Filtration Glossary

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A

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• Absorption  -  The process of a fluid being taken into the pores of the media.
• Aerosol  -  A dispersion of small liquid particles in a gas.
• Air Filter  -  A device for removing particulate material from an airstream.
• Atmospheric Pressure  -  The pressure exerted upon the earth's surface by the air because of the gravitational attraction of the earth.

B

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• Backwash  -  The upward flow of water through a resin or filter bed in the water treatment process.  It is used to cleanse, expand and regenerate the resin or filter bed.
• Blinding  -  The loading up of the filter medium so as to reduce filtration efficiency.

C

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• Cake  -  The layer of solids deposited in the filter medium during the clarification of a slury.
• Cake Release  -  The ability of a filter medium to allow clean separation of the cake from the medium.
• Calendered Cloth  -  Cloth that has been passed through a pair of heavy rollers to reduce the thickness of the cloth or to flatten the intersections of the wires and provide a smooth surface.
• Capacity  -  The amount of containment that will be collected on a filter before specified restriction level is reached.
• Carbon Filter  -  An air purifier using activated carbon as the air cleaning agent for the removal of gaseous contaminants.
• Cartridge Filter  -  Consist of multiple cylindrical tubes mounted on holders in a pressure tank. The holders seal the ends of the tube so the water must pass through the walls of the cartridges.
• Cellulous Media  -  A filter material made from plant fiber.
• Check Valve  -  These valves are designed to allow the process fluid to flow in only one direction to prevent backflow.
• Cleaning Capacity  -  An air cleaner must constantly re-circulate indoor air in order to effectively reduce concentrations of airborne particulate contamination.
• Cleanroom  -  A room/facility in which the air supply, air distribution, filtration of air supply, materials of construction, and operating procedures are regulated to control airborne particle concentrations to meet approperate cleanliness levels.
• Clean Zone  -  A defined space in which the concentration of airborne particles is controlled to specified limits.
• Contaminant  -  Any foreign or unwanted substance which can have a negative effect on system operation, longevity, or reliability.

D

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• Density  -  The ratio of the amount of matter in an object compared to its volume.
• Diatomaceous Earth Filter  -  Made up of multiple leaf filter screens mounted on a shaft in a horizontal cylindrical tank. Flow is from both sides of each leaf into collector channels leading to the center of the shaft.
• Discharge  -  The liquid that leaves the filter after passing through the filter medium.
• Downstream Pressure  -  The pressure exiting the outlet side of the heat exchanger.

E

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• Effective Area  -  The total area of the filter media exposed to fluid flow.
• Efficiency  -  Is expressed in percentage and always less than 100%.
• Element  -  A porous device that performs the actual process of filtrarion.
• Emulsion  -  A suspension of small liquid droplets within a second liquid that will not mix.
• Emulsion Cleaner  -  A cleaner consisting of organic solvents dispersed in an aqueous medium with the aid of an emulsifying agent.

F

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• Filter Life  -  The duration, time or volume, that a filter can operate effectively between replacement and/or cleaning.
• Filter Medium  -  A porous sheet capable of passing liquid through while retaining solids by means of mechanical separation.
• Flow Rate  -  The amount of fluid that flows in a given time past a specific point.
• Fluid  -  A substance that deforms and changes position when put under stress.
• Fluid Pressure  -  Fluid at rest, exerts a force perpendicular to any surface in comes in contact with.

G

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• Gasket  -  A seal between two components, usually bolted.

H

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• HVAC  -  Used in both residental and commercial systems to controll air quality, humidity, and temperature in indoor spaces.

I

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• Inlet Pressure  -  See upstream pressure

J

K

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• Kinematic Viscosity  -  The ratio of dynamic viscosity to density or the resistive flow of a fluid under the influance of gravity.  

L

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• Laminar Flow  -  Generally happens when dealing with low Reynolds numbers in pipes. This could be due to low velocities, large diameters or high viscosities.
• Line Pressure  -  The pressure in the supply line.

M

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• Media Filter  -  A mechanical filter is a vertical cylindrical vessel that contains some sort filter media. In the oil patch, this will be one to several layers of sand, gravel and/or crushed anthracite.  It may also use walnut shells for the filtration media.

N

O

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• Organic Contaminant  -  Carbon-based chemicals, such as solvents and pesticides, which enter water through cropland runoff or discharge from factories.
• Osmotic Pressure  -  The pressure created by the difference in concentration of the constituents on either side of the membrane, and this pressure drives the osmosis process.
• Outlet Pressure  -  See downstream pressure

P

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• Particulate  -  Solid material suspended in water.
• Permeability  -  The quality of the soil to enable water to move downward through the soil.
• Porosity  -  A measure of the open area of a filter media.  Sometimes called volume of voids.
• Pottable Water  -  Denotes whether water is suitable for human consumption.
• Precoating  -  The operation of depositing on inert material prior to beginning filtration.
• Pressure  -  It is the force exerted perpendicular to the surface of an object and is expressed as force per unit area.
• Pressure Differential  -  The pressure difference between two points of a system.
• Pressure Loss  -  The difference in pressure between two points, usually caused by friction resistance in the pipe, but moisture can also affect it.

Q

R

S

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• Scale  -  Rust or corrosion products adhering to the inner surfaces of pipe.  It can decrease the ability to transfer heat and increase the pressure drop for flowing fluids.
• Sediment  -  Matter present in a water supply, commonly diry or sand, that enters the water due to aging pipes.
• Specific Gravity  -  The density or ratio of any substance to another substance.  It sometimes may be called just gravity or relative density.
• Strainer  -  A closed vessel that collect solid particles to be separated while passing a fluid through a removable screen.
• Supply Air  -  A mixture of re-circulated air and outside air which has been conditioned and delivered to the space.
• Surface Loading  -  The accumulation of collected dust on or close to the upstream surface of filter media.
• Surface Media  -  Filter medias that are thin, cellulosic, microfiber or membrane material and, due to construction, generally provides high flow rate, low pressure rate, and high efficiency, ...
• Suspended Solids  -  This figure is the sum of all of the suspended material found in a water sample or process stream.

T

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• Tackifier  -  A substance applied to filter media to increase the retention of dust.
• Temporary Strainer  -  A startup strainer, also known as a witch’s hat or conical strainer, in installed in a system to remove unwanted debris from the process stream.
• Thermal Sealing  -  A method of joining two or more layers of media together using heat.
• Tracer Gases  -  Compounds such as sulfur hexafluoride, which are used to identify suspected pollutant pathways and to quantify ventilation rates.
• Two-stage Air Cleaner  -  A dust removal system for intake air with a built-in pre-cleaner and an element.
• Turbidity  -  The cloudiness or haziness of a fluid caused by individual particles (suspended solids) that are generally invisible to the naked eye.
• Turbulent Flow  -  The flow rate at which laminar flow is exceeded and filtration performance is adversely affected.

U

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• Underrating  -  Operating a filter at less than manufacturers stated cfm capacity.
• Uniform Density  -  Having the same weight per unit volume of filter media from the upstream (influent) to the downstream (effluent) side of the filter.
• Unitary Filter  -  Individual filters when joined with others of the same type, form a filter bank.
• Upstream Pressure  -  The pressure entering the inlet side of the heat exchanger.

V

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• Vapor  -  The gas state of a liquid or solid.  Both vapor and gas are basically the same thing.
• Velocity  -  The rate of change or displacement with time.
• Ventilation  -  The introduction of outdoor air into a building by mechanical means.
• Ventilation Rate  -  The rate at which outdoor air enters and leaves a building.
• Viscosity  -  The measure of the internal friction/resistance to the flow of a liquid.

W

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• Water Based  -  A coating in which the film forming ingerdients are dissolved in or suspended in a volatile system containing water as the major solvent.
• Water Desalination  -  The process of removing salt from water for agriculture and to provide drinking water.
• Water Hammer  -  Occurs when a valve is suddenly opened or closed.
• Water Hardening  -  Process of hardening high carbon steels by quenching in water or brine, after heating.
• Water Softener  -  Used to remove dissolved minerals from water.  Hard water can leave mineral scale after evaporation.
• Water Treatment  -  The manipulation of incoming water to make it suitable for the intended purpose.

X

Y

Z

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• Zone  -  The occupied space.