Aquaprobe
®
Lite Instruction Manual
10401-00976 Rev F
11.1. Top Tips for successful measurements using optical electrodes
Always keep the measurement chamber and electrode lenses clean.
Always fit the sleeve and end cap during both calibration and measurement.
Always allow the readings to settle completely during both calibration and
measurement.
Always try to eliminate air bubbles by agitating the Probe after insertion both during
calibration and measurement.
Always calibrate and zero the electrode as close to your sample temperature as
possible. This is especially important with the Ref-Oil electrode.
Always zero the electrode just prior to use in clean water (bottled still mineral water is
ideal). This is also especially important with the Ref-Oil electrode.
11.2. Electrode Calibration Sequence
Optical electrodes feature either two or three point calibration, dependent upon the type. In
all cases however, the lower calibration points is ZERO.
When calibrating any optical electrode,
the Zero point must be calibrated first.
If you are performing a two or three point calibration, all calibration points must be
calibrated within the same calibration session (i.e. without turning the Aquameter
®
off or
disconnecting the Aquaprobe).
If you attempt to calibrate an upper calibration point without first calibrating the
ZERO point, a calibration error will occur.
11.3. 2000-TURB Turbidity Electrode
Turbidity can be measured by the AP-Lite using the optional 2000-TURB optical electrode.
This electrode employs a Nephelometric technique in accordance with ISO 7027, which
uses Formazin as a reference standard. The Aquameter
®
displays turbidity in
Nephelometric Turbidity Units (NTU) which are nominally equivalent to Formazin Turbidity
Units (FTU).
Turbidity can be calibrated with either Formazin Turbidity Standards or Suspended Polymer
Turbidity Standards, depending upon your preferred turbidity reference.
Be aware, these
two standards will give very different results
. Factory calibration is carried out with a
1000 NTU Stabilised Formazin Turbidity Standard in accordance with ISO 7027.
11.3.1.
About Turbidity
Turbidity is a measurement of the light scattering properties of solids suspended within a
liquid and is therefore an
indirect
measurement of clarity. Turbidity is not a direct
measurement of suspended solids, clarity or colour.
Particle size relative to the wavelength of the transmitted light, particle shape and refractive
index modify the distribution of scattered light. Sample colour, (particularly dark colours)
can also reduce a certain portion of the scattered light by varying degrees.
© 2015 Aquaread
®
Ltd.
www.aquaread.com
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