Glossary of Terms

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ABSOLUTE HUMIDITY:
Actual measurement of water vapor in the air.

ABSOLUTE PRESSURE:
The pressure above an absolute vacuum. One atmosphere (14.70 psi) greater than gauge pressure. Symbolized as psia when the pressure is expressed in psi units.

ABSORPTION:
(gen) The taking in, incorporation or reception of gases, liquids, light or heat. (phys/chem.) Penetration of one substance into the inner structure of another (cf. adsorption, in which one substance is attracted and held on the surface of another). Occurs between a gas or vapor and a liquid. (pharm.) The process of movement of a drug from the site of application into the extracellular compartment of the body.

ACID:
Any substance that donates a proton (H+) when dissolved in a solution. In water treatment, it usually means circulating water with a pH of less than 7.0. Sulfuric acid is the most common acid used to control cooing water pH.

ACTIVATED CARBON:
Charcoal activated by heating to 800-900ºC to form a material of high adsorptive capacity for many gases, vapors, organics, etc. Has a large internal surface area (approx 1,000 m2/g). Commonly used in the pharmaceutical industry to remove organic contaminants. Can be used either as an additive in granular form which is then filtered out or as a filter media in a filtration device itself.

ADSORPTION:
Retention of gas, liquid or solid on a surface due to positive interaction (attraction) between the surface and the molecules of the adsorbed material.

AERATION:
Blowing or mixing of air through water to sweep out other dissolved gases and to equilibrate the water with primarily nitrogen, oxygen and carbon dioxide.

AEROBE:
An organism that grows only in the presence of free (molecular) oxygen.

AEROBIC BACTERIA:
Organisms which require oxygen to live.

AEROSOL:
A dispersion of small liquid particles in a gas.

AIR CLEANING:
An IAQ control strategy to remove various airborne particulates and/or gases from the air. The three types of air cleaning most commonly used are particulate filtration, electrostatic precipitation, and gas sorption.

AIR EXCHANGE RATE:
The rate at which outside air replaces indoor air in a space. Expressed in one of two ways: the number of changes of outside air per unit of time air changes per hour (ACH); or the rate at which a volume of outside air enters per unit of time – cubic feet per minute (cfm).

ALGAE:
A low form of plant life containing chlorophyll that generally requires sunlight and air for existence. Many are microscopic but under favorable conditions can grow sufficiently dense to plug cooling tower distributors on the decks and to interfere with water splashing in the fill. Large masses often slough off the tower and plug heat exchangers or deposit in piping.

ALGAECIDE:
A toxic material that will kill algae. Some of the more commonly used algaecide are chlorine, copper sulfate and phenolic compounds.

ALKALINITY:
An expression of the total basic anions (hydroxyl groups) that is present in a solution. It also represents, particularly in water analysis, the bicarbonate, carbonate, hydroxyl and occasionally the borate, silicate, and phosphate salts which will react with water to produce acid neutralizable anions.

AMBIENT:
Refers to "common" environmental conditions in which experiment is conducted. For example: 14.7 psia and 20º to 25ºC (room temperature).

AMBIENT DEW POINT:
The ambient temperature in degrees Fahrenheit when dew begins to be deposited.

AMBIENT WET-BULB TEMPERATURE:
The wet-bulb temperature that is measured in accordance with the definition of ambient. Readings are obtained by means of a mechanically aspirated psychrometer.

AMMONIA:
A Water-soluble, colorless, pungent gas with the formula NH3.

AMMONIUM:
Positive ion with the formula NH4+ that forms when ammonia dissolves in water. It adds non-natural alkalinity to the water.

ANAEROBIC:
Organism capable of growing without the presence of oxygen.

ANAEROBE (FACULTATIVE):
An organism that can grow under either aerobic or anaerobic conditions.

ANAEROBE (STRICT):
An organism that grows only in the absence of free oxygen (e.g., sulfate reducing bacteria).

ANISOTROPIC (ASYMMETRIC) MEMBRANE:
A membrane in which the pore size and structure are not the same from one side of the membrane to the other. Such membranes are usually considered "directional" because of the difference in flow characteristics depending on which side of the membrane faces the feed stream.

ANODE:
Positive pore or electrode of an electrolytic system.

ANTIMICROBIAL:
Agent that kills microbial growth. See “disinfectant”, “sanitizer”, and “sterilizer”.

AQUEOUS:
Similar to or resembling water. In reference to solution made in water.

ASEPTIC:
Refers to an operation performed in a sterile environment designed to prevent contamination through introduction of bacteria.

ASSAY:
Analytical procedure to determine purity or concentration of a specific substance in a mixture.

AUTOCLAVE(ING):
A chamber for sterilizing with saturated steam filters or equipment by using constant high temperature and pressure (121ºC, 15 psi). One method of ("terminal") sterilization using saturated steam.

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, as an attempt to clean or "regenerate" a filter.

BACTERIA:
Free living simple celled, microscopic organisms having a cell wall and characteristic shape (e.g., round, rod-like, spiral or filamentous); lack a defined nucleus.

BACTERIAL CHALLENGE:
Term used when testing the bacterial retention of a filter.

BAR:
A unit of pressure. One bar = 14.5 psi.

BETA RATIO:
Measurement of filter retention efficiency. Ratio of particles exposed to a filter (as feed stream) to particles present in the filtrate.

BICARBONATE ALKALINITY:
In a water solution, the presence of ions resulting from the hydrolysis of carbonates when these salts react with water. A strong base and a weak acid are produced and the solution is alkaline. Its formula is HCO3-, but its concentration is usually denoted as ppm as CaCO3.

BIOBURDEN:
The load or level of microorganisms in a substance to be filtered.

BIOCIDE:
A chemical that is designed to control the population of troublesome microbes by killing them.

BIOHAZARD:
Biological refuse, possibly pathogenic in nature.

BIOLOGICAL CONTAMINANTS:
Agents derived from, or that are, living organisms (e.g., viruses, bacteria, fungi, and mammal and bird antigens) that can be inhaled and can cause many types of health effects including allergic reactions, respiratory disorders, hypersensitivity diseases, and infectious diseases. Also referred to as “microbiologicals” or “microbials”.

BIOLOGICAL DEPOSIT:
Water-formed deposits of organisms or their waste products (example: slimes, barnacles, etc.).

BIOSAFETY:
Biological safety or non-toxicity of a substance to a living organism by passing tests as listed in the United States Pharmocopeia. Analogous to "chemically inert." For filters used in biological and health care application, Plastic Class-VI tests apply, which include Systemic Injection, Intracutaneous and Implantation Tests.

BLOWDOWN:
Water discharged from the system to control concentration of salts or other impurities in the circulating water.

BLOW OUT:
Water that is blown or pulled out of the air inlet by wind.

BROWNIAN MOTION:
The continuous zig-zag motion of suspended minuscule particles. The motion is caused by impact of the molecules of the fluid upon the particles.

BTU:
British Thermal Units. The amount of heat it takes to raise one pound of water one degree Fahrenheit. The higher the BTU rating, the larger the heating capacity of the furnace or air conditioner.

BUBBLE POINT PRESSURE:
A test to determine the maximum pore size openings of a filter. The differential gas pressure at which a wetting liquid (usually water) is pushed out of the largest pores and a steady stream of gas bubbles is emitted from a wetted filter under specific test conditions. Used as filter integrity test with specific, validated, pressure values for specific pore-size (and type) filters.

BUILDING ENVELOPE:
Elements of the building, including all external building materials, windows, and walls, that enclose the internal space.

BUNA-N:
A Nitrile rubber seal compound. This is a generic term covering many formulations.

CAKE:
Solids deposited on the filter media.

CARBONATE HARDNESS:
Hardness in water caused by bicarbonates of calcium and magnesium. If alkalinity exceeds total hardness, all hardness is carbonate hardness; if hardness exceeds alkalinity, the carbonate hardness equals the alkalinity.

CATHODE:
Negative pole or electrode of an electrolytic system.

CEILING PLENUM:
Space below the flooring and above the suspended ceiling that accommodates the mechanical and electrical equipment and that is used as part of the air distribution system. The space is kept under negative pressure.

CELL:
The smallest tower subdivision which can function as an independent unit with regard to air and water flow; it is bounded by exterior walls or partitions. Each cell may have one or more fans or stacks and one or more distribution systems.

CENTIPOISE (cP):
(N s/m2; N = Newton) A unit of absolute viscosity. One centipoises equals 0.01 stoke.

CENTISTOKE (cSt):
A unit of kinematic viscosity (m2/s). One centistokes equals 0.01 stoke.

CENTRIFUGATION:
Process of separating two substances of differing densities by high speed spinning to create centrifugal force. Typically used to separate suspended particles from liquid.

CFM:
Cubic feet per minute. The amount of air, in cubic feet, that flows through a given space in one minute. 1 CFM equals approximately 2 liters per second (l/s).

CHEMICAL DOSAGE:
The amount of chemical added to a system, usually expressed as ppm, or pounds of chemical per million pounds of water.

CHLORINATION, DECHLORINATION:
The act of removing chlorine from water, usually via a reducing agent or strong aeration.

CHLORINE:
A poisonous yellow gas with chemical symbol C12 used for water treatment. It is soluble in water but can be removed by reducing aeration and reaction with sunlight.

CHLORINE DEMAND:
The relation of the amount of chlorine to be added to a system to react with chlorine-oxidizable material until a free residual in a given system is achieved.

CHROMATOGRAPHY:
The separation of substances in a mixture based on their affinity for certain solvents and solid surfaces.

CHLORINATION:
Adding chlorine or a chlorine derivative to water to prevent the growth of various organisms that cause biofouling.

CIRCULATING WATER RATE:
Quantity of water pumped from the basin to the equipment to be cooled, usually expressed as gallons per minute (gpm).

CLARIFICATION:
To clear 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 1µm or larger are found in a cubic foot of air.

COLD STERILIZATION:
Removal of all bacteria by filtration through a sterilizing grade 0.2µm absolute filter.

COLD WATER TEMPERATURE (CWT):
Temperature of the water entering the cold water basin before addition of make-up.

COLUMN:
Tube or cylinder containing the chromatographic bed or stationary phase, usually in the form of beads.

COMPATIBILITY:
Term used in relation to the non-reactivity of filter materials with the substance to be filtered.

COMMISSIONING:
Start-up of a building that includes testing and adjusting HVAC, electrical, plumbing, and other systems to assure proper functioning and adherence to design criteria. Commissioning also includes the instruction of building representatives in the use of the building systems.

CONCENTRATION:
The process of increasing solids per unit volume of solution, usually by evaporation of the liquid; also, the amount of material dissolved in a unit volume of solution. This occurs due to evaporation that cools the water. It is normally expressed directly as ppm or indirectly as mhos conductivity.

CONCENTRATOR:
An apparatus or method for removing some of the water from a sample to concentrate the substances dissolved or suspended in it; usually used to concentrate solutions of biological macromolecules, e.g., proteins and nucleic acids.

CONDUCTIVITY:
The ability of water to conduct electricity. When measured with a standard apparatus, it is called specific conductivity and is a function of the total ionic dissolved solids. As a rule of thumb, TDS = 2/3 specific conductance measured as micromhos.

CONSTANT AIR VOLUME SYSTEMS:
Air handling system that provides a constant air flow while varying the temperature to meet heating and cooling needs.

COOLING EFFICIENCY:
The percent of the temperature drop across the media compared to the Wet Bulb Depression. I.E. if the Wet Bulb Depression is 30 degrees (f) (as in the above example) and the actual temperature drop measured across the cooling media is 27 degrees (f), the cooling efficiency of the media is 90%. (27/30 = .90). The cooling efficiency is also referred to as “Saturation Efficiency” because it refers to the amount of moisture that is packed in the air. 100% Saturation Efficiency would indicate a temperature drop of 30 degrees (f) in the above example of wet bulb depression.

COOLING WATER:
Water circulated through a cooling system to remove heat from certain areas.

CORROSION:
To be dissolved away, usually by oxidation or acidification. This usually refers to metal loss in cooling systems, often recognized by the local reaction of the dissolved metal with oxygen, carbon dioxide, acids or galvanic action. May result in general (widespread) or pitting loss of the metal.

CORROSION INHIBITOR:
Chemical used in a system to prevent corrosion.

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 (referred to as concentrate).

CURTAIN DROP:
A failsafe device to mechanically release the sidewall curtain winch on power failure or in high temperature situations, causing curtains to fall open.

CYCLES OF CONCENTRATION:
Compares dissolved solids in makeup water with solids concentrated through evaporation in the circulating water. Since chlorides are soluble in water, for example, the cycles of concentration are equal to the ratio of chlorides in circulating water to chlorides in makeup water.

DEAD END (CONVENTIONAL) FILTRATION:
Feed stream flows in one direction only, perpendicular to and through the filter medium to emerge as product or filtrate.

DEFFERENTIAL PRESSURE:
The difference in pressure between the upstream and downstream sides of the filter. Also called P, psid or pressure drop. May be modified with applied, available, clean, dirty, initial, or maximum.

DEFLOCCULATION:
The ability of some materials such as polyphosphides to peptize and disperse suspensions of colloidal particles.

DELIGNIFICATION:
The dissolving of the lignin portion of cooling water wood usually by strong alkaline and/or oxidizing agents.

DELTA () P:
See "Differential Pressure".

DEPTH FILTER:
A matrix of randomly distributed fibers creating a tortuous path with pores of undefined size and shape.

DEWPOINT:
The temperature at which moisture begins to form on a slick surface indicating 100% saturation of the air with moisture. That is how the dew gets on the grass in the morning. The dry bulb air temperature drops to the web bulb temperature level.

DIATOMACEOUS EARTH FILTRATION:
A filtration method that employs 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 both cation and anion exchange resin beds, or a mixed resin bed to remove both positive and negative ions. The purity of water is measured by its electric resistance. High quality DI water has a minimum resistance of 18 megohm per cm at 25ºC.

DIFFUSIONAL INTERCEPTION:
In gas filtration, at low gas flow velocities, very small particles <0.1µm are subject to Brownian motion. Thus they can move out of the gas streamlines and become intercepted by the filter.

DIFFUSIONAL FLOW TEST:
A test to determine the integrity of a filter. The test is based on the measurement of diffusive (diffusional) flow of a gas through a wetted filter. Either the gas or the downstream liquid, displaced by the gas, may be measured. In addition, the transition from diffusional flow to bulk flow (i.e. bubble point) can be determined.

DIRECT INTERCEPTION:
In gas filtration, particles larger than the pores are removed by direct interception with the filter surface. Some particles smaller than pores can be removed as well depending on the probability, which is proportional to their size, of hitting the surface.

DIRECT MOUNT PAD SYSTEM:
A low-cost alternative to a doghouse plenum pad cooling installation, mounting pads with as little as a 6-inch gap over tunnel inlets. Direct mount systems are less efficient than doghouse plenum systems but can perform adequately when properly designed and installed. They are sometimes the only feasible way to add evaporative pad cooling to an existing house.

DIRT-HOLDING CAPACITY:
Amount of dirt or debris retained by a filter in grams per unit area of the filter medium.

DISINFECTING:
To remove microorganisms from a particular surface or liquid.

DISPERSANT:
A chemical that causes particulates in a water system to remain in or be placed into suspension.

DISSOLVED SOLIDS:
Total solids that have been dissolved into a liquid. They may be ionic and/or polar in nature.

DISTRIBUTION HEADER:
Pipe or flume delivering water from inlet connection to lateral headers, troughs, flumes, or distribution basins.

DISTRIBUTION SYSTEM:
Those parts of a tower, beginnings with the inlet connection, which distribute the hot circulating, water within the tower to the points where it contacts the air. In a counterflow tower, this includes the header, laterals, and distribution nozzles. In a crossflow tower, the system includes the header or manifold, valves, distribution box, basin pan, and nozzles.

DMF:
Drug Master File. A written document that explains the formulation of an active ingredient, and is referenced in an Investigational New Drug (IND), New Drug Application (NDA), or Amendment to New Drug Application (ANDA) from a company.

DOGHOUSE PLENUM:
A small structure, 18-24 inches wide inside, built onto the side of a poultry house opposite the tunnel air inlets and accommodating evaporative cooling pads. Also referred to as a “pad room”. These allow for air to pass through cooling pads at low velocity (for high cooling efficiency) before passing through the smaller area of the tunnel inlets. They also allow personnel entry for pad maintenance.

DOP:
Dioctyl phthalate, a plasticizer that can be aerosolized to particles of extremely uniform size of the order of 0.3µm. Retention of DOP aerosol is used a s standard procedure for pore size rating of air filters.

DOWNSPOUT:
A short vertically placed pipe or nozzle used in a gravity distribution system to divert water from a flume or lateral to a splasher.

DOWNSTREAM SIDE (OF FILTER):
The filtrate or product stream side of the filter.

DRIFT:
Water lost as liquid droplets entrained in the exhaust air. It is independent of water lost by evaporation. Units may be in lbs./hr. or percentage of circulating water flow. Drift eliminators control this loss.

DRIFT ELIMINATORS:
An assembly constructed of wood, plastic, cement board, or other material that serves to remove entrained moisture from the discharged air.

DRY BULB:
The ambient (surrounding air) temperature taken with a thermometer.

DRY HEAT STERILIZATION:
Sterilization at or above 180ºC using a convection or forced air oven without moisture; may concurrently depyrogenate if adequate time and elevated temperature are employed.

E. COLI:
Escherichia coli; The most prevalent bacteria in the gastrointestical tract of humans and animals. It occurs in solids and water as a result of fecal contamination.

EFFECTIVE FILTRATION AREA:
The portion of filter that fluid flows through during the filtration (EFA) process.

EFFLUENT:
The fluid which has passed through a filter (syn: filtrate or product stream); also, outflow from other types of treatments such as wastewater treatment plants.

EPA:
Environment Protection Agency regulates environmental monitoring. Establishes and enforces its guidelines.

ELECTRONIC CONTROL:
Integrated electronic controllers include sensors for temperature, static pressure and sometimes relative humidity; they are programmable to make ventilation setup adjustments without the need for resetting of individual thermostats, etc., and give more precise control of in-house conditions.

ENTERING AIR:
Surrounding air from the atmosphere which enters through the louvers on an Induced draft or is discharged by a fan on a Forced Draft.

ENTERING WET-BULB TEMPERATURE:
Average wet-bulb temperature of the entering air. Includes any effects of recirculation.

ETO (STERILIZATION):
Chemical sterilization using ethylene oxide usually 12:88 (12% ETO in Freon). Employs a slightly elevated temperature, 66ºC (150ºF), and high relative humidity to facilitate permeation of the ethylene oxide into the material being sterilized.

EVAPORATION LOSS:
Water evaporated from the circulating water into the atmosphere by the cooling process.

EVAPORATION RATE:
The rate at which water is absorbed into the air passing through the cooling media. For practical purposes, this rate is measured in gallons of water per hour (or minute).

EVAPORATIVE COOLING:
When water evaporates into the air, it has the effect of cooling the air. Evaporative cooling for poultry housing has been found feasible in all but the most humid climates. Water may be sprayed or fogged into the air, or blown over a medium saturated with water.

EVAPORATIVE COOLING PAD:
A material on which water is applied which will allow air to pass through it, thus facilitating evaporation and reducing the air temperature. These can be paper or fiber and range from 2” to 6”. The angle and size of pad “flutes” or openings affect the cooling efficiency and static pressure drop across a pad. Pad choices must take these factors into consideration, along with pad area and air velocity needed through pad for desired cooling efficiency.

EXHAUST AIR:
The mixture of air and its associated vapor leaving the system (see Air Flow).

EXHAUST VENTILATION:
Mechanical removal of air from a portion of a building (e.g., piece of equipment, room, or general area).

EXTRACTABLES:
Chemicals which may be leached from a filter during a filtration process; usually tested for by soaking in water under controlled conditions; may be removed by pre-flushing with suitable liquid.

FAB:
Fabrication fabrication area (e.g., in electronics industry).

FAN:
A device for moving air. The fan design may be either an axial flow propeller or centrifugal blower. The fan can be applied as induced draft or forced draft.

FAN DRIVEN ASSEMBLY:
Mechanical components furnishing power to the fan, usually consisting of driver, drive shaft, speed reducer, and supporting members.

FAN DRIVEN OUTPUT:
Horsepower input to the driver. For 3-phase alternating current (ac) motors:
hp = (amps x volts x 3 x Power Factor x Efficiency) / 746

FAN DRIVER OUTPUT:
Brake horsepower output of the driver to the drive shaft. Fan driver input x motor efficiency.

FAN GUARD:
A protective screen installed either at the inlet of a forced draft fan or at the exit of an induced draft fan.

FAN PITCH:
The angle that a fan blade makes with the plane of rotation.

FDA:
Food and Drug Administration.

FERMENTATION:
Generally referred to as enzymatically controlled breakdown of an energy rich compound (as a sugar to produce ethyl alcohol, carbon dioxide, and energy) by the action of yeasts which carry the necessary enzymes (bacterial fermentations also occur).

FILTER (noun):
A device for carrying out filtration which consists of the filter medium and suitable holder for constraining and supporting the filter in the fluid path.

FILTER (verb):
To pass a fluid containing particles through a filter medium whereby particles are removed from the fluid.

FILTER EFFICIENCY:
A measurement of how well a filter retains particles. Usually expressed as the percentage of retention of particles of a specific size by a filter; see also "Beta Ratio" and "Log Reduction Value."

FILTER MEDIA MIGRATION:
Problem caused by a filter medium which is constructed of a non-continuous or fibrous polymeric matrix such that portions of the filter change structure causing undefined pore size/distribution, as a function of fluid flow.

FILTER MEDIUM:
The permeable material that removes particles from a fluid being filtered.

FILTRATE:
The effluent of a filtration process. The filtered product.

FILTRATION:
The process by which particles are removed from a fluid by passing the fluid through a permeable material.

FLASH PASTEURIZATION:
The process of briefly heating a beverage to destroy objectionable enzymes and microorganisms. See "Pasteurization".

FLOAT VALVE:
A valve that is actuated by a float, generally used to control make-up water supply.

FLOCCULATION:
The process of agglomerating coagulated particles into settleable flocs, usually of a gelatinous nature.

FLOW DECAY:
Decrease in flow rate as a result of filter plugging or clogging.

FLOW DECAY TEST:
An experiment to determine flow rate and throughput of a filter type or combination of filters on a specific liquid, usually by using a small area filters, to determine the sizing of a filter system by extrapolation.

FLOW CONTROL VALVE:
A manually controlled valve generally located in the hot water supply line used to increase or decrease the flow of a liquid in a system.

FLOW RATE:
It is the speed at which a liquid flows and is measured in gallons or liters per minute. Flow rate of a liquid can be affected by the liquids' viscosity, differential pressure, temperature and type of filter used.

FOGGING:
A fog condition created when the exhaust air or plume from a cooling tower becomes supersaturated so that part of the water vapor condenses into visible liquid droplets.

FOGGING NOZZLES:
Fine droplet spray nozzles or misters used to introduce water vapor into an air stream for evaporative cooling. Most efficient nozzles deliver 1 gal/hr at 160-200 psi.

FORCED AIR FURNACE:
A direct fired heating furnace with built-in air blower used to maintain temperatures in the poultry house. These can be used alone or in conjunction with brooding equipment.

FORWARD FLOW TEST:
An integrity test measuring air diffusion. See "Diffusional Flow Test."

FRACTIONATION:
In densitometry, the division of peaks into fractions in order to quantitate the electrophoretically separated bands. In chemistry, separation of a mixture of components into different portions (fractions).

FUNGI:
Simple, plant-like life forms that lack true roots, stems, leaves, and chlorophyll. They are filamentous in structure (e.g., mushrooms, mildews, molds, and yeasts).

GC:
Gas Chromatography; similar to HPLC except that mobile phase is an inert gas such as helium.

GASKET:
Material inserted between contact surfaces of a joint to ensure a fluid-tight seal.

GAUGE PRESSURE:
The pressure measured by a pressure gauge. Pressure above ambient pressure. Symbolized as psig when the pressure is expressed in psi units.

GLC:
Gas Liquid Chromatography.

GMPs:
Good Manufacturing Practices. Regulations promulgated by the Food and Drug Administration governing the manufacture of drugs (Ref. Code of Federal Regulations 21 CFR 210 & 211), medical devices (21 CFR 820), and Large Volume Parenterals (21 CFR 212 proposed).

GPH:
Gallons per hour.

GPM:
Gallons per minute.

GRAINS OF MOISTURE PER POIUND OF DRY AIR:
A method of measuring actual water vapor (moisture) in a pound of dry air, most often referred to as “humidity ratio”. I.E. 50 grains of moisture at 100 degrees (f) equals 12% relative humidity and 70 degrees (f) wet bulb at sea level.

GROUNDWATER:
Water pumped from underground rivers, wells, and lakes.

GROUNDWATER TESTING:
Process of collecting and analyzing groundwater in areas where contamination is suspected such as dumpsites and landfills. Look for pesticides, dissolved metals, etc.

GPM:
(abbr.) Gallons per minute.

HALF LIFE:
In water treatment, the time it takes to lose of a slug fed product from the system through blowdown, drift and windage when taking into account its continuous concentration by evaporation and dilution by fresh makeup.

HARNESS, CALCIUM:
The calcium compounds dissolved in water, usually expressed as calcium carbonate.

HARDNESS CARBONATE:
The calcium and magnesium carbonate and bicarbonate dissolved in water, expressed as calcium carbonate. Other metallic cations such as ferrous iron, barium, zinc and manganous ions are also included.

HARDNESS, MAGNESIUM:
Magnesium compounds dissolved in water, expressed as calcium carbonate.

HARDNESS, NONCARBONATE:
The difference between the total hardness and the total alkalinity of a water.

HEAT PUMP:
A unit that handles both heating and cooling. In some climates, a heat pump may handle your heating and cooling needs more efficiently than a furnace and air conditioner.

HIMA:
Health Industry Manufacturer's Association. A trade association, whose membership includes both pharmaceutical manufacturers and filter manufacturers, that defines and sets standards governing the validation of filters for sterilizing liquids.

HOLD-UP VOLUME:
Also called Retention Volume. Volume of fluid retained in a filter and/or housing after purging the assemble with air or suitable gas.

HPLC:
High Pressure Liquid Chromatography allows separation and analysis of very small quantities of complex mixtures with high resolution and great sensitivity. Purpose: identify nature of a compound or measure amount or concentration of a compound.

HYDROPHILIC:
Having an affinity for water; a membrane which will wet with aqueous solutions.

HYDROPHOBIC:
Literally, fearing water; a membrane which cannot be wetted by and repels aqueous and other high surface tension fluids; when pre-wetted with low surface tension fluid, such as alcohol, the filter will then wet with water.

IMPACTION:
Retention mechanism in gas filtration. Also called Inertial Collection and Inertial Impact. As the gas stream lines bed in the vicinity of the filter, the carried particles continue in a straight line due to their inertia and impact the filter. Effective primarily for particles about 0.3µm and larger, at high gas velocities and low filter porosity.

IMPURITIES:
Any substance that contaminates another.

IN SITU:
Latin for "in place." Sterilization or integrity testing of a filter in the system rather than as an ancillary operation such as in autoclave or bubble point stand.

INERT:
Chemical inactivity; unable to move; totally unreactive.

INERTIAL COLLECTION:
See "Impaction."

INERTIAL IMPACT:
See "Impaction."

INLET AIR:
(see Entering Air).

INLET PRESSURE:
The pressure entering the inlet side of the filter. Also called upstream pressure or line pressure.

INTEGRITY TEST:
A non-destructive test which is used to predict the functional performance of a filter. The valid use of this test requires that it be correlated to standardized bacterial or particle retention test. Examples: Bubble Point Test, Diffusion Test, Forward Flow Test, Pressure Hold Test.

INTERCEPTION:
See "Direct Interception."

ION EXCHANGE COLUMNS:
Vessels filled with ion exchange resin (anion, cation, or mixed) for producing conditioned or DI Water. Also, type of column used for Ion Exchange Chromatography (IEC).

ISOTROPIC (SYMMETRIC) MEMBRANE:
Membrane in which the pore openings are the same diameter throughout the thickness and on both sides of the membrane. Such membranes are non-directional, i.e., their flow characteristics are independent of which side faces the feed stream.

K or k:
The symbol for kilo or 1,000. As in kilogram (kg = 1,000g) or kilometer (km = 1,000m). In information systems, and computers, 1K means 1024 bits of information. A 64K memory stores 65,536 bits.

KINEMATIC VISCOSITY:
The ratio of absolute viscosity (poise) to the specific gravity of a fluid. The unit of kinematic viscosity is the stoke. See "Centipoise" and "Centistoke".

LINE PRESSURE:
The pressure in the supply line. Also called inlet pressure, upstream pressure.

LIVE STEAM STERILIZATION:
Sterilization by flowing saturated steam through a vented vessel or system, usually at 125ºC and 20 psi (but can be performed up to 140ºC and 35 psi.)

LOG REDUCTION VALUE (LRV):
The logarithm to the base 10 of the ratio or organisms in the feed to organisms in the filtrate. Example: Log10(109/2) = 9.7
Also used as a ratio of in/out bioburden in other sterilization methods such as autoclaving.

LOUVERS:
Members installed horizontally in a system wall to provide openings through which the air enters the system while also containing the falling water within the system. Usually installed at an angle to the direction of air flow to the system.

LVP:
Large Volume Parenteral. Intravenous injection packaged in containers of 100 – 1000 mL used to correct electrolytic imbalances, replace body fluid and provide general nutrition.

MAKEUP:
Water added to the circulating water system to replace water lost from the system by evaporation, drift, blowdown, and leakage.

MEAN FLOW PORE MEASUREMENT:
The theoretical diameter of the mean pore. It is calculated as the diameter of the pore of a wetted membrane partially voided of liquid such that air flow of the partially wetted membrane is equal to ½ the dry air flow.

MECHANICAL CONTROLS:
Controls such as thermostats and timers. These are simple and inexpensive methods of control however, their accuracy is limited and they must be set individually.

MECHANICAL EQUIPMENT SUPPORT:
Members which comprise the primary support for the fan, drive assembly. Normally steel or concrete.

MEDIA:
In filtration, the material through which fluid passes in the process of filtration and which retains particles. Also, the nutrients containing solutions in which cells or microorganisms are grown.

MEDIA MIGRATION:
Migration of the materials making up the filter medium. May cause contamination of the filtrate.

MEMBRANE FILTER:
A continuous matrix with pores of defined size.

MICROFILTRATION:
Separation of particles ranging from 0.1µm to 10µm from a fluid by passing the fluid through a membrane. Used for clarification, sterilization or to detect or analyze bacteria and other organisms and particulate matter.

MICROMETER (m):
Also referred to as "micron." It is a 1/1,000,000 of a meter (1µm = 10-6µm = .000039 in);
25.4µm = 0.001 inch;
60µm = approximately the diameter of a human hair.

MICROORGANISM:
An organism that is too small to be studied without the aid of a microscope.

MIL:
A unit of measure equal to one thousandth of an inch. 1 mil = 0.001 in = 0.025 mm.

MINIMUM BUBBLE POINT PRESSURE:
Also referred to as minimum critical bubble point pressure, it is a filter specification derived from diffusional flow – bubble point curves for a number of filters. It is a diffusional flow pressure just before the onset of bulk flow.

MINIMUM VENTILATION:
A wintertime ventilation mode designed to exhaust ammonia and moisture and bring fresh air into the house. Minimum ventilation is normally cycled by on-off timers, running as little as one minute in ten. Care must be taken not to under-ventilate in cold weather in an effort to save fuel.

MIXED CELLULOSE ESTERS:
Synthetic materials derived from naturally occurring cellulose. First materials used in the manufacture of membrane filters. Mixed cellulose esters membranes are used in a wide variety of applications, e.g., concentration of bacteria in water analysis (GN-6) and sampling of air.

MOTOR RATED HORSEPOWER:
Horsepower rating inscribed on name-late of the motor driving the fan. (See Rated Horsepower.) Unit: hp.

NEGATIVE PRESSURE VENTILATION:
Power ventilation in which in-house air is at a lower static pressure than the outside air, with air being pushed out of the building by exhaust fans. The partial vacuum created brings air into the building through all openings, planned or unplanned. A static pressure difference across the walls of at least 0.05 inches of water is required to ensure adequate air distribution throughout the building and avoid short-circuiting of airflow near the fans.

NFR:
Non-fiber releasing. A filter which will not release fibers into the filtrate.

NIOSH:
National Institute of Occupational Safety and Health develops basic methodology for analytical test procedures.

NOZZLE:
A device for controlled distribution of water in a cooling tower. Nozzles are designed to deliver water in a spray pattern by pressure or by gravity flow.

NYLON:
A thermoplastic, polymeric material that has high mechanical strength & compatibility with many different kinds of chemicals. When used as a membrane it is hydrophilic.

OEM:
Original Equipment Manufacturers.

ORGANIC:
Related to or derived from a living organism. Always contains carbon.

OUTDOOR AIR SUPPLY:
Air brought into a building from the outdoors (often through the ventilation system) that has not been previously circulated through the system. Also known as “Make-Up Air”.

OUTLET PRESSURE:
The pressure exiting the outlet side of the filter. Also called downstream pressure.

PARALLEL FILTRATION:
Branching a filtration setup so that two assemblies of the same pore size are in parallel, to increase flow rate or simplify filter changes.

PARTICLE:
Any discrete unit of material structure; a discernible mass having an observable length, width, thickness, size and shape.

PARTICULATE:
Relating to or occurring in the form of fine particles.

PASTEURIZATION:
Partial sterilization of a substance and especially a liquid (as milk) at a temperature and time of exposure that destroys objectionable organisms without a major chemical alteration of the substance. Maintaining the high temperature for only a short period of time is referred to as 'flash' pasteurization.

PERISTALTIC PUMP:
A pump functioning by alternate pinching and release of tubing which drives the fluid forward in a pulsing action. The major advantage's are that the peristaltic pump is noninvasive, i.e., the pump does not contact the fluid being filtered, only the inner wall of the tubing contacts the fluid and the low shear imparted.

PERMEABILITY:
The degree to which a fluid will pass through a permeable substance under specified conditions. The space or void volume between molecules allowing fluid flow.

PERMEATE:
The fluid which passes through a membrane.

pH:
The inverse (negative) logarithm to the base 10 of hydrogen ion concentration. Measure of a substance's acidity or alkalinity with 7 being neutral. Measure of hydrogen ion concentration.

PLENUM:
Air compartment connected to a duct or ducts.

POISE (ABSOLUTE VISCOSITY):
Numerically equal to the force required to move a plane surface of one square centimeter over another plane surface at the rate of one centimeter per second when the surfaces are separated by a layer of fluid one centimeter in thickness (dyne sec/cm2).

POLYPROPYLENE:
A thermoplastic polymeric material which is resistant to a broad range of chemicals. When used as a membrane, polypropylene is hydrophobic.

POLYSULFONE:
Commonly used membrane material. Has excellent flow rates, high mechanical strength, resistant to a broad range of temperatures (can be sterilized) and is hydrophilic. Is not resistant to exposure to many organic solvents.

PORE SIZE:
Diameter of pore in membrane.

PORE SIZE-ABSOLUTE RATING:
The rated pore size of a filter at which particles equal or larger than the rated pore size are retained with 100% efficiency.

POROSITY:
The percentage of the filter volume which is void space (syn. Void volume). Also, number of pores per square centimeter of filter area.

POSITIVE PRESSURE VENTILATION:
Power ventilation, in which the interior air is at a higher static pressure than the outside air, with air being pushed into the building by intake fans in the walls, and exiting the house through all the openings in the walls or ceiling.

POUNDS OF MOISGURE PER POUND OF DRY AIR:
Same as grains except weight of water vapor (moisture) is expressed in pounds. In same example above, the pounds of moisture would equal .009 # per pound of dry air.

POWER VENT CONTROLS:
An automatic control which adjusts air inlet opening size to maintain static pressure within ranges that allow proper airflow, thus resulting in desired air exchange rate and airflow pattern.

PPM:
Parts per million.

PRESSURE STATIC:
In flowing air, the total pressure minus velocity pressure. The portion of the pressure that pushes equally in all directions.

PRESSURE, TOTAL:
In flowing air, the sum of the static pressure and the velocity pressure.

PRESSURE, VELOCITY:
In flowing air, the pressure due to the velocity and density of the air.

PREVENTIVE MAINTENANCE:
Regular and systematic inspection, cleaning, and replacement of worn parts, materials, and systems. Preventive maintenance helps to prevent parts, material, and systems failure by ensuring that parts, materials and systems are in good working order.

PROTEIN BINDING:
Adsorption of a protein to a surface such as a cellulose nitrate or nylon membrane due to several types of interactions between the protein molecules and the surface.

PSEUDOMONAS DIMINUTA:
A type of bacteria used in sterility testing. One of the smallest bacteria (0.3µm in diameter), used to challenge a sterilizing grade filter during validation testing. Under HIMA challenge conditions (107 c.f.u./cm2 EFA), sterilizing grade filters must retain all 100% of P. diminuta.

PSYCHROMETER:
An instrument used primarily to measure the wet-bulb temperatures. Either a sling or a mechanically aspirated type of psychrometer is acceptable provided the instrument is properly shielded from radiation and the air across the wick is limited to approximately 1,000 ft/min.

PTFE:
Polytetrafluoroethylene; More commonly known as Teflon. Highly durable and resistant to a broad range of temperatures and chemicals. PTFE is hydrophobic.

RADIANT HEAT TRANSFER:
Radiant heat transfer occurs when there is a large difference between the temperatures of two surfaces that are exposed to each other, but are not touching.

RECOVERY:
Ability of a filter to recover bacteria (or other defined particles) from a solution. In Membrane Filtration Technique, expressed as percent of bacteria originally present or observed on a comparable pour plate.

RE-ENTRAINMENT:
Situation that occurs when the air being exhausted from a building is immediately brought back into the system through the air intake and other openings in the building envelope.

RELATIVE HUMIDITY:
The percent of moisture in the air compared to the amount of moisture the air could contain. This is the most common reading to be reported in the weather reports. The report of “100 degrees and 12% relative humidity (RH)” is the same as all the above examples. Using the analogy of a glass half filled with water means the glass is 50% full. It could hold an additional 50% at which point it would start to overflow if more water was added.

RETENTION:
Ability of a filter to retain particles (total number or those of a specific size) suspended in a gas or liquid. Expressed as a percent of particles originally present.

RETENTION VOLUME:
See "Hold-up Volume."

REVERSE OSMOSIS (RO):
A filtration separation method (usually crossflow or stirred cell type) operating at 200-1500 psi to overcome osmotic pressure. Pore sizes are typically in the order of 10-10 meters (107mm). Efficiency is usually described in terms of percent salt rejection with 90% being common.

SANITIZATION, SANITIZE:
To make clean by removing dirt and other extraneous materials with soap and general disinfectant so as to reduce possibility of growth and spread of pathogenic organisms.

SCALE:
The deposition on heat transfer surfaces of material normally in solution, as opposed to fouling, which is deposition of material normally in suspension.

SCFM:
Standard cubic feet per minute, i.e. units of gas flow rate. A standard cubic foot is measured as volume of gas at 760 millimeters of mercury pressure (1 bar) and 0ºC temperature.

SERIAL FILTRATION:
Filtration through two or more filters of decreasing pore size one after the other to increase throughput, filtration efficiency, or to protect the final filter.

SIDEWALL CURTAIN CONTROLS:
A mechanical device designed to open or close sidewall curtains based on desired house temperature.

SIDEWALL AIR INLETS:
Also called vent boxes, these inlets are spaced high along sidewalls for negative pressure non-tunnel mode ventilation. A modern house will have approximately 15 sq ft of inlet area per 10,000 cfm of fan capacity to be used. For transitional ventilation, enough inlet area should be provided to use half of the installed inlet area should be provided to use half of the installed tunnel fan capacity. For best performance, these inlets are automatically controlled by a static pressure sensor (see Power vent controls above).

SIEVE:
A filter with straight-though capillary pores with identical dimension, e.g. a screen filter.

SLIME:
A deposit build-up directly related to the excessive growth of microorganisms that secrete or form thick, sticky material. These slimes cause tube pluggage, reduce heat transfer, entrap migratory suspended solids and can result in underdeposit corrosion.

SOLUBILITY:
The ability of one material (the solute) to dissolve in another (the solvent).

SOLUTIONS:
Liquid mixtures that are uniform throughout.

SOP:
Standard Operating Procedure. A written document that explains how to complete a specific production-oriented task.

SPARGING:
The process by which steam, compressed air, or gas is forced into a liquid through perforations or nozzles in a pipe as part of fermentation.

STANDARD (NORMAL) PRESSURE:
A pressure of 1 atmosphere (14.70 psi or 760 mm of mercury) to which measurements of quantities dependent on pressure are often referred.

STATIC PRESSURE:
A measure of potential energy per unit of volume of air. Static pressure describes the partial vacuum created in a house by exhaust fans, and goes up as the total air inlet area is decreased. It also describes the “resistance” against which the fan must work. Static pressure is usually measured in inches of water. Poultry house ventilation systems are normally designed to operate at static pressures in the 0.04 – 0.10 inch range.

STERILE, STERILITY, STERILIZATION:
To make or be free of any viable microorganisms. Demonstrated by testing to show the absence of microorganisms.

STERILIZING FILTER:
A non-fiber releasing filter which produces an effluent in which no microorganisms are demonstrable when tested by the method specified in the current edition of the United Sates Pharmocopeia. Usually accepted as 0.2µm pore-size absolute rating.

SUMP:
Lowest portion of the basin to which cold circulating water flows: usually the point of circulating pumps suction connection. Also known as Basin Sump.

SURFACE TENSION:
Also "interfacial tension." Tendency of the surface of a liquid to contract to the smallest area possible under the existing circumstances. Defined as a force in dynes acting on a line 1 cm long lying in the surface of the liquid.

SUPPLY HEADER:
Portion of the water supply system, which contains the valves and distribution boxes in a crossflow tower or the lateral pipes in a counterflow tower.

SURFACTANT:
A soluble compound that reduces the surface tension of a liquid, or reduces interfacial tension between two liquids (causing formation or micelles) or between a liquid and a solid, thereby functioning as a wetting agent.

SVP:
Small Volume Parenteral; Typically administered to a patient as a bolus or single syringe injection.

TARE:
A deduction of weight, made in allowance for the weight of a container or medium; the initial weight of a filter.

TENSILE STRENGTH:
Resistance to breaking as a function of tensile force (tension). The amount of force required to break a membrane by stretching. Usually accompanied by measurement of Elongation-at-Break, the total amount of stretching realized at break, expressed as percent of the original length.

THERMOPHILIC:
A Type of bacteria that thrives in very high temperatures.

THROUGHPUT:
The amount of solution which will pass through a filter prior to clogging.

TOTAL DISSOLVED SOLIDS:
Is the portion of the total solids in the sample that passes through the filter and is indicated by the increase in weight in the vessel after the filtrate has been dried at 180ºC.

TOTAL SOLIDS:
The material residue left in the vessel after evaporation of a sample and its subsequent drying in an oven at 103-105ºC. The increase in weight over that of the empty vessel represents the total solids. Used in analyzing drinking water.

TOTAL SUSPENDED SOLIDS:
Is the portion retained on the filter and indicated by an increase in the weight of the filter after drying at 103-105ºC. Used in analyzing drinking water.

TORTUOUSITY:
An imaginary continuous course or path that can be traced from a point on the upstream side of a filter to a point on the downstream side. Pathway traveled by the liquid or gas during filtration.

TUNNEL VENTILATION:
A form of negative pressure ventilation in which exhaust fans and large air inlets are at opposite ends of the house, so that ventilation air travels the length of the building at high air velocity (at least 400 feet per minute). The wind-chill effect promotes cooling of birds during hot weather.

TUNNEL VENTILATION INLETS:Large openings on the sidewall or end of a house, with total area usually equal to the house cross-sectional area, but greater to accommodate evaporative cooling pads when these are installed. Tunnel inlets are normally fully open during tunnel ventilation, and fully closed by a moveable curtain at all other times.

ULTRAFILTRATION (UF):
A separation method operating at 50-200 psi in crossflow filtration mode. Efficiency is approximately 90%. Used to separate large molecules according to their molecular weight.

UPSTREAM SIDE (of filter):
The feed side of the filter.

Unit ventilator – A fan-coil unit package device for applications in which the use of outdoor-and return-air mixing is intended to satisfy tempering requirements and ventilation needs.

U.S.D.A.:
United States Department of Agriculture.

U.S.P.:
United States Pharmacopeia/National Formulary.

VACUUM:
The depression of pressure below atmospheric pressure.

VALIDATION:
Demonstration that a process or product does what it is supposed to do by challenging the system and providing complete documentation.

VARIABLE AIR VOLUME SYSTEM(VAV):
Air handling system that conditions the air to constant temperature and various the outside airflow to ensure thermal comfort.

VENTILATION AIR:
Defined as the total air, which is a combination of the air brought inside from outdoors and the air that is being re-circulated within the building. Sometimes, however, used in reference only to the air brought into the system from the outdoors; this document defines this air as “outdoor air ventilation”.

VENTILATION RATE:
The rate at which indoor air enters and leaves a building. Expressed in one of two ways: the number of changes of outdoor air per unit of time (air changes per hour, or “ach”) or the rate at which a volume of outdoor air enters per unit of time (cubic feet per minute, or “cfm”).

VISCOSITY:
A resistance to flow as a function of force, or gradual yielding of force. Viscosity is in units of centipoises or centistokes. For a given filter and differential pressure, flow rate will decrease as viscosity increases; e.g. oil will have a flow rate much slower than water. The viscosity of water is 1 centipoise.

VOLATILE:
Evaporates easily, converts easily from liquid form to gas.

WATER BREAKTHROUGH TEST:
An integrity test for hydrophobic filters in which the resistance to water flow is overcome by a specific pressure such that water will flow through a correspondingly specific pore size of the filter. Also called a water intrusion test. Useful test to determine gross loss of integrity (e.g., installation integrity) and filter hydrophobicity.

WATER-FORMED DEPOSIT:
Any accumulation of insoluble material derived from water or formed by the reaction of water upon surfaces, including scale, sludge, foulants, sediments, corrosion products or biological deposits.

WET BULB:
The lowest temperature level of the air that can be reached by evaporatively cooling the air.

WET BULB DEPRESSION:
The difference between the Dry Bulb and Wet Bulb temperatures. I.E. if Dry Bulb is 100 degrees (f) and the Wet Bulb is 70 degrees (f), the Wet Bulb Depression if 30 degrees (f). The Wet Bulb Depression is used to determine the percent of efficiency of the cooling media.

WETTING AGENT:
A surfactant added to a membrane to assure complete intrusion (wetting) by a high surface tension fluid such as water.

ZONE:
The occupied space or group of spaces within a building which has its heating or cooling controlled by a single thermostat.



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