Which Filtration screens should be used for hydraulic fluids

Hydraulic fluids: Fluid is essential in transmitting energy, power in a circuit in addition to working providing required lubrication, security and cooling of the application surface. The most common types of fluids are:

Mineral oils- oil derived fluids

Fire resistant: They have intrinsic properties of resisting fire

Synthetic fluids: Enhanced chemical products to receive enhanced features

Ecological fluids: Synthetic fluids with high biodegradability

Choice of a fluid for a hydraulic system should be made on considering various factors which severely affect the function of a hydraulic system such as delay in controls, pump corrosion, extensive absorption, excessive temperature rise, efficiency loss, high wear, block or air absorption in the system.

Properties to be considered for choosing a hydraulic fluid are:

  1. Dynamic viscosity: It shows the fluid’s resistance to sliding caused by the impact of particles which cause it.
  2. Cinematic viscosity: it is a common factor in the hydraulic application. It is based on the ratio of dynamic viscosity and fluid density. It varies with the change in temperature and pressure
  3. Viscosity index: it determines the potential to cross the filter materials. Fluid with low VI can cause early clogging of the filter.
  4. Service temperature: Service temperature significantly impacts the basic properties of a fluid. As stated above, cinematic viscosity of a fluid varies with change in temperature.
  5. Heat transfer: It is the property that shows the potential of hydraulic oil to transfer heat among the surface and cool them.

Effect of fluid contamination on hydraulic components:

Solid contamination is the main cause of poor function, damage and early closure of the hydraulic systems. It cannot be eliminated completely, but it is feasible to control fluid contamination by Inconel wire mesh screens. Solid contamination primarily causes damage to surface and component wear.

Surface abrasion: It results into leakage through seals, affects system functionality and causes failures.

Surface erosion: Leakage through seals, affect component performance and variation in adjustment of control component and damage

Adhesion of moving components: damage due to loss of lubrication

Fatigue: Damage of components due to fatigue

Use of filtration technology for contamination control

Surface filtration is performed through direct use of screens. Inconel mesh screens are used in the filter equipments to prevent larger particles from entering in the system. These filters are usually made with metal mesh screens. The woven mesh screens are made in different shapes and sizes to trap the particles when they find smaller apertures than their size.

Depth filters are made with high strength nickel alloys mesh screens for use in inorganic fiber filtration. These screens increase the overall performance of the filters to hold the contaminants. The efficiency of filter is stated as the maximum particle size than can flow through the mesh of the filtering grid. The efficiency of woven mesh screens is well proven and tested. Mesh screen with good filtration stability enhances the life of filter. They can be used with any nature and properties of hydraulic fluids to prevent the contamination. Therefore, hydraulic component engineers understanding the contamination problem, always recommend the use of appropriate filters.