Specifications

About Colorimetric Measurement
Introduction to Colorimetry
Colorimetry is defined as the measurement of a parameter whose
concentration is proportional (directly or inversely related) to color
intensity after the addition of known volume of reagent(s).
Different chemical substances absorb different and varying visual
light frequencies. Since the absorbance of a substance is proportional
to its concentration i.e., a more concentrated solution gives a higher
absorbance reading, therefore the concentration of a known solute can
be measured using a colorimeter.
Eutech’s latest range of handheld waterproof colorimeters measure
chlorine (free and total), cyanuric acid, pH, chlorine dioxide, bromine
and ozone. The applications include water analysis in swimming
pools, spas, public utilities, industrial wastewater plants, municipal
water, treated water, water conditioning systems and paper and
pulp mills.
The eectiveness of the disinfectants used depends on your system’s
overall water chemistry, and not just on the disinfectants’ concentrations
alone. The following section provides a brief overview on the
measurement of each parameter:
Bromine
Bromine is often used as a disinfectant in indoor or covered water systems.
Due to lower volatility, bromine is more stable in water than chlorine.
Compared to chlorine, the main advantages of bromine are reduced
odour, and skin and eye irritation. In addition, bromine remains eective
at high temperatures and its disinfecting eciency is not aected by pH
uctuations. The disadvantages are that bromine is more expensive than
chlorine and it cannot be stabilised for outdoor use.
Eutech’s C 104 colorimeter measures bromine over the range of
0 ppm to 13.5 ppm.
Chlorine
Chlorine and chlorine-release compounds are frequently used as
disinfectants in swimming pools, drinking water and other water
treatment systems. Routine chlorination kills harmful micro-organisms.
The disinfection eciency is a direct function of the level of free chlorine
in a system. Total chlorine is the sum of combined and free chlorine.
In applications where there is human contact with the water e.g. in
swimming pools and spas, it is essential that the right amount of chlorine
is present. Insucient chlorine will decrease the disinfectant eciency;
while excess chlorine will cause skin and eye irritation and become a
health hazard.
Eutech’s C 401, C 301 and C 201 colorimeters measure free and total
chlorine over the range of 0 mg/L to 6 mg/L.
Chlorine Dioxide
The use of chlorine dioxide as a disinfectant is seeing growth in many
industrial applications. Unlike chlorine, chlorine dioxide remains a true
gas dissolved in solution. The lack of any signicant reaction of chlorine
dioxide with water is partly responsible for its retaining its disinfecting
eectiveness over a wide pH range. This property makes it a logical choice
for cooling systems operated in the alkaline pH range, or cooling systems
with poor pH control. Other applications for chlorine dioxide include the
food processing industry; the pulp and paper industries, and the potable
water and waste treatment industries.
Eutech’s C 103 colorimeter measures chlorine dioxide over the
range of 0 ppm to 11.4 ppm.
Ozone
Ozone is one of the strongest and most rapid oxidisers and disinfectants
available. Ozone does not require any stabiliser. It does not corrode nor
cause scaling. In addition, ozone has no smell, does not cause skin nor eye
irritation and does not pose a health hazard. Although more expensive
than traditional disinfectants like chlorine and bromine, because it
does not cause corrosion nor scaling, the long-term maintenance cost
of a water system which uses ozone as a disinfectant may be reduced
compared to using chlorine. Ozone is gaining popularity in top spas and
certain swimming pools.
Eutech’s C 105 colorimeter measures ozone over the range of
0 ppm to 4.1 ppm.
Cyanuric Acid
In applications where chlorine is used for disinfection, cyanuric acid
is often present as a chlorine stabiliser. Low levels of cyanuric acid are
benecial as they prevent wastage of free chlorine by the sun’s UV rays.
High levels of cyanuric acid cause the chlorine to take a longer time
to kill the micro-organisms. It is important to test your water sample
to determine how much cyanuric acid should be added to maximise
chlorine eciency.
Eutech’s C 401 and C 102 colorimeters measure cyanuric acid over
the range of 5 ppm to 90 ppm.
pH
The pH value aects the amount of free chlorine that is formed, and
therefore determines the eectiveness of chlorine as a disinfectant. As
pH increases, the disinfecting power of chlorine decreases. High pH
causes scaling of water surfaces, pipework and ttings; this may result in
cloudy water. Low pH can corrode metals in pipework and ttings; this
may cause metal oxides to stain water surfaces.
Eutech’s C 401, C 301 and C 101 colorimeters measure pH over the
range of 5.9 - 8.2.
Colorimetry | About Colorimetric Measurement
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