Laboratory Filters Specifications

Help with Laboratory Filters specifications:

Filter Type

	Filter Type:
	Your choices are...
	Filter Paper		A porous unsized paper used especially for filtering.
	Membrane Filter		A continuous polymeric matrix with channels of defined size. A filtration membrane is a thin, polymeric film made up of thousands of microscopic pores. The size of these pores determines the size rating of the membrane. Membranes can be used in the quantitative separation or filtration of suspended matter from liquids and gases.
	Centrifuge Filter		Centrifugal devices are ideal for small-scale laboratory separations such as protein or nucleic acid desalting and concentration, or separation of labeled molecules from unincorporated label. These devices rely on centrifugal force to drive liquid through the membrane. Increasing the g force (centrifuge speed) increases trans-membrane pressure. Membrane fouling is minimized by design features that result in the g force reaching the membrane at an angle and sweeping accumulated molecules off the surface.
	Syringe Filter		A filter element and housing assembly for use in applications where a sample must be filtered before entering a syringe.
	Pre-Filter		Pre-filters are traditionally depth filters placed upstream from a membrane filter to significantly reduce the particulate loading in the system and thereby allow the membrane to operate efficiently at a light particulate loading.
	Other		Capsules, Air Monitoring Cassettes, Funnels, or any other unlisted, proprietary or specialized laboratory filter.
	Search Logic:		All products with ANY of the selected attributes will be returned as matches. Leaving all boxes unchecked will not limit the search criteria for this question; products with all attribute options will be returned as matches.

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Environment

	Operating Temperature:		This is the full required range of ambient operating temperature.
	Search Logic:		User may specify either, both, or neither of the limits in a "From - To" range; when both are specified, matching products will cover entire range. Products returned as matches will meet all specified criteria.

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Configuration

	Configuration:
	Your choices are...
	Filter Element & Housing Assembly		The porous device which performs the actual process of filtration with the ported enclosure that directs the flow of fluid through the filter element.
	Filter Element Only		The porous device which performs the actual process of filtration.
	Housing Only		A ported enclosure that directs the flow of fluid through the filter element.
	Search Logic:		All products with ANY of the selected attributes will be returned as matches. Leaving all boxes unchecked will not limit the search criteria for this question; products with all attribute options will be returned as matches.

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Sample Type

	Sample Type:
	Your choices are...
	Liquid		A liquid is a substance that does flows and takes on the shape of the container it is in. The particles in a liquid are not as closely bound together as they are when the substance is in the solid state.
	Solid		A solid substance does not flow (like a liquid does) and does not take on the shape of the container in which it is being kept (again, like liquids do). If a solid is heated, it will become a liquid once it reaches its melting point.
	Gas		Gas is the name for a physical state in which substances can exist - at which time they are called gasses. Gas molecules spread out in the atmosphere more than molecules in a liquid or solid state, and therefore gasses are said to have a lower density than solids or liquids.
	Search Logic:		All products with ANY of the selected attributes will be returned as matches. Leaving all boxes unchecked will not limit the search criteria for this question; products with all attribute options will be returned as matches.

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Filter Paper Measurement Type

	Filter Paper Measurement Type:
	Your choices are...
	Qualitative		Qualitative filter papers have a higher ash content that quantitative filter papers. For use in qualitative analytical techniques to determine and identify materials rather than quantify them.
	Quantitative		Quantitative filter papers are acid washed to reduce their ash content. They are ten times lower in ash content than qualitative filter papers.
	Search Logic:		All products with ANY of the selected attributes will be returned as matches. Leaving all boxes unchecked will not limit the search criteria for this question; products with all attribute options will be returned as matches.

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Filter Medium Material

	Filter Medium Material:
	Your choices are...
	Cellulose		A filter material made from plant fibers. Because cellulose is a natural material, its fibers are rough in texture and vary in size and shape. Compared to synthetic media, these characteristics create a higher restriction to the flow of fluids.
	Cellulose - Acetate		Cellulose acetate membranes are not compatible with organic solvents. They are well suited for aqueous solutions. Recommended for use with proteins and protein-related samples.
	Cellulose - Regenerated		Regenerated cellulose membranes are low in protein binding and have low levels of extractables, while maintaining high chemical resistance. An ideal choice for HPLC sample preparation, as well as filtration of aqueous biological samples and organic solvents.
	Cellulose - Nitrate		Also called nitrocellulose, a mixture of nitric esters of cellulose, and a highly flammable compound that is the main ingredient of modern gunpowder. Nitrocellulose is a fluffy white substance that retains some of the fibrous structure of untreated cellulose. It is not stable to heat, and even carefully prepared samples will ignite on brief heating to more than about 150º C (300º F). When nitrocellulose decomposes, it forms products that catalyze further decomposition; this reaction, if not stopped in time, results in an explosion.
	Teflon®		Teflon membranes are compatible with all solvents, acids and bases, and have no extractables.
	Nylon		Nylon, comprising several grades of polyamides, is a general purpose material in wide use; it is tough and resistant and has good pressure ratings. Nylon membranes are compatible with most solvents, both organic and aqueous. Use with strong acids, 70% ethanol, methylene chloride. DMF is not recommended
	Polytetrafluoroethelene (PTFE)		PTFE is an insoluble compound that exhibits a high degree of chemical resistance and a low coefficient of friction. It is sometimes marketed in proprietary classes of materials such as Teflon®.
	Polyvinylidene Fluoride (PVDF)		PVDF is a melt processable fluropolymer. It is similar in properties to other fluropolymers, but has better strength and lower creep than the other members of this family. PVDF has good wear resistance, and excellent chemical resistance. But does not perform well at elevated temperatures. Brand names include: Kynar (Elf AtoChem).
	Polyvinylidene Chloride (PVDC)		Vinylidene chloride (chemical formula CH2=CCl2, polymer repeating unit structure -[CH2-CCl2-]) can be made directly from ethylene and chlorine or by the further chlorination of vinyl chloride with subsequent removal of hydrogen chloride by alkali treatment. It is polymerized in suspension or emulsion processes, using free-radical initiators. The outstanding property of vinylidene chloride is its low permeability to water vapor and gases--a property that makes it ideal for food packaging. Copolymers of vinylidene chloride and other monomers are also marketed. The best known is saran<sup>TM<sup>, a trade name for a copolymer consisting of about 87 percent vinylidene chloride and 13 percent vinyl chloride. Saran<sup>TM<sup> is extruded into transparent films for use as a food wrap.  Saran<sup>TM<sup> is a trademark of the Dow Chemical Company.
	Polypropylene (PP)		Polypropylene is a thermoplastic material exhibiting excellent cold flow, bi-axial strength, and yield elongation properties. It is similar to PVC but can be used in exposed applications because of its resistance to UV, weathering, and ozone.
	Polysulfone		Polysulfone, also known as PSU, has been mass-produced since 1965. It is a thermoplastic polycondensate, used in electric connectors. General properties include the capability to electroplate, and has high strength, good toughness, good dielectric strength, and dimensional stability. It is sold under the trade name Ultrason.
	Polyethersulfone (PES)		Poly(ether sulfones) PES for short, are high performance polymers. Poly(ether sulfones) act a lot like polycarbonates, but they are much more heat resistant. Poly(ether sulfones) also can stand up well to water and steam, so they're used to make things like cookware and medical products that need to be sterilized between uses.
	Ceramic		Materials made of nonmetallic minerals, such as clay, that have been permanently hardened by firing at a high temperature. Most ceramics resist heat and chemicals.
	Carbon		The applications for carbon are many and include its use as an alloying element with iron in the manufacture of steel, its use as brushes in electrical generators and motors, the use of colloidal graphite or carbon to coat surfaces (e.g. glass), in electrical assemblies to absorb microwaves and inhibit photoelectrons and secondary electrons, and the use of high purity carbon (graphite) in nuclear reactors to moderate neutrons.
	Glass Fiber		Glass Fiber is an inorganic fiber that is completely incombustible. It has a high tensile strength in relation to weight and dimensional stability. It does not stretch or shrink. It will not absorb water, rot, mildew, deteriorate or decay.
	Other		Any unlisted, proprietary or specialized material.
	Search Logic:		All products with ANY of the selected attributes will be returned as matches. Leaving all boxes unchecked will not limit the search criteria for this question; products with all attribute options will be returned as matches.

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Housing Material

	Housing Material:
	Your choices are...
	Acrylic		A group of thermoplastics that are transparent and highly decorative. Polyacrylics, or acrylic plastics, are polymers (and copolymers) of derivatives of acrylic acid, H2CCH-COOH. The best known acrylic plastic, sold under the trade names Plexiglas and Lucite, is polymethyl methacrylate. It takes a high polish, is clear and colorless, and is transparent to visible and ultraviolet light. Since it is a thermoplastic, it can be shaped while hot to form a number of objects, such as windshields for airplanes and transparent ornamental objects. Other esters of acrylic acid and methylacrylic acid similarly polymerize and copolymerize to transparent thermoplastics, differing somewhat in hardness and in softening temperatures.
	Acrylic - Modified		Modified Acrylic housings are suitable only for aqueous based samples, they are not compatible with any solvent content.
	Polypropylene (PP)		Polypropylene is a thermoplastic material exhibiting excellent cold flow, bi-axial strength, and yield elongation properties. It is similar to PVC but can be used in exposed applications because of its resistance to UV, weathering, and ozone.
	Other		Any unlisted, proprietary or specialized material.
	Search Logic:		All products with ANY of the selected attributes will be returned as matches. Leaving all boxes unchecked will not limit the search criteria for this question; products with all attribute options will be returned as matches.

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Physical Specifications

	Filter Shape:
	Your choices are...
	Disc (Circular)		The filter element has a circular shape.
	Sheet (Rectangular)		The filter element has a rectangular shape.
	Search Logic:		All products with ANY of the selected attributes will be returned as matches. Leaving all boxes unchecked will not limit the search criteria for this question; products with all attribute options will be returned as matches.
	Sample Size:		Maximum sample size that the filter can accept. This is relevant for centrifuge and syringe filters.
	Search Logic:		All matching products will have a value greater than or equal to the specified value.
	Pore Size:		The pore size at which a particle of defined size will be retained with an efficiency below 100% (typically 90-98%). Rating methods differ widely between manufacturers
	Search Logic:		All matching products will have a value greater than or equal to the specified value.
	Filtration Area:		Filter media and devices are available in a wide range of sizes with different Effective Filtration Areas (EFA). EFA is the filter area that is available for filtration ­ the larger the filter area, the faster the flow rate at a given pressure differential and the larger the expected filter throughput volume prior to clogging for a given solution.
	Search Logic:		All matching products will have a value greater than or equal to the specified value.

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Performance Specifications

	Particle Retention:		The particle size that will be retained by a filter, usually expressed in microns.
	Search Logic:		All matching products will have a value greater than or equal to the specified value.
	Flow Rate:		Determines the volume of liquid that will flow through the filter at a fixed pressure and temperature.
	Search Logic:		All matching products will have a value greater than or equal to the specified value.
	Porosity:		The percentage of the volume of the filter which is empty space.
	Search Logic:		All matching products will have a value greater than or equal to the specified value.
	Hold Up Volume:		The maximum volume of sample that will be held up behind the filter.
	Search Logic:		All matching products will have a value greater than or equal to the specified value.
	Pressure:		The maximum (vacuum) pressure which is recommended for the filter by the manufacturer.
	Search Logic:		User may specify either, both, or neither of the limits in a "From - To" range; when both are specified, matching products will cover entire range. Products returned as matches will meet all specified criteria.

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Features

	Folded (Pre-pleated)?		Pre-pleating has several advantages over unfolded paper. Savings in time required to quadrant-fold circles to fit conical filter funnels in repetitive or multiple analysis; Decreased overall filtration time because of the extra surface area exposed; the normal slow down of filtration speed due to the loading of particulate is postponed; Increased total loading capacity because more filter area is available; Maintained flow rate because of the reduction in filter paper contact with funnel side and the self-supporting shape of the filter itself; The pre-pleating does not significantly affect any of the technical data.
	Search Logic:		"Required" and "Must Not Have" criteria limit returned matches as specified. Products with optional attributes will be returned for either choice.
	Reusable?		Can be reused. Not disposable.
	Search Logic:		"Required" and "Must Not Have" criteria limit returned matches as specified. Products with optional attributes will be returned for either choice.
	Wet Strengthened?		Wet strength is an important feature of filter papers, the strength of the fibers can be compromised when exposed to moisture. Resins may be added to increase the strength of the paper when wet.
	Search Logic:		"Required" and "Must Not Have" criteria limit returned matches as specified. Products with optional attributes will be returned for either choice.
	Sterile?		Free from living organisms and especially micro-organisms. Usually used in food and medical applications.
	Search Logic:		"Required" and "Must Not Have" criteria limit returned matches as specified. Products with optional attributes will be returned for either choice.
	Pre-Filter Included?		Often samples will clog filters prematurely and multiple filters may be needed to process single batches, increasing the costs of filtration.
	Search Logic:		"Required" and "Must Not Have" criteria limit returned matches as specified. Products with optional attributes will be returned for either choice.

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