Filtrat Terms A

A
ABRASION, FLEX: Cloth wear in a creased area caused by excessive bending, usually associated with cage contact.
ABRASION RESISTANCE: Ability of a fiber or fabric to withstand surface wear.
ABSOLUTE : A degree of filtration that guarantees 100% removal of suspended solids over a specified size.
ABSOLUTE PRESSURE: The pressure above an absolute vacuum. One atmosphere (14.70 psi) greater thar guage pressure. Symbolized as psia when the pressure is in psi units.
ABSORPTION: The taking in, incorporation or reception of gases, liquids, light or heat. Penetration of one substance into the inner structure of another. The process of movement of a drug from the site of application into extracellular compartment of the body.
ACTIVATED CARBON: Charcoal activated by heating to 1472-1652ºF to form a material of high adsorptive gases, vapors, organics, etc. Has a large internal surface area. Removes dissolved color, odor and taste from liquids or gases. Commonly used in the pharmaceutical industry to remove organic contaminants.

ACTIVATED SLUDGE: Biologically active floc from aeration and settling sweage and/or organic matter.
ADSORPTION: The adhesion of a substance to the surface of a solid or liquid. Adsorption is often used to extract pollutants by causing them to be attached to such adsorbents as activated carbon or silica gel.
AEROBIC BACTERIA: Organisms requiring oxygen to live.
AEROSOL: A dispersion of small liquid particles in a gas.

AIR FLOW: Measure of the amount of air that flows through a filter. Commonly expressed in either cubic feet/minute/square foot or liters/minute/square centimeter at a given pressure.

AIR STANDARD: Dry air at 70 degrees F and 29.92" mercury pressure.

AIR-TO-CLOTH (A/C) RATIO: The ratio of gas volume to effective cloth area (sq. ft.).
AMBIENT: Refers to common environmental conditions in which experiment is conducted.
AFFLUENT: Fluid entering the filter or filter system. Commonly described as influent, it is the opposite of effluent.
AGGLOMERATION, PARTICLE: Multiple particles joining or clustering together by surface tension to form large particles, usually held by moisture, static charge or particle architecture.

ALKALINITY: The capacity of water to neutralize acids, a property imparted by the water's content of carbonates, bicarbonates, hydroxides and occasionally borates, silicates and phosphates. It is expressed in milligrams per liter of equivalent calcium carbonate.
ANAEROBIC: Organism capable of growing without the presence of oxygen.

ANGSTROM: A unit of length 10^-10 meter used to express wave lengths. Used in measurements of RO filtration in the ionic range.

ANTISTATIC: A condition inherent in or applied to a material usually fabric or plastic, which results in a significant reduction in or the absence of electrical charges.

ARIZONA ROAD DUST: Standardized test dusts for both liquid and air classified from natural Arizona dust generally referred to an A.C. Fine and A.C. Course Dust. Both dust materials also carry an ISO designation and have a standardized size distribution of particles.

ASHRAE: American Society of Heating, Refrigerating, and Air Conditioning Engineers.
ASYMMETRIC MEMBRANE: A membrane in which the pore size and structure are not the same from one side of the membrane to the other. These membranes are usually considered directional because of difference in flow characteristics depending on which side of the membrane faces the feed stream.

ASME: American Society of Mechanical Engineers. Published code, which governs the design of pressure housings.
AQUEOUS: Similar to or resembling water. Referring to solution made in water.
ASSAY: Analytical procedure to determine purity or concentration of a specific substance in a mixture.

AUGMENTATION: In fabric air filtration, the imposition of an electrical field to the collecting surface and/or subjecting the incoming particulate matter to a charging process.
AUTOCLAVE: A chamber for sterilizing with saturated steam filters or equipment by using constant high temperature and pressure.

B
BACKPRESSURE: A backward surge of pressure from downstream to upstream of the filter. Can be the result of closing a valve or air entrapped in a liquid system.
BACKWASH: Reversal of a fluid flow through the filtration media to remove solids from the filter . . to clean or regenerate a filter.
BACTERIA: Free living simple celled, microscopic organisms having a cell wall, lacking a defined nucleus, shaped . . round, rod-like, spiral or filamentous.
BACTERIAL CHALLENGE: Testing the bacterial retention of a filter.
BAGHOUSE: An air filtration structure utilizing fabric filter bags for the purpose of removing solid particulate from the gas stream . . dust colector.
BAR: Unit of pressure. 1 bar = 14.5 psi.
BETA RATIO: Measurement of filter retention efficiency. Ratio of particles exposed to a filter.
BIOBURDEN: The load or level of microorganisms in a substance to be filtered.
BIOHAZARD: Biological refuse, possibly pathogenic in nature.
BIOSAFETY: Biological safety or non-toxicity of a substance to a living organism. For filters used in health care applications.
BROWNIAN MOTION: The continuous zig-zag motion of suspended minuscule particles. The motion is caused by impact of the molecules in the fluid upon the particles.
BLINDING: Fabric blockage by dust, fume or liquid not being discharged by the cleaning mechanism, results in a reduced gas flow of increased pressure drop across the filter media.
BLOWDOWN: The use of pressure to remove liquids and/or solids from a vessel..
BUBBLE POINT PRESSURE: A test to determine the maximum pore size openings of a filter. The differential gas pressure in which a wetting liquid (water) is pushed out of the largest pores and a steady stream of gas bubbles are emitted from a wetted filter under specific test conditions. A filter integrity test with specified, validated pressure values for specific pore-size and type filters.

C
CAKE: Solids deposited on the filter media.
CATHODE: Negative pole or electrode of an electrolytic system.
CENTRIFUGATION: Separating two substances of differing densities by high speed spinning to create centrifugal force. Generally used to separate suspended particles from liquid.
CHROMATOGRAPHY: Separation of substances in a mixture based on their affinity for certain solvents and solid surfaces.
CLARIFICATION: Clearing a liquid by filtration, by the addition of agents to precipitate solids, or by other means.
CLASS 100 ENVIRONMENT: A room environment maintained by air conditioning and filtration so that fewer than 100 particles of size 1 mm or larger are found in a cubic foot of air.
COATING: Immersion of filter media in a solution to provide the fibers with a coating that will lubricate and thereby reduce self-abrasion.
COLD STERILIZATION: Removal of all bacteria by filtration through a sterilizing grade 0.2mm absolute filter.
COMPATIBILITY: Relation to the non-reactivity of filter materials with a substance to be filtered.
COMPRESSION BAND: Stainless steel band sewn into th end of the bag to provide a surface to clamp against in the baghouse.
CONCENTRATOR: Removes some of the water from a sample to concentrate substances dissolved or suspended in it; usually used to concentrate solutions of biological macromolecules, (proteins & nucleic acids).
CORE YARN: Used in filtration with fiberglass yarn. Spun or texturized yarns are twisted around a filament (core) yarn, adding yarn strength and stability.
CROSSFLOW (TANGENTIAL FLOW) FILTRATION: A filtration system in which the feed stream flows across the filter media and exits as a retentate stream. The retentate stream is recycled to merge into the feed stream, while a portion of it passes through the filter media, resulting in concentration of the feed stream.
CYCLONE: A conical-shaped vessel for separating mixed sized particulates from the gas stream. The vessel has a tangential entry at the largest diameter allowing the larger particles to drop out and be removed from the bottom of the cone while smaller particulate exits overhead with the majority of the gas stream.

D
DIATOMACEOUS EARTH FILTRATION: A filtration method that uses a medium consisting of microscopic shells of single celled plants known as diatoms.
DI WATER: Deionized water; water processed through an ion exchange process by passing through a mixed resin bed to remove positive and negative ions. The purity of water is measured by its electric resistance.
DEAD END FILTRATION: Feed stream flows in one direction only, perpendicular to and through the filter medium to emerge as product or filtrate.
DEPTH FILTRATION: A process that entraps contaminants both within the matrix and on the surface of the filter media.
DIFFERENTIAL PRESSURE: The change in pressure or the pressure drop across a component or device located within the airstream; the difference between static pressure measured at the inlet and outlet of a component device.
DIFFUSIONAL INTERCEPTION: In gas filtration, at low gas flow velocities, tiny particles are subject to Brownian motion, enabling them to move out of the gas streamlines and become intercepted by the filter.
DIFFUSIONAL FLOW TEST: To determine the integrity of a filter. The test is based on the measurement of the diffusional flow of a gas through a wetted filter. Either the gas or the downstream liquid, displaced by the gas, may be measured. The transition from diffusional flow to bulk flow (bubble point) can be determined.
DIRECT INTERCEPTION: Gas filtration: particles larger than the pores are removed by direct contact with the filter surface. Some particles smaller than pores can be removed as well depending on the proportion to their size, of hitting the surface.
DIRT-HOLDING CAPACITY: Amount of dirt or debris retained by a filter in grams per unit area of the filter medium.
DMF: Drug Master File. A written document that explains the formulation of an active ingredient, referenced in an Investigational New Drug (IND), New Drug Application (NDA), or Amendment to New Drug Application (ANDA) from a company.
DOP: Dioctyl phthalate, a plasticizer that can be aerosolized to particles of extremely uniform size. Retention of DOP aerosol is used a s standard procedure for pore size rating of air filters.
DOWNSTREAM SIDE OF FILTER: The filtrate or product stream side of the filter.
DRY HEAT STERILIZATION: Sterilization at or above 356ºF using a convection or forced air oven without moisture; may concurrently depyro-genate if adequate time and elevated temperature are employed.
DRY SCRUBBER: A chemical reaction chamber that neutralizes acids in a gas stream. Two system types: the spray dryer system injects a slurry, whereas dry sorbent injection systems use a dry powder.

Filtration Terminology: E-O P-W