A.P.I.
(API):
American
Petroleum Institute.
ABSOLUTE PRESSURE:
Pressure above an
absolute vacuum. One atmosphere (14.7 p.s.i.) greater than
gauge pressure. Symbolized as psia when the pressure is
expressed in psi units.
ABSORPTION:
The taking in,
incorporation or reception of gases, liquids, light or heat.
(phys/chem.)
Penetration of one substance into the inner structure of
another. Occurs between a gas or vapor and a liquid.
The process of movement of a drug
from the site of application into the extracellular
compartment of the body.
ACTIVATED
CARBON:
Charcoal which is activated
by heating to 800-900ºC forming 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 and in automotive applications as cabin
air filters. 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.
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.
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.
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. The efficiency of a filter expressed by the number
of particles of a given size upstream of the filter, divided
by the number of particles of that size downstream of the
filter.
BIO-DIESEL:
An organic based refined liquid, similar to USA No. 2
diesel, produced from soybeans, rapeseeds, sunflower seeds
or other organic materials.
BIOBURDEN:
The load or level
of microorganisms in a substance to be filtered.
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.
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.
BUNA-N:
A Nitrile rubber
seal compound. This is a generic term covering many
formulations.
BURST PRESSURE RATING:
The maximum inside-out pressure that can be applied to a
filter element without outward structural or filter medium
failure.
BY-PASS FILTER
In automotive applications, a filter that
provides an alternate flow path to the full flow filter with
significantly finer filtration. Only a small percentage of
the total system flow is diverted to the bypass filter and
is returned directly to sump.
CAKE:
Solids or
contamination deposited on the filter media.
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.
CHROMATOGRAPHY:
The separation of
substances in a mixture based on their affinity for certain
solvents and solid surfaces.
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.
CLOUD POINT:
The temperature at which diesel fuel exhibits the formation
of wax crystals. Lower numbers are better.
COLLAPSE PRESSURE RATING:
The maximum outside-in differential pressure that can be
applied to a filter element without inward structural or
filter medium failure.
COLD
STERILIZATION:
Removal of all
bacteria by filtration through a sterilizing grade 0.2µm
absolute filter.
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.
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.
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).
DCA (Coolant filtration):
Dry Chemical Additive
DEF:
Diesel Exhaust Fluid (Urea).
DELTA () P:
See "Differential
Pressure".
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.
DEAD END
(CONVENTIONAL) FILTRATION:
Feed stream flows
in one direction only, perpendicular to and through the
filter medium to emerge as product or filtrate.
DEPTH
FILTER:
A matrix of
randomly distributed fibers creating a tortuous path with
pores of undefined size and shape. Commonly used in by-pass
type filters.
DIFFERENTIAL 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.
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.
DIRT-HOLDING CAPACITY:
Amount of dirt or
debris retained by a filter in grams per unit area of the
filter medium.
DOC:
Diesel Oxidation Catalyst.
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.
DOWNSTREAM
SIDE (OF FILTER):
The filtrate or
product stream side of the filter.
DPF:
Diesel Particulate Filter.
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.
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.
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.
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.
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 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.
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).
FULL-FLOW:
In automotive applications, a filter that filters the full
engine oil flow to the gallery under normal running
conditions.
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.
GPH:
Gallons per hour.
GPM:
Gallons per minute.
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.
HVAC:
Heating Ventilation and Air Conditioning.
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.
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."
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.
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.
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.
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.
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.
MICROSEPAROMETER RATING:
Indication of surfactancy in diesel fuel obtained by measuring the fuel turbidity after formed water
water-in-fuel emulsion is filtered through a standard coalescence material
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.
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.
NFR:
Non-fiber
releasing. A filter which will not release fibers into the
filtrate.
NITRATE (in Coolant Filters):
Corrosion inhibitor used to protect aluminum components and
soldered connections.
NITRITE (in Coolant Filters):
Protects against cavitation erosion and rust formation in
wet sleeved diesel engines.
NOx:
Oxides of Nitrogen.
OEM:
Original Equipment
Manufacturer.
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.
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.
PLEATED:
A filter element whose medium is arranged in uniform folds
and which has the geometric form of a cylinder, cone, disk,
or plate.
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.
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 tests. Under HIMA challenge conditions (107
c.f.u./cm2
EFA), sterilizing grade filters must retain all 100% of
P. diminuta.
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.
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. RO involves a
diffusive mechanism so that separation efficiency is
dependent on solute concentration, pressure, and water flux
rate. Reverse osmosis is most commonly known for its use in
drinking water purification from seawater, removing salt and
other substances from the water molecules.
SCA (in Coolant Filtration):
Supplimental Coolant Additive.
SCR:
Selective Catalyst Reduction.
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.
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.
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.
SIEVE:
A filter with
straight-though capillary pores with identical dimension,
e.g. a screen filter.
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.
SPIN-ON FILTER:
A throwaway bowl-and-element assembly that mates with a
permanently installed head.
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.
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.
SURFACE MEDIA TYPE:
Porous materials that retain contaminants primarily on the
surface.
SURFACTANT:
Surfactants are generally compounds that either lower the surface tension of a liquid, the
interfacial tension between two liquids, or that between a liquid and a solid. Surfactants may act
as detergents, wetting agents, emulsifiers, foaming agents, and dispersants.
TARE:
A deduction of
weight, made in allowance for the weight of a container or
medium; the initial weight of a filter.
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. The pathway traveled by the liquid or gas during
filtration.
TURBIDITY:
Refers to the cloudiness or haziness in a fluid caused by suspended particles which are generally
invisible to the naked eye (similar to smoke in air).
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
(of the filter):
The feed side of
the filter.
ULSD:
Ultra Low Sulfur Diesel.
UREA:
An organic, nitrogen based, water soluble compound which is
widely used in agriculture and now as a Diesel Exhaust Fluid
in emissions filtration systems.
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 has a flow rate
much slower than water. The viscosity of water is 1
centipoise.
WATER
BREAKTHROUGH TEST:
An integrity test
used with 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. Sometimes called a water intrusion test.
Useful test to determine gross loss of integrity (e.g.,
installation integrity) and hydrophobicity of a filter.
WOUND MEDIA TYPE:
Filter medium comprising two or more layers of continuous
strands of filaments in a fixed pattern.
WOVEN MEDIA TYPE:
Filter medium made from strands of fiber, thread or wire
interlaced into a cloth-like substance.
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