Image Credit: Jaeger Environmental | BakerCorp | Saint-Gobain Plastic Films and Tapes
Filter media is material that actively separates solids from a solution and/or binds select materials in a solution. Base fluids may include coolants, corrosive chemicals, gasoline, diesel fuel, hydraulic fluid, lubricants, water, oil, inks, dies, and paints. Filter media can also remove particulates and contaminants from gas or air.
Filtration grade or Beta ratio is an important specification to consider when selecting filtration media. This micron-rating characterizes a material’s ability to remove contaminants based on particle size.
Water absorption, maximum pressure and maximum liquid flow or maximum gas flow are also important parameters to consider.
Some filtration media is reusable or disposable. Other products meet requirements from regulatory agencies such as the U.S. Food and Drug Administration (FDA).
Types of Filter Media
There are many types of organic filter media:
- Activated carbons are usually made from bituminous coal or lignite and used in wastewater treatment applications. The material source and mode of activation provide specific end-use properties.
- Activated clay is often used to remove dissolved contaminants such as acids, oxidation by-products, and surfactants.
- Diatomaceous Earth (DE) is a naturally-occurring mineral with high absorption, low bulk-density, and high brightness.
- Cellulose is a natural, plant-based filter material with rough fibers that vary in both size and shape. Types of cellulose include cellulose acetate, nitrocellulose or cellulose nitrate, and regenerated cellulose.
- Like cellulose, cotton is a highly-efficient filtration media. Cotton’s irregularly-shaped fibers and strong absorption properties provide strength even under wet conditions.
- Other types of organic filter media include sand and paper.
Hydrocarbon recovery technology. Video Credit: Pentair Separations
Plastic Filter Media
Filter media includes plastics such as polyethersulfone (PES), polypropylene (PP), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyvinylidene chloride (PVDC), and polysulfone (PSU).
- PES is a high-performance polymer that provides excellent resistance water and steam.
- PP is a thermoplastic filter material that can be used in outdoor applications because of its resistance to ultraviolet (UV) light, weathering, and ozone.
- PTFE exhibits a high degree of chemical resistance and is often marketed in proprietary classes of materials such as Teflon? (DuPont Dow Elastomers).
- PVDF filters also provide good chemical resistance, but do not perform well at elevated temperatures.
- PVDC offers low permeability to water vapor and gases while PSU afford good dimensional stability.
- Synthetic filter media also includes non-plastic materials such as glass fiber, glass wool, ceramics, metal, and porous metal.
ASTM D6830 - Standard test methods for characterizing the pressure drop and filtration performance of cleanable filter media
ISO 11057 - Air quality test method for filtration characterization of cleanable filter media
RGS50003 - Qualification test standard - engine oil filter media durability
MIL-P-21386 - Paper, filter media, roll-type
SS-S-448 - Slag and stone, crushed; gravel, crushed and uncrushed (for sewage trickling filter media)
Related Products & Services
Filter elements are used to remove impurities from liquids. They are used in water treatment systems and fluid processing applications.
Gas Dryers, Filters, and Purifiers
Gas dryers, filters and purifiers are designed to remove particulates and purify a gaseous process stream. Gas dryers may be an integral part of a gas filter, or a substantive feature. Gas purifiers can remove gaseous contaminants to levels as low as one-part-per-trillion.
Hydraulic filters are used for handling petroleum-based oils, emulsions, synthetic hydraulic fluids and lubrication oils.