Catalogue 9 - STAUFF Filtration Technology

A www.stauff.com/9/en/#21 21 Multipass Test The Multipass Test evaluates the performance of a filter element. Standardised in ISO 16889-2008, this test allows comparable and repeatable results of the elements performance. If a normal filter element life is between a few weeks up to several months, this test reduces this life down to 90 minutes. The element is subjected to a fluid that a large amount of a special test dust ISO MTD contains. Results are given for the ß-ratio, dirt-hold capacity (DHC) and differential pressure. It is used for designing hydraulic circuits, developing new filter materials and comparison of different filter elements. See also page 18 and page 19 to get more information about the outcome data. In former time this test was also known as the Multipass Test ISO 4572. Nominal Flow Rate The nominal flow rate describes the flow rate or the volumetric flow rate for which the respective filter has been designed. It is usually given in litres per minute (l/min) or US Gallons per minute (US GPM) and is an important parameter in the filter design. Nominal Pressure Pressure for which the filter is designed and which it can be identified with. Operating Pressure / System Pressure Maximum pressure with which the filter may be used. Surface Filter Impurities are separated on the surface of the filter element. Surface filters are designed to have uniform pores (gaps), therefore they can almost completely retain specific particle sizes. Surface filters are made of Metal Wire Mesh or Cellulose materials. Other surface filters are metal-edge filters. Valve Bypass Valve A bypass valve is a valve that is integrated in a filter or filter element and allows the oil to bypass the contaminated filter element if a defined pressure differential is exceeded. Bypass valves are used to protect the filter element. Non-Return Valve It prevents the continuation line from draining while the filter element is changed. Reverse Flow Valve It is used to bypass the filter element for reversible oil flow so that the fluid does not pass through the filter element in the reverse direction. Multi-Function Valve A combination of bypass, reverse flow and non-return valve. Viscosity The viscosity of a fluid describes the flow behavior of a liquid. There are the kinematic viscosity υ with the unit “m²/s” and the dynamic viscosity h with the unit “Ns/m²”. In the field of filtration, in the design of filters the kinematic viscosity is required for calculating. The kinematic viscosity υ can also be calculated with the dynamic viscosity h and density ρ: υ = h ρ The kinematic viscosity unit is “mm²/s”, before it was called centistokes or Stokes (1 cSt = 1 mm²/s = 10 -6 m²/s). The unit of dynamic viscosity is “Ns/m², it was previously reported in Poise (10 P = 1 Ns/m² = 1 Pa s). Filter Material (Continuation) Polyester 100% Polyester Fibres with thermal bonding High pressure differential resistance Good chemical resistance High separation efficiency of the finest particles Tear-proof structure Cellulose Filter material made of Cellulose Fibres with special impregnation Variants with the lowest price with good dirt retention capacity Not suitable for water based media Stainless Fibre Sintered Stainless Fibres with three-dimensional labyrinth structure for depth filtration Low flow resistance with high dirt-hold capacity Excellent chemical and thermal resistance Stainless Mesh Filter elements with a Metal Wire Mesh are often used as a conditionally reusable solution in protection filters, Suction-Line Filters or Return-Line Filters. Depending on the require- ments (micron rating, pressure, dynamics) different types of mesh are used like twill, linen, or also Dutch weave. Wire mesh fabric made of material 1.4301 or 1.4305 for surface filtration (other material on request) Low flow resistance due to large-pored screening surface Excellent chemical and thermal resistance Cleanable under special conditions Flow Rate This is the amount of fluid that flows past a specific cross-section per unit time. It is given in litres per minute (l/min) or gallons per minute (US GPM). Hydraulic Fluid A pressure liquid is defined to be a fluid used in hydraulic and lubrication systems. According to ISO 6743, the fluids are divided into mineral oil based, flame resistant and biodegredable liquids. Micron Rating Regarding micron rating, we must differentiate between the filter materials that are used. To define the micron rating for Inorganic Glass Fibre filter elements, the ß-value as per ISO 16889 is commonly used. Absolute and Nominal micron rating Micron rating is the size of particles which are filtered out by filters at a certain efficiency. When this efficiency is at least 99.5%, we speak about absolute micron rating/filtration. Nominal micron rating is just a commercial trick for all efficiencies lower than 99.5%, meaning that for the same micron rating (for ex. 5 µm) in the case of nominal rating, not all particles will be captured in the filter as in the case of absolute micron rating. Catalogue 9 § Edition 02/2023 Filtration Guideline