Filtration Testing and Development 

Vehicles and equipment frequently encounter contamination that may cause excessive wear, unreliable operation, or complete failure. These harmful contaminants include particulate debris from ingested dust, water, microbiological growth, and lubricating oil soot and wear debris. Filtration products minimize exposure to these contaminants, reducing equipment maintenance costs and downtime.

Southwest Research Institute (SwRI) evaluates filtration performance, solves filtration-related problems, and develops improved filters. With broad capabilities in material sciences, engine design and development, and fuel and lubricant technologies, the Institute provides a significant, single resource to filtration manufacturers, suppliers, and users. Institute staff members participate in professional societies and industry groups that promulgate filtration standards and specifications. Because of its independent and impartial status, SwRI frequently offers opportunities to participate in cooperative research and development programs. Institute technical divisions supporting filtration technology have achieved certification to ISO 9001 or 9002, ensuring compliance with stringent quality control procedures in design, development, and testing.

For more than 25 years, the Institute has conducted oil- and fuel-filter testing, continually improving capabilities, facilities, and equipment. Engineers and scientists use laboratory testing, experimentation, field analysis, and concurrent engineering to address a comprehensive range of filtration-related problems. SwRI’s areas of focus include:

• Fuel and lubricant filtration testing
• Particle counting and surface chemistry evaluation
• Performance and durability assessment
• Filtration test method development
• Field analysis and contamination assessment

Fuel Filtration Tests

Fuel systems continually encounter contaminants that harm fuel-system components, reduce engine performance, and plug fuel filters. Using standardized and custom-designed tests and advanced analytical tools, including a computerized liquid filter bench test facility, engineers evaluate filtration-related problems. Institute staff perform most fuel filtration tests, including:

• SAE J905 and ISO 4020 fuel filter tests
• SAE J1985 fuel filter initial single-pass efficiency test
• SAE J1488 emulsified water removal test
• SAE J1839 coarse water removal test
• ISO TR 13353 diesel fuel filter – initial efficiency by particle counting, retention capacity, and gravimetric efficiency
• SwRI-developed wear index evaluation
• Contaminant chemical and particle size analysis and sensitivity and durability

SwRI scientists and engineers perform standardized tests on a wide variety of fuel filters. This fuel/water separator test stand is used to evaluate the effect of fuel additives on a filter’s ability to remove water from the fuel.

Lubricant Filtration Tests

Stringent automotive and engine emission standards require lubricants to tolerate increased contaminants, such as soot. At the same time, engine manufacturers and vehicle users are demanding reduced maintenance and extended oil drain intervals. To meet both criteria, manufacturers are developing improved lubrication filtration systems to remove more contaminants for a longer time. SwRI provides a wide range of lubricant and hydraulic oil filtration testing and analyses, including:

• ISO 4548-12 multipass lubricating oil filter test
• SAE J1858 full-flow oil filter test
• SAE HS806 oil filter test
• ISO 4572 hydraulic filters – multipass method
• Heavy-duty filter performance specifications, such as Cummins, Caterpillar, and Mack
• Soot and contaminant chemical analysis

While testing filter integrity, the bubble point test also helps measure the pore size of filter elements.

Using an automatic sampling manifold, SwRI runs life and efficiency tests for oil filters.

Particle Counting and Surface Chemistry Evaluation

Filtration design and development require a comprehensive understanding of particle contamination and surface chemistry. Excessive particle contamination contributes to filter plugging, causes excessive engine wear, and develops injection system deposits. Using surface chemistry, SwRI scientists assess the wetting and immersion behavior of liquid and solid material, evaluating the filtration capabilities of innovative filtration media. Institute services include:

• Batch and On-Line Particle Counting
  • Calibration to ISO specification
  • SAE AS 4059 (formerly NAS 1638 method)
  • ISO 4406 method
• K100 Tensiometer
  • Surface tension, including DuNoüy ring and Wilhelmy plate methods
  • Interfacial tension, including DuNoüy ring and drop volume methods
  • Contact angle
  • Surface free energy
  • Adsorption
  • Critical micelle concentration

Using a particle counter and analyzer, SwRI staff members measure the size and number of particulates in a hydraulic fluid sample. Particulates affect the degree of engine wear.

Standardized laboratory tests, such as the Wilhelmy plate (left) and the DuNoüy ring (right) methods, establish the surface and interfacial tension of fluids such as fuels, lubricants, hydraulic fluids, and surfactant-containing fluids.

Performance and Durability Assessment

The Institute performs qualification testing under simulated service conditions to ensure that filtration components and systems meet government and industry standards. To support this testing activity, SwRI engineers design special test facilities and fixtures that simulate expected service conditions. Physical environmental testing may include:

• Shock
• Vibration
• Temperature
• Humidity
• Rain
• Sand and dust
• Fluid compatibility

Institute staff perform a wide variety of environmental evaluations on filters, such as this vibration test. Using industry- and SwRI-developed test protocols, engineers combine contamination, pressure cycle, thermal cycle, and vibration in a single test, providing close to real-world test data in a timely and cost-effective manner.

In the event of component failure, Institute engineers use systematic failure analyses to study the component’s engineering design, specification requirements, material, function, manufacturing sequence, and service environment and loading. SwRI staff members also perform a wide variety of test and evaluations to identify and eliminate the cause of failure. These tests include:

• Macroscopic and microscopic examinations
• Chemical analysis
• Fractographic evaluation
• Analytical modeling
• Corrosion product determination
• Nondestructive evaluations

Filtration Test Method Development

The Institute, working with industry and government agencies, is developing improved test methods that better simulate the fuel and lubricant filter environment. By incorporating real-world operating parameters into test methods, SwRI engineers improve repeatability and reproducibility in the laboratory. Institute staff members have developed several novel filtration-related test methods and analysis techniques, including the SwRI Wear Index fuel filter test and rating method and the ISO test for lubricating-oil soot removal devices.

In an Institute-developed wear index test, engineers evaluate the ability of a filter to remove engine component wear debris under real-world conditions.

Field Analysis and Contamination Assessment

Filters often encounter unknown contaminants that reduce filter life or performance. Engineers use contaminant, filter, and fluid analyses to identify the contaminant, its source, and filter performance. SwRI staff members use a wide variety of analytical tools and test methods, including:

• Scanning electron microscope
• X-ray fluorescence
• Fourier transform infrared analysis
• Microbiological analysis
• Optical microscopy
• Lubricity analysis
• Inductively coupled plasma

Using a scanning electron microscope, SwRI scientists determine the contaminant that plugs a fuel filter. Here, suspected engine wear debris reduces the fuel flow through the filter media, greatly decreasing its efficiency.

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