44
TB 210 IR_2a 01/2015
Degassing – removal of bubbles
Note: Do not use with T-Cal Standards
If the Turbidity is low it is important to remove air bubbles from the sample, using one
or a combination of the following methods:
• Addition of a surfactant
• Application of a partial vacuum
• Application of heat
• Use of an ultrasonic bath
Note:
This procedure can influence the nature of the sample and therefore the turbidity reading.
Type of
sample
Method
Description of the
method
Notes:
Samples
oversaturated
with air
Addition of a surf-
actant
Surfactants minimise
the surface tension
of a sample, allowing
entrained gases to
disappear.
Particles in the sample
settle more rapidly, so
the sample must be
swirled before being
measured.
Avoid vigorous shaking
as this causes the surf-
actant to foam.
Liquid
samples
without
readily volatile
components
Use of a partial
vacuum
A vacuum can be crea-
ted with the help of a
clean, oil-free syringe
or pump fitted onto
a vial.
The vacuum reduces
the atmospheric pres-
sure, so that trapped
air bubbles can be
removed.
Volatile components
can escape from the
sample.
The vacuum may com-
pound the air bubble
problem in viscous
samples.
Viscous
samples
Use of an ultrasonic
bath
The ultrasonic waves
excite the sample,
effectively removing
air bubbles from most
samples.
Ultrasonic waves can
change the particle
size in the sample,
therefore changing the
turbidity.
Very viscous
samples
Heating the sample
Heating the sample
makes it less viscous,
air bubbles can disap-
pear more easily.
The sample has to cool
to its original tempe-
rature.
Volatile components
can disappear from the
sample. The attributes
of suspended particles
change, therefore
changing the turbidity.
GB
Measurement techniques
Содержание Lovibond TB210 IR
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