GLOSSARY
# A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
A
Aerosol -
A suspension in a gaseous medium of solid particles,
liquid particles or
solid
and liquid particles having negligible falling velocity.
AFLP
Amplified
Fragment
Length
Polymorphisms - A
highly sensitive method for detecting
polymorphisms in DNA.
Following
restriction enzyme digestion of DNA,
a subset of DNA fragments
is
selected for PCR amplification and
visualisation.
Air-conditioning - A form of air treatment whereby
temperature humidity and air cleanliness
are all controlled within limits
determined by the requirements of
the air-conditioned enclosure.
Algae - A small, usually aquatic, plant
which requires light to grow, often
found on exposed areas of cooling
towers.
Amoebae - Protozoa able to alter shape as
a result of movements of cell processes.
Protozoa generally live in fresh
water, soil or as parasites in humans
and animals. Some amoebae can ingest
Legionella allowing them to replicate
in a protected environment.
Antibodies - Substances in the blood which destroy
or neutralise various toxins or components
of bacteria known generally as antigens.
The antibodies are formed as a result
of the introduction into the body
of the antigen to which they are
antagonistic as in all infectious
diseases.
Anti-Corrosive
Chemicals - Also known as corrosion
inhibitors. Chemicals which protect
metals by: (a) passivating the metal
by the promotion of a thin metal
oxide film (anodic inhibitors); or
(b) physically forming a thin barrier
film by controlled deposition (cathodic
inhibitors).
Anti-Stratification
Pump – Another name for Shunt Pump
(see below)
Artificial
Water
Systems - Any water system
that has been constructed and does
not
occur naturally such as a hot water
system.
Audits - See also Legionella audits. The
inspection and verification of an
existing Legionella risk management
system. This would normally involve
the review of existing Legionella
risk assessment reports and other
documentation to ensure all critical
risks are addressed and action plans
are operational.
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B
Bacteria -
(singular bacterium) a microscopic,
unicellular
(or more rarely multicellular) organism.
Biocides - A substance which kills micro-organisms.
Biodispersants - A chemical product that can be
added to recirculating water within
a cooling system to penetrate and
break down biofilms.
Biofilm - A community of bacteria and other
micro-organisms, embedded in a protective
layer with entrained debris, attached
to a surface.
Blow-Down/Bleed-Off - Water discharged from the system
to control the concentration of salts
or other impurities in the circulating
water; usually expressed as a percentage
of recirculating water flow.
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C
Calorifier -
An apparatus used for the transfer
of
heat to water in a vessel by indirect
means,
the source of heat being contained
within
a pipe or coil immersed in the water.
CFU
or
Colony Forming Units - A unit
of measurement used in microbiology
that indicates the number of microorganisms
present in a water sample. It is
normally measured by the number of
colony forming units (CFU) present
in one millilitre of water.
Chlorine - An element used in disinfection.
Cold
Water
Service (CWS) - Installation
of plant, pipes and fitting in which
cold water is stored, distributed
and subsequently discharged.
Concentration
Factor - Compares the level of dissolved
solids in the cooling water with
that dissolved in the make-up water
(also known as cycle of concentration).
Usually determined by comparison
of either the chloride or magnesium
hardness concentration.
Cooling
Tower - An apparatus through which
warm water is discharged against
an air stream; in doing so part of
the water is evaporated to saturate
the air and this cools the water.
The cooler water is usually pumped
to a heat exchanger to be reheated
and recycled through the tower.
Corrosion
Inhibitors - Chemicals which protect
metals by: (a) passivating the metal
by the promotion of a thin metal
oxide film (anodic inhibitors); or
(b) physically forming a thin barrier
film by controlled deposition (cathodic
inhibitors). See anti-corrosion chemicals
above
Coliform
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D
Dead
End/Blind
End - A length of pipe
closed
at one end through which no water
passes.
Deadlegs - Pipes leading to a fitting through
which water only passes when there
is draw-off from the fitting.
Decontamination - The
process of removing or neutralising
pathogenic
bacteria in a water or other system.
Dipslides - A dipslide is a means of testing
the microbial content of liquids.
It consists of a plastic carrier
bearing a sterile culture medium
which can be dipped in the liquid
to be sampled. It is then incubated
to allow microbial growth. The resulting
microbial colonies are estimated
by reference to a chart.
Disinfection - A process which destroys or irreversibly
inactivates micro-organisms and reduces
their number to a non-hazardous level.
Distribution
Circuit - Pipework which distributes
water from hot or cold water plant
to one or more fittings/appliances.
Domestic
Water
Services - Hot and cold water
intended for personal hygiene, culinary,
drinking water or other domestic
purposes.
Drift - Circulating water lost from the
tower as liquid droplets entrained
in the exhaust air stream; usually
expressed as a percentage of circulating
water flow but for more precise work
it is parts of water per million
by weight of air for a given liquid
to gas ratio.
Drift
Eliminator - More correctly referred
to as drift reducers or minimisers
– equipment containing a complex
system of baffles designed to remove
water droplets from cooling tower
air passing through it.
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E
e.coli
Evaporative
Condenser - A heat exchanger in which
refrigerant is condensed by a combination
of air movement and water sprays
over its surface.
Evaporative
cooling - A process by which a small
portion
of
a circulating body of water is caused
to evaporate thereby
taking
the required
latent
heat of vaporisation from the remainder
of the water and
cooling it.
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F
Fill/Packing -
That portion of a cooling tower which
constitutes its primary heat
transfer
surface; sometimes called ‘packing’
or ‘pack’.
Flushing - The process of draining and cleaning
a cooling system, including all associated
pipework.
Fouling - Organic growth or other deposits
on heat transfer surfaces causing
loss in efficiency.
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H
Half-Life -
Ratio of system volume to purge rate.
Hot
Water
Services (HWS) - Installation
of plant, pipes and fittings in which
water is heated, distributed and
subsequently discharged (not including
cold water feed tank or cistern).
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L
Legionaires’
Disease - A misspelling, more correctly
spelt
Legionnaires' disease which is a
form of pneumonia caused by
Legionella
bacteria.
Legionella - Type of aerobic bacterium which
is found predominantly in warm water
environments. (singular of legionellae).
Legionella
Audits - The inspection and verification
of an existing Legionella risk management
system. This would normally involve
the review of existing Legionella
risk assessment reports and other
documentation to ensure all critical
risks are addressed and action plans
are operational
Legionella
Bacteria - (singular bacterium) a
microscopic, unicellular (or more
rarely multicellular) organism. The
germ which causes Legionnaires' disease
is a bacterium called Legionella
pneumophila.
Legionella
Bacterium - (plural bacteria) a microscopic,
unicellular
(or more rarely multicellular) organism.
The germ which causes Legionnaires'
disease
is a bacterium called Legionella
pneumophila.
Legionella
Bacterium - (plural bacteria) a microscopic,
unicellular
(or
more
rarely multicellular) organism. The
germ
which causes Legionnaires' disease
is
a bacterium
called Legionella
pneumophila.
Legionella
Disease - A name sometimes used
to describe Legionnaires' disease.
Legionnaires' disease is a form
of pneumonia caused by Legionella
bacteria. Legionella is a type
of aerobic bacterium which is found
predominantly in warm water environments
(singular of legionellae).
Legionellae - The genus legionella belongs to
the family legionellaceae which has
over 40 species. These are ubiquitous
in the environment and found in a
wide spectrum of natural and artificial
collections of water.
Legionella
Longbeachae - One of the causative
organisms of Legionnaires’ disease.
Has also been associated with soil,
potting compost, mulches, compost
heaps and composted animal manures.
Particularly common in Australia
although cases have been reported
in other countries including the
USA and Japan.
Legionella
Pneumonia - Legionnaires' disease
is
a type of pneumonia. It was named
after
an outbreak of severe pneumonia which
affected a meeting of the American
Legion
in 1976. The germ which causes
Legionnaires'
disease is a bacterium called Legionella
pneumophila.
Legionella
Pneumophila - One of the causative
organisms of Legionnaires’ disease.
Legionella
Pneumophilia - A misspelling, more
correctly
spelt Legionella pneumophila which
is one of the causative organisms
of
Legionnaires’ disease.
Legionella
Micdadei - The second most commonly
isolated member of the Legionella
family. The bacterium can cause flu
like symptoms and pneumonia, including
Pittsburgh pneumonia.
Legionella
Sampling - Any monitoring programme
should include routine sampling and
testing for the presence of bacteria,
both general (aerobic) bacterial
species and Legionella bacteria.
Detection of Legionella bacteria
requires specialist laboratory techniques,
although routine monitoring for aerobic
bacteria can be used as an indication
of whether microbiological control
is being achieved.
Legionella
Species – Currently there are at
least 46 species and 70 serogroups
of Legionella as follows:
Legionella
adelaidensis
|
Legionella
anisa
|
Legionella
beliardensis
|
Legionella
birminghamensis
|
Legionella
brunensis
|
Legionella
busanensis
|
Legionella
cherrii
|
Legionella
cincinnatiensis
|
Legionella
donaldsonii
|
Legionella
drancourtii
|
Legionella
drozanskii
|
Legionella
erythra
|
Legionella
fairfieldensis
|
Legionella
fallonii
|
Legionella
feeleii
|
Legionella
geestiana
|
Legionella
gratiana
|
Legionella
gresilensis
|
Legionella
hackeliae
|
Legionella
israelensis
|
Legionella
jamestowniensis
|
Legionella
jordanis
|
Legionella
lansingensis
|
Legionella
londiniensis
|
Legionella
longbeachae
|
Legionella
lytica
|
Legionella
monrovica
|
Legionella
moravica
|
Legionella
nautarum
|
Legionella
oakridgensis
|
Legionella
parisiensis
|
Legionella
pneumophila
|
Legionella
quateirensis
|
Legionella
quinlivanii
|
Legionella
rowbothamii
|
Legionella
rubrilucens
|
Legionella
sainthelensi
|
Legionella
santicrucis
|
Legionella
shakespearei
|
Legionella
spiritensis
|
Legionella
steigerwaltii
|
Legionella
taurinensis
|
Legionella
tucsonensis
|
Legionella
wadsworthii
|
Legionella
waltersii
|
Legionella
worsleiensis
|
Legionellosis - Any illness caused by exposure to legionella.
Legionnaires’ Disease - A form of pneumonia caused by Legionella bacteria.
Lochgoilhead fever – An illness similar to legionnaires’ disease caused
by a species of legionella called Legionella micdadei. Was so called after
an outbreak in Lochgoilhead, Scotland The incubation can be up to 9 days. A
high percentage of those exposed to this agent tend to be affected. There have
been no recorded deaths associated with Lochgoilhead fevers.
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M
Make-Up
Water - Water which is added to a cooling water system to compensate
for wastage (e.g. via system leaks), evaporative loss and bleed.
Micro-Organism - An organism of microscopic size including bacteria, fungi
and viruses.
Multi-Locus Sequence Typing - A method of molecular typing, relying on
DNA sequence analysis of nucleotide polymorphisms in several genes. This technique
has shown a high degree of intra-species discriminatory power for bacterial
and fungal pathogens.
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N
Non-Oxidising
Biocide - A non-oxidising biocide is one that functions
by mechanisms other than oxidation, including interference with cell metabolism
and structure.
Nutrients - A food source for micro-organisms.
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O
Oxidizing
Biocides - Agents capable of oxidizing organic matter, eg cell
material, enzymes or proteins which are associated with microbiological populations
resulting in death of the micro-organisms. The most commonly used oxidizing
biocides are based on chlorine or bromine (halogens) which liberate hypochlorous
or hypobromous acids on hydrolysis in water. The exception is chlorine dioxide,
a gas which does not hydrolyse but which functions in the same way.
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P
Parts
Per Million (ppm) - a measure of dissolved substances given as the
number of parts there are in a million parts of solvent. It is numerically
equivalent to milligrams per litre mg/l with respect to water.
Pasteurisation - Heat treatment to destroy micro-organism usually at high
temperature.
PCR - Polymerase chain reaction.
Phenotypic Variations - Differences in the expression of genes as determined
by observable characteristics such as the presence or absence of a particular
cell component.
Planktonic - Free floating micro-organisms in an aquatic system.
Plume - The visible discharge of air and moisture from a cooling tower
or other scooling system. This can include condensation and aerosols and as
such represents a potential Legionella risk.
Pond/Sump - Collection of cooling water at the base of a cooling tower.
Pontiac Fever - A disease caused by species of legionella, an upper respiratory
illness less severe than Legionnaires’ disease. There have been no recorded
deaths associated with Pontiac.
PPE - Personal Protective Equipment. Used to protect personnel during
hazardous operations.
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R
Retention
Time - Time a chemical is retained in the system.
Risk Assessment - Identifying and assessing the risk from legionellosis
from work activities and water sources on premises and determining any necessary
precautionary measures.
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S
Scale -
Crystalline deposits that form on system surfaces or pipework. Scale normally
results from a build up of unwanted minerals, usually calcium
carbonate. See also scale inhibitors.
Scale Inhibitors - Chemicals used to control scale. They function by holding
up the precipitation process and/or distorting the crystal shape, thus preventing
the build-up of a hard adherent scale.
Sediment
Sentinel Taps - For a hot water services – the first and last taps on
a recirculating system. For cold water systems (or non-recirculating hot water
systems), the nearest and furthest taps from the storage tank. The choice of
sentinel taps may also include other taps which are considered to represent
a particular risk.
Sero-Group - A sub-group of the main species. Serogroups are groups of
microorganisms only differing by their composition in terms of antigens.
Sessile - Aquatic micro-organisms adhering to a surface normally as part
of a biofilm.
Shunt Pump - A circulation pump fitted to hot water service/plant to overcome
the temperature stratification of the stored water. Water should be circulated
from the hot zone to the cool zone which is normally from the top to the base
of the calorifier.
Slime - A mucus-like exudate which covers a surface produced by some micro-organisms.
Sludge - A general term for soft mud-like deposits found on heat transfer
surfaces or other important sections of a cooling system. Also found at the
base of calorifiers and cold water storage tanks.
Spa Pools - A spa pool is a self-contained body of warm water designed
for sitting in (not whole body immersion). It is intended for a small number
of people to use at one time. The water is re-circulated and kept between 30
- 40 oC and is usually not drained between use and is continually filtered
and cleaned. A hydro-jet circulation, with or without an air induction bubble
system, is also used to agitate the water.
Spa pools are known under a range of names – spa bath, hot spa, hot tub, portable
spa, whirlpool spa, swim spa and often Jacuzzi. All systems usually work
in the same way.
Spray Drift - Aerosol emissions from cooling towers due to fan forced or extracted
air exiting the cooling system or tower. This can include condensation and
aerosols and as such represents a potential Legionella risk.
Stagnation - The condition where water ceases to flow and is therefore
liable to microbiological growth.
Strainers - A coarse filter usually positioned upstream of a sensitive
component such as a pump control valve or heat exchanger to protect it from
debris.
Surfactants - Soluble surface acting additives that help to reduce the
surface tension between water and particulate matter.
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T
Thermal
Disinfection - Heat treatment to disinfect a system. See also
Pasteurisation
Thermostatic Mixing Valves - Mixing valve in which the temperature at the outlet
valve is pre-selected and controlled automatically by the valve. These should
be of the automatic type where the hot water automatically shuts off if the
cold water fails.
Total Viable Counts (TVC) - The total number of culturable bacteria (per
volume or area) in a given sample (does not include legionella).
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W
Windage -
Physical loss of water from a cooling tower caused by draught of air or wind
– water is lost around the base of the cooling tower as a result
of cross winds as opposed to drift.
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