The Design and Elements of Hydraulic Filters

The fluid used in hydraulic devices can gather a lot of contaminants over time and need to be removed. They can be removed in many different methods, for example by trapping pollutants with devices better known as a filter. The contaminants in the fluid have the ability of damaging the hydraulic device itself and thus require to be filtered.

Hydraulic filter design:

Hydraulic filter design

  • The hydraulic filters are designed to combat the contaminants in the hydraulic fluid and thus need to be very efficient and installed with precision. They need to have a certain mechanical strength and a guarantee that they can work in high pressure.
  • The overall structure of the filters needs to be kept as simple as possible since the process of the replacement of the filters needs to be as simple as possible as well.
  • The filters are designed such that they prevent the contaminants from damaging the mechanical parts of the hydraulic system. The filters are typically rated in microns. (micron is short for micro-meter).
  • The filters issued in factories usually are around 10 microns. It is important to note that the lower the micron numbers the finer and more effective is the filter.
  • Besides having a micron rating that is to do with the particle size, filters also have a burst rating.
  • The burst rating can be defined as the amount of pressure the filter can take before it gets deformed; because if it does get pushed too hard it will get deformed and be of no use.
  • Filters are also designed with a flow rating; which is defined by the amount of liquid that the filter can process over a given period of time. The design of the filers is such that the more they remove the slower the flow will be.
  • It would be ideal to select a filter with a high flow rate or a flow rate which is efficient and makes sure that it is able to keep up with the pressure and speed of the rest of the system.

Hydraulic filter elements:

1. Wedge-Wire


Wedge wire is a profiled wire which is usually made from stainless steel. It is available in segments, curved and flat panels, baskets and cylindrical form also called slot tube. It is usually low maintenance and you have the advantage of using it in either low or high pressure.

2. Sintered Powdered Metal

Sintered Powdered Metal

These are useful where highly permeable and inexpensive filters are required. They are available in many different shapes like cylindrical, conical cylindrical, close at one end of the cylinder, round , square and rectangle.

3. String Wound

String Wound

String wound filter cartridge are usually stringed by 100% food grade Polypropylene thread symmetrically. In general this filter cartridge will not contain any wetting agents, solvents, binders or anti static agents. The function of this is similar to the PP sediment filter, which also happens to be steadier.

Hydraulic filter benefits:

  • It extends the machine life by removing contaminants from the oil.
  • Placing filtering media in the pressure line provides a great deal of protection for components located immediately downstream. In addition to which the off line filtration enables continuous, multi pass filtration at a controlled flow velocity and pressure drop. This in turn increases the filtering efficiency.

on 6 February, 2014