MP Filtri Maximum filtration efficiency


“At MP Filtri’s R&D Center in Pessano con Bornago (MI), research projects focused on the study and development of high-tech solutions are always in progress. The latest development is the introduction of a new pleating machine in the prototyping line, entirely dedicated to the study of the pleating/filtering baffle process”.


In order to ensure the ongoing effectiveness of hydraulic fluids, the Milan-based manufacturer constructs its filter elements using specialist materials developed and tested in its R&D Centre Contamination can be broken into three main categories: solid, liquid and solid particles. Most hydraulic system failures are caused by particle contamination. Increasingly advanced hydraulic systems are being designed with ever smalle tolerances, making the presence of solid particles in lubricating and hydraulic fluids problematic. Similarly, the presence of gas, albeit in minute quantities, encourages the formation of additional solid fragments generated by the implosion of air bubbles (or ‘micro-bubbles’) at points in the system where large pressure changes occur. The heat generated by these ‘micro-implosions’ can reach up to 2,000 °C locally. Lastly, contamination by liquid ingress poses a danger to the physio-chemical properties of the lubricating fluid such as viscosity, filterability and hygroscopicity, (i.e., the ability to absorb water) breaking up the lubricating film and/or causing the formation of water vapor or ice.

One of the main sources of contamination is the introduction of hydraulic fluid into the system:
Although new – the standards of cleanliness depend on the manufacturer and may not meet acceptable levels. Tanks with traces of solvents, water, fuels or non-homogeneous liquids may be used and the tanks may contain residues from assembly work (welding, threading, etc.).

Fig. 1 Mobile filtration units

In order to prevent initial contamination of the working fluid, decanting and topping up is carried out via mobile filter units (Fig. 1) equipped with correctly dimensioned and selected filter elements.
In order to guarantee the correct functioning of the hydraulic fluid (lubricating power, thermal conductivity, incompressibility), it is necessary to maintain both contamination control and the stability
of its formulation. In particular, degradation of the oil due to its use under harsh operating conditions leads to the generation of carbon compounds, varnish and, in the most extreme cases, partial degradation of the additive package. To ensure an economically acceptable service life of the hydraulic fluid, it is absolutely essential to use filtration systems with optimised filter materials.

MP Filtri’s solutions
MP Filtri manufactures its filter elements using specialist materials developed and tested at its R&D Centre in Pessano con Bornago (near Milan).

Fig. 2 Filtration performance of the MP Filtri filter element range. Filtration Beta Ratio βx(c) vs. particle size

Each component of a hydraulic circuit is characterised by a sensitivity to contamination due to the minimum (or critical) tolerances of the mechanical seals and/ or between the moving parts. For each individual component, manufacturers usually provide indications of the maximum permissible contamination level in accordance with industry standards (one of the most widely adopted is ISO 4406). Figure 2 shows the filtration efficiency expressed through the filtration ratio (Beta ratio βx(c)) for the entire range of MP Filtri filter elements. Thanks to a close working relationship with its suppliers and the technologies available at its R&D Centre, MP Filtri has developed a wide range of filter elements suitable for a variety of applications, ranging from very demanding cleanliness levels b(3 μm) to solutions optimised in terms of hydraulic system energy losses (pressure or pressure drop).

They always guarantee high-performance filtration (Beta ratio βx(c) ≥ 1000) up to 25μm(c) (Fig. 2).
A unique feature of MP Filtri’s filter elements, compared to other competitors, is that its filtration grades indicated by alphanumeric codes (A06, A10, A16) refer to the respective filtration performance (e.g. 6μm(c), 10μm(c), 16μm(c)) with a Beta ratio βx(c) equal to or greater than 1,000, corresponding to a filtration efficiency of 99.9%.

Fig. 3 Filtration performance vs. test time of Multipass ISO 16889 for MP Filtri filter elements (blue curves) and competitors (green and orange curves). 3A: Beta filtration ratio. 3B: Filtration efficiency

The Beta ratio is the ratio between the number (concentration) of particles entering the filter and the number (concentration) of particles leaving the filter greater than the reference size, for example, β10(c) ≥1000 means that after passing through a filter a concentration of 1,000 particles ≥ 10μm(c) will become 1 particle ≥ 10μm(c). Another distinctive feature of MP Filtri filter elements is the stability of filtration performance throughout the filter’s operating time. Chart 3 shows the filtration ratio Beta βx(c) (Fig. 3A) and the filtration efficiency (Fig. 3B) at 10μm(c) over the duration of the Multipass ISO 16889 test. During filter operation, the filtration performance deteriorates because of the increased pressure drop due to clogging. From the graphs it can be seen that MP
Filtri elements (blue curve), compared to competitor products (green and orange curves), do not undergo significant decreases in filtration performance. ‘An added value of MP Filtri elements is the stability of filtration performance throughout the filter’s operating time’

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