In order to understand
terminology used in / on UV disinfection, a summary
of all terms in
alphabetic order is listed below:
Amalgam tubes
Amalgam lamps have been developed recently to overcome
the problems associated with traditional low-pressure
technology. This type of lamp contains a mercury amalgam,
and typically up to 120mg of mercury is contained
in each lamp. The Amalgam lamp is typically very long,
and not unusually can be more than 1.5 m (5 feet)
in length. Once switched on, the Amalgam lamp output
is not effected by water temperature fluctuations,
however the large size of the lamp does mean that
they can take up to 800 seconds to get to full power,
and the warm up time is temperature dependant. These
lamps are monochromatic in output, and only produce
UV light at 253.7nm. Amalgam lamps have typically
a connected power of 300watts, and can have up to
35% efficiency. The lamp life is often below the expected
hours due to failure caused by the filaments becoming
brittle and deposits of mercury oxide causing the
ends to become black. This leads to poor heat dissipation
and is the most probable failure mode.
American National Standards Institute (ANSI)
A consensus organization which coordinates voluntary standards for the physical,
electrical and performance characteristics of electrical and mechanical equipment.
Whereas the ANSI standard is commonly applied in the USA, the JIS standard in Japan /
Asia, the DIN standards can often be found throughout Europe.
Amperes ("Amps")
A measure of electrical current. In incandescent lamps,
the current is related to voltage and power as follows:
Current (Amps) = Power (Watts) / Voltage (Volts).
ANSI Ballast Type
Ballast type used to operate lamp.
ANSI Codes
These are 3-letter codes assigned by the American National Standards Institute. They
provide a system of assuring mechanical and electrical interchange ability among similarly
coded lamps from various manufacturers.
Arc Length
In High Intensity Discharge lamps this is the length of the arc that you can see outside of
the bulb.
Atmosphere
This field designates the type of gas or vacuum the filament operates within. Gas filled
lamps are more efficient than vacuum lamps.
Automatic cleaning mechanism
By applying an automatic cleaning mechanism, the quartz
sleeve(s) inside a UV chamber, which surround the
UV lamp(s) are periodically cleaned on a pre-set time
interval preventing the build-up of deposits. The
cleaning frequency can be changed on demand. A UV
sensor carefully monitors the UV intensity needed
and is able to override the timer of the cleaning
mechanism in case an immediate cleaning action is
required. A built-in motor drives the cleaning mechanism
and its functionality is continuously checked. The
wiper strokes are counted. This information is needed
to determine the service interval of the wiper rings
which require replacement after an extended service
period. An alternative can be found in a manual cleaning
mechanism (see also description: Manual cleaning mechanism).
Ballast
An auxiliary piece of equipment designed to start and to properly control the flow of power
to discharge light sources such as fluorescent and high intensity discharge (HID) lamps.
Some lamps require the ballast to have thermal protection. Alternative to a transformer.
Base or Socket
The type of base or socket.
Base Temperature
The maximum operating temperature of the base in Celsius. Base Temperature Rise
The maximum increase in temperature from ambient temperature to operating
temperature in the base. Biofilm
A formation of biological fouling inside a piping system. Often Biofilm ( also referred to a
biomass) is a layer made up out of aerobe and anaerobe micro organisms. Biofilm
formation is a very common phenomenon. In industries Biofilm is often flushed out with a
CIP protocol, a flushing program to clean the inside of the pipelines.
Bulb Material or Coating
The type of glass (or quartz) used in the glass envelope surrounding the light source. The
material can also have coatings applied to achieve particular performances. Candela (cd)
The international unit (SI) of luminous intensity. The term has been retained from the early
days of lighting when a standard candle of a fixed size and composition was used as a
basis for evaluating the intensity of other light sources. Cathode Resistance
Resistance of the cathode in a Fluorescent lamp. It is measured "cold" before the lamp is
turned on (Rc) or "hot" after the lamp is turned on (Rh). The ratio of the hot resistance to
the cold resistance is also measured (Rh/Rc). Chamber
The chamber, also referred to as the UV chamber is the closed area were the disinfection
by means of UV light actually takes place. This UV chamber should be developed for
optimised UV performance and at the same time have the mechanical optimised variables
for easy, safe and reliable operation. These variables are working pressure, temperature,
corrosion protection, durability, ease of service and maintenance. ChemWeb-server
Nowadays innovative electronic development not only deals with the functions of
measurement and control, but beyond that to data management and remote access.
Continuous remote monitoring of process parameters provides many advantages in all
areas of industry. The general availability of the Internet as a worldwide standard for data
communication plays an important role. By using Web technology the Internet potential of
this worldwide standard can be utilised for process control.
With this infrastructure, access to the ChemWeb-Server is possible from any computer
with Internet access. No proprietary software is required.
The main benefits of the ChemWeb-Server are found in the area of process data
monitoring, routine checks, service and maintenance.
Any time and anywhere in the world, the system allows communication with Wallace &
Tiernan equipment. When you need it, you just connect the unit installed via the RS485
bus to the ChemWeb-Server. The ChemWeb-Server is equipped with all the standard
interfaces required for Internet communication. Access via PC and standard Internet
Browser is therefore always guaranteed. The client-server-structure provides
simultaneous
multiple user access, even via different communication systems. Access is also possible
at the
same time for different actions: system operation, maintenance, establishment of works
schedules, management. Easy and cost-effective access is possible worldwide via a local
Internet service provider. Password protected access provides system security. Chromaticity
Measure to identify the colour of a light source, typically expressed as (x,y) coordinates
on a chromaticity chart. See: Colour Temperature CIP procedure
A CIP procedure is flushing program or protocol to clean the inside of the pipelines. Often
a combination of chemicals, steam and cold water is used to flush the pipes thoroughly
and leave no traces of chemicals inside the pipeline. CIP cleaning procedures are very
commonly applied to in food and soft drink industry and pharmaceutical industry. Colour Temperature
Originally, a term used to describe the "whiteness"
of incandescent lamp light. Colour temperature is
directly related to the physical temperature of the
filament in incandescent lamps so the Kelvin (absolute)
temperature scale is used to describe colour temperature.
For discharge lamps where no hot filament is involved,
the term "correlated colour temperature" is used to
indicate that the light appears "as if" the discharge
is operating at a given colour temperature. Chromaticity
is expressed either in Kelvin's (K) or as "x" and
"y" coordinates on the CIE standard Chromaticity Diagram.
Although it may not seem sensible, a higher temperature
colour (K) describes a visually cooler, bluer light
source. Typical colour temperatures are 2800K (incandescent),
3000K (halogen), 4100K (white), and 5000K (daylight-simulating
fluorescent colours).
Compact Fluorescent Lamp (CFL)
The general term applied to families of smaller diameter fluorescent lamps, some of which
have built in ballasts and medium screw bases for easy replacement of incandescent
lamps. Fluorescent bulbs use approximately 2/3 to 4/5 less electricity than regular incandescent bulbs with comparable lumen ratings and also last 20 times longer. They
produce warm white tones that closely duplicate incandescent light. Cool down time
Total time it takes for a UV lamp after it has been switched off to obtain the right
conditions to be started up again. Current Type (AC/DC)
Whether the operational voltage is based on Alternating Current or Direct Current. DIN
Abbreviation for " Deutsche Industrielle Norm". An institute which develops and sets
standards mainly used for mechanical components. Whereas the ANSI standard is
commonly applied in the USA, the JIS standard in Japan / Asia, the DIN standards can
often be found throughout Europe. Disinfection control
The Wallace & Tiernan installations with medium pressure
UV lamps have the standard feature of controlling
the disinfection process by controlling the UV-output
of the lamps. With the implemented multitap ballast
technology it is possible to control the lamp power
in four steps. A microcomputer takes care of automatic
and autonomic disinfection control.
If the UV-intensity comes below the level that is
3% higher than the UV-alarm level it will start the
"level-up" routine.
Before a higher UV-output level is activated the disinfection
control function first activates the automatic cleaning
mechanism, if available, for optimum system efficiency.
The disinfection control offers flexibility in the
following situations:
* increasing the economical lamp life by selecting
a higher power level of the UV-lamp;
* responding on changes in transmission. Small changes
will automatically correct the power level due to
measured intensity changes. With larger changes in
transmission the setting of the installation can be
changed as long as they stay within the working range
of the system;
* changing bacteriological requirements. Other demands
can be corrected by changing the settings as long
as they are in the working range of the system;
* capacity changes can be adapted within the working
range of the system;
* fouling quartz sleeves can be cleaned by a cleaning
mechanism if available. In case of no cleaning mechanism
or in case a rather strong deposit build-up is experienced
the disinfection control can increase the service
interval.
Dark light reactivation
Some ultraviolet (UV) treated micro organisms can be reactivated without light exposure.
This phenomenon is known as dark light reactivation. Possible damage on the DNA due
to the exposure of the UV light can be repaired by enzymes and proteins within the micro
organism. Dark light reactivation is only applicable for a small group of micro organisms
and, in practice, is to be looked upon as a unusual occurrence.
DNA
Desoxyribonucleic acid (DNA) is the genetic material present in all organisms, from
bacteria to humans. A single subunit of DNA is called a nucleotide and consists of a
nitrogen-containing base, a sugar, and a phosphate group. Hundreds of thousands of
nucleotides are hooked together to form a chain, and two chains are paired together and
twisted into a double helix to form the finished DNA molecule. In organisms with
nucleated cells such as humans, DNA is coupled with protein in structures called
chromosomes that are contained within a membrane-bound nucleus inside a cell.
Dose
The result of the intensity (mW) and the retention time (s) In order to inactivate micro
organisms by means of exposure to UV-C light each micro organism needs a certain
amount of dose. Dose is generated by exposure time to the UV light and intensity (
staying time in the irradiation chamber) in a linear relation. Twice the dose will result in
twice the germicidal effect, three times the dose in three times the germicidal effect etc.
Note that the term Dose is still used and accepted but the preferred terminology here is
the word "Fluence" ( See description)
Drain
Access point on the bottom of the irradiation chamber, which is used to empty the
chamber from water. Draining a chamber is often necessary before a service onto the UV
chamber can take place.
Electromagnetic Spectrum
A continuum of electric and magnetic radiation that can be characterized by wavelength
or frequency. Visible light encompasses a small part of the electromagnetic spectrum in
the region from about 380 nanometers (violet) to 770 nanometers (red) by wavelength.
Electronic Ballast
A short name for fluorescent high frequency electronic ballast. Electronic ballasts use
solid state electronic components and typically operate fluorescent lamps at frequencies
in the range of 25-35 kHz. The benefits are: increased lamp efficacy reduced ballast
losses and lighter, smaller ballasts compared to electromagnetic ballasts. Electronic
ballasts may also be used with HID lamps, but the circuits are quite different.
Fluence
The light dose or fluence is the total radiant energy of all wavelengths passing from all
directions through an infinitesimally small sphere of cross-sectional area. It is given by the
average fluence rate times the exposure time in seconds. The term UV dose is often used
in UV disinfection literature. It represents the UV exposure of a given organism in the
germicidal range. Many authors have used the units mWs cm2, but the equivalent mJ cm2
is preferred. Fluence is the emitted amount of UV light by the UV tubes whereas UV dose
is the received amount of UV light by a micro organism from the UV tubes. Fluence is the
more correct term and is preferred over the word dose ( see also description of "Dose")
Frequency
The stated operating frequency in Hz of a unit.
Halogen Lamp
A short name for the tungsten-halogen lamp. Halogen lamps are high pressure
incandescent lamps containing halogen gases such as iodine or bromine, which allow the
filaments to be operated at higher temperatures and higher efficacies. A higher
temperature chemical reaction involving tungsten and the halogen gas recycles
evaporated particles of tungsten back onto the filament surface.
High-Intensity Discharge (HID) Lamp
A general term for mercury, metal halide lamps. HID lamps contain compact arc tubes,
which enclose various gases and metal salts operation at relatively high pressures and
temperatures.
Hot Restart Time
Time it takes for a High Intensity Discharge lamp to reach 90% of light output after going
from on to off to on.
Illuminance
The "density" of light(lumens/area) incident on a surface. Illuminance is measured in footcandles
or lux.
Incandescent Lamp
A light source which generates light using a thin filament wire (usually tungsten) heated to
white heat by an electric current passing through it.
Infrared Radiation
Electromagnetic energy radiated in the wavelength range of about 770 to 1106
nanometers. Energy in this range cannot be seen by the human eye, but can be sensed
as heat by the skin.
Instant Start
A type of fluorescent lamp-ballast circuit designed to start fluorescent lamps as soon as
the power is applied. Originally, instant-start circuits were developed to eliminate separate
mechanical starter devices. Slimline fluorescent lamps operate only on instant start
circuits.
IP rating ( IP classification)
The IP level is a coding system made up in accordance with the official European
standard, NEN 2433.
The coding consists of two figures which provide information on the possible penetration
of solid material (first figure) and the possible penetration of water (second figure)
The higher the figure, the better the protection is against solid material and / or water.
JIS
Abbreviation for "Japanese Industrial Standards ". An institute which develops and sets
standards mainly used for mechanical and electrical components. Whereas the ANSI
standard is commonly applied in the USA, the DIN standard in Europe, the JIS standards
can often be found throughout Japan / Asia
Kilowatt Hour (kWh)
The standard measure of electrical energy and the typical billing unit used by electrical
utilities for electricity. A 100-watt lamp operated for 10 hours consumes 1000 watt-hours
(100*10) or 1 kilowatt-hour. If the utility charges $.10/kWh, then the electricity cost for the
10 hours of operation would then be 10 cents (1*$.10).
Lamp
The term used to refer to the complete light source package including the inner parts as
well as the outer bulb or tube. "Lamp," of course, is also commonly used to refer to the
type of small light fixture such as a table lamp.
Light
Radiant energy which can be sensed or seen by the human eye. Visible light is measured
in lumens.
Low pressure UV lamp
A UV lamp which emits monochromatic light with an internal pressure of less than 1 bar.
These lamps have a low surface temperature.
Lumen
The international unit of luminous flux or quantity of light.
Lux (lx)
The international unit of illuminance. One lux is equal to one lumen per square meter.
Manual cleaning mechanism
The manual cleaning mechanism is an effective yet simple tool, which has been
developed for cleaning the quartz sleeve effectively inside a UV disinfection chamber. The
cleaning frequency depends on the water quality. An alternative can be found in an
automatic cleaning mechanism (see also description: Automatic cleaning mechanism)
Mercury Lamp
A high-intensity discharge light source in which the light is produced by the radiation from
mercury, plus halides of metals such as sodium, scandium, indium and dysprosium.
Some lamp types may also use phosphor coatings.
Medium pressure UV lamp
A UV lamp which emits polychromatic light with an internal pressure slightly higher than 1
bar. These lamps have a high surface temperature.
Nanometer
A unit of wavelength equal to 10-9 meters.
PFAS
Abbreviation for Potential Free Alarm Signal. In case of an alarm on the unit a signal is
offered which can be used to sound an acoustic alarm, phone to a mobile phone, close a
valve, shut off the power or whatever adequate follow is needed.
Phosphor
An inorganic chemical compound processed into a powder and deposited on the inner
glass surface of fluorescent tubes and some mercury and metal-halide lamp bulbs.
Phosphors are designed to absorb short wavelength ultraviolet radiation and to transform
and emit it as visible light.
PT 100 temperature detector
PT 100 is the abbreviation for Platinum Thermistor 100. This is a commonly and widely
used type of temperature monitor in industrial equipment to check the temperature. PT
100 temperature detectors are extremely reliable and accurate.
Photoreactivation
Ultraviolet (UV) treated micro organisms can be reactivated with light exposure. This
phenomenon is known as Photoreactivation. Possible damage on the DNA due to the
exposure of the UV light can be repaired by enzymes and proteins within the micro
organism.
Quartz
A high purity material commonly used for the protective jacket which surrounds the UV
tube. Quartz is UV transparent and can withstand high pressures and high temperatures.
(This makes the material ideal for protection of the UV tubes) Pending on the type of
quartz one can block undesired wavelengths. Typical filter blocks are at 180nm ( to block
ozone generating radiation), 200 to 220 nm ( to block nitrite formation)
Sensor
A monitor tool used to check if a preset intensity level ( directly related to the UV dose) is
maintained. A UV sensor can commonly be found on the outside of a chamber wall and is
pointed toward one or a cluster of UV tubes. UV light enters the sensor and, after possible
filtering and screening, falls on a photodiode. Here the intensity is measured of the
amount of light present. Normally a UV sensor gives a relative value which implies that
calibration of the sensor is an important procedure in order to receive values which can be
used and calculated with. If a preset value is not achieved, commonly an alarm is
triggered.
Temperature detector
See: PT 100 temperature detector.
Total dissolved solids (TDS)
Concentration of all substances dissolved in water
(solids remaining after evaporation of a water sample).
Transformer
An auxiliary piece of equipment, which works with capacitors, designed to start and to
properly control the flow of power to discharge the UV light sources. Alternative to a
ballast.
Transmission
The penetration of the fluid for UV-C light.
Organic, inorganic substances and acids present in
the fluid absorb UV-C light. This absorption causes
UV-C light emitted by a centrally placed UV tube to
diminish. Pending on the amount of substances this
diminishing effect is variable. To asses this effect
the term "transmission" is used. Per definition demineralised
water has a transmission of 100%. At this level non
of the emitted light is absorbed by the substances
in the fluid. At higher levels of absorption the transmission
reduces. The transmission level can be given in various
scales. Currently following scales are used: T10,
T40, T50 and T100 all given in mm. A value given T10mm
scale gives the absorption over 10mm of the fluid.
Example: A T10 of 88% means that after travelling
a distance of 10mm through the fluid from the original
100% of UV-C light only 88% is still present. In the
second layer of 10mm we then start with 88% and from
this value only 88% remains. This means that a T10mm
of 88% equals a T20mm of (88 x 88) = 77% The T40mm
value here would be ( 88 x 88 x 88 x 88) = 60%
Tri Halo Methane (THM)
Tri Halo Methane (THM) are possible carcinogenic by-products which can be formed
when organic material in water reacts with chloramines. These THM's can be formed
when chlorine is used as disinfectant of the water. To minimise the THM formation one
can try to filter out the organic load in the water and / or minimise the amount of chlorine
in the water. By means of using UV disinfection in a water treatment process instead of /
or in conjunction with chlorine disinfection one can reduce the THM level in the water after
the treatment station.
Turbidity
A suspension of fine particles that obscures light rays but requires many days for
sedimentation because of the small particle size.
Ultraviolet (UV) disinfection
A technology were by means of emittance of ultraviolet light into a medium, inactivation of
micro-organisms is acquired. This UV light will penetrate through the cell wall and will be
absorbed by the DNA material. Ultraviolet disinfection is a technology which can be
applied for disinfection of air, water and surfaces.
Ultraviolet (UV) Radiation
Radiant energy in the range of about 100-380 nanometers (nm). For practical
applications, the UV band is broken down further as follows:
Ozone Producing: 180 - 220nm
Bactericidal (germicidal): 220 - 300 nm
Erythemal (skin reddening): 280 - 320 nm
"Black" light: 320 - 400 nm
The International Commission on Illumination (CIE) defines the UV bands as UV-A (315-
400nm); UV-B (280 - 315 nm) and UV-C (100-280). "%UV_ Reduction" is the percentage
of the particular band of UV light that is reduced.
UV chamber
See: Chamber.
UV sensor
See: Sensor.
Wall Temperature
The maximum operating bulb wall temperature in Celsius.
Warm Up Time to 90%
The time it takes for a High Intensity Discharge lamp to reach 90% of light output after
being turned on.
Watt
A unit of electrical power. Lamps are rated in watts to indicate their power consumption.
Power consumed over time equals the electrical energy used.
Wiper mechanism
A mechanism that cleans the outside of the quartz jacket, which surrounds a UV tube,
from dirt and other fouling. A wiping mechanism can be executed in a hand operated
system or a fully automated system were. In an automatic wiping mechanism a motor is
commonly used to trigger the movement.
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