installed in the oil discharge pipe and oil return pipe, and can not be installed on the suction pipe.