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Filtration Terminology
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P-W
E
E. COLI:
Escherichia coli is the most prevalent bacteria in the gastrointestical tract of
humans and animals. It occurs in solids and water as a result of fecal
contamination.
ETO STERILIZATION:
Chemical sterilization using ethylene oxide at an elevated temperature of
1500ºF, 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 process.
EFFLUENT:
The fluid which has passed through a filter (filtrate or product stream);
outflow from other treatment such as wastewater treatment plants.
ELECTROSTATIC PRECIPITATOR:
A type of particulate filtration control that attracts charged particles to
oppositely charged surfaces to collect airborne particulates. The particles are
charged by ionizing the air with an electric field. The charged particles are
then collected by a strong electric field generated between oppositely-charged
electrodes.
EPA:
Environment Protection Agency regulates
environmental monitoring. Establishes and enforces guidelines.
EXTRACTABLES:
Chemicals 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.
F
FERMENTATION:
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 cary the necessary enzymes. Bacterial
fermentations also occur.
FILTER:
A specialized piece of equipment for
carrying out filtration, consisting of the filter medium and suitable holder for
constraining and supporting the filter in the fluid path.
(To) FILTER:
Passing a fluid containing particles through a filter medium wherein particles
are removed the fluid.
FILTER EFFICIENCY:
A measurement of how well a filter retains
particles. The percentage retention of particles of a specific size by a filter.
FILTER MEDIA MIGRATION:
Problem caused by a filter medium
constructed of a non-continuous or fibrous polymetric matrix. Portions of the
filter change structure causing undefined pore size/distribution, as a function
of fluid flow.
FILTER MEDIUM:
Permeable material that removes particles from fluid being filtered.
FILTRATE:
The end product of the filtration process . .the liquid exiting the filtrate
outlet.
FILTRATION:
Removal of particles from a fluid by
passing the fluid through a permeable material.
FLOW DECAY:
Decrease in flow rate caused by filter plugging or clogging.
FLOW DECAY TEST:
Determines flow rate and throughput of a
filter type or combination of filters on a specific liquid, usually by using
small area filters, to determine the sizing of a filter system.
FLOW RATE:
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. Measuring air diffusion.
G
GAUGE PRESSURE:
Pressure measured by a pressure gauge. Pressure above ambient pressure . . psig
when the pressure is used in psi units.
GMPs:
Good Manufacturing Practices. Food and
Drug Administration regulatons governing the manufacture of drugs.
H
HIMA:
Health Industry Manufacturer’s Association defines and sets standa governing the
validation of filters for sterilizing liquids. . . a trade association, whose
membership includes pharmaceutical manufacturers and filter manufacturers.
HYDROPHILIC:
Water accepting.
HYDROPHOBIC:
A membrane which repels and cannot be
wetted by 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.
HYDROMETER:
An instrument used to measure the density of a liquid.
I
IMPACTION:
Gas filtration: Retention mechanism . 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 0.3mm and larger, at high gas velocities
and low filter porosity.
IMPERMEABLE:
Material that does not permit fluids to
pass through.
INFLUENT:
Fluid entering the filter.
IN-LINE FILTER:
A filter assembly in which the inlet, outlet & filter element asiz are in a
straight line.
IN SITU.
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.
INLET PRESSURE:
Pressure entering the inlet side of the filter. Also called upstream pressure or
line pressure.
INTEGRITY TEST:
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.
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.
ISOTROPIC (SYMMETRIC) MEMBRANE:
Membrane in which the pore openings are the same diameter throughout the
thickness and on both sides of the membrane. Non-directional, their flow
characteristics are independent of which side faces the feed stream.
K
K or k:
the symbol for kilo (1,000).
KILOGRAM:
(kg = 1,000g). Kilometer (km = 1,000m). In computers, 1K = 1024 bits of
information. 64K memory = 65,536 bits.
L
LINE PRESSURE:
Inlet pressure, upstream pressure. The
pressure in the supply line.
LIVE STEAM STERILIZATION:
Sterilization by flowing saturated steam through a vented vessel or system,
usually at 257ºF and 20 psi (Can be performed up to 284ºF and 35 psi.)
M
MANOMETER:
A U-shaped tube filled with a specific liquid. The differrence in height between
the liquid in each leg of the tube gives directly the difference in pressure on
each leg of the tube. Used to monitor differential pressure.
MEAN FLOW PORE MEASUREMENT:
It is calculated as the
diameter of the pore of a membrane partially voided of liquid . . air flow of
the partially wetted membrane is equal to 1/2 the dry air flow. (Theoretical
diameter of the mean pore).
MEDIA:
Material through which fluid passes in the
process of filtration and retains particles. Also, nutrients containing
solutions in which cells or microorganisms are grown.
MEDIA MIGRATION:
Migration of materials making up the filter medium may cause contamination of
the filtrate.
MEMBRANE:
Media through which a liquid is passed; usually associated with an extremely
fine or tight type of filtration. Highly engineered polymer film containing
controlled distribution of pores. Used as the separation mechanism in R/O,
Electrodialysis, UF, Nanofiltration & Microfiltration.
MEMBRANE FILTER:
Continuous matrix with pores of
defined size.
MICRON:
The common unit of measurement in the
filtration industry is the micron or micrometer. One micron equals forty
millionths of an inch (0.00004).
MICRON RATING:
The smallest size of particles a filter
can remove.
MICROFILTRATION:
Used for clarification, sterilization, to detect or analyze bacteria and other
organisms and particulate matter. Separation of particles ranging from 0.1mm to
10mm from a fluid by passing the fluid through a membrane.
MICROMETER:
Micron, 1/1,000,000 of a meter. 60gm is approximately the diameter of a human
hair.
MIL:
One thousandth of an inch.
MINIMUM BUBBLE POINT PRESSURE:
It is a diffusional flow pressure just before the onset of bulk flow. Minimum
critical bubble point pressure: a filter specification derived from diffusional
flow, bubble point curves for many filters.
MIXED CELLULOSE ESTERS:
Synthetic materials derived from
naturally occurring cellulose. Materials used in the manufacture of membrane
filters. Mixed cellulose esters membranes are used in a wide variety of
applica-tions, such as bacteria concentration in water analysis and air
sampling.
N
NFR:
Non-fiber releasing. A filter which will
not release fibers into the filtrate.
NIOSH:
Develops basic methodology for analytical
test procedures. National Institute of Occupational Safety and Health.
NYLON:
When used as a membrane it is hydrophilic.
A thermoplastic, polymeric material that has high mechanical strength &
compatibility with different kinds of chemicals.
O
OUTLET PRESSURE:
Downstream pressure. Pressure exiting the outlet side of the filter.
Filtration Terminology:
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