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3. Notes on Turbidity Probes & Standards
The probes designed to operate with the NEP160 display units are "smart probes"
in that they each carry their own "signature", that is, calibration and
characterisation data. Consequently, probes can be connected to any
WP-89
and
the display unit is immediately informed of the necessary calibration constants
for proper operation. This allows the operator to use more than one probe with
the same display unit. Further, probes can be periodically factory-calibrated
without the need to return the
WP-89
instrument to the factory also.
On power up the
WP-89
will interrogate the probe socket to determine if a probe
is connected, and its parameters. If a probe is not connected the display will show
the message "
NO PROBE
". After successful interrogation of a probe, the display
will show the message "
probe s/n 12345
" for a short period, where
"
12345
" is the probe's serial number. This confirms successful communication
with the probe. Probes may be changed over at any time. Immediately after
another probe is connected, the display will indicate the serial number of the new
probe to show proper communication has taken place and the
WP-89
has the
necessary probe information for accurate readings.
Two Turbidity probes are available for use with the
WP-89
. They are…
High Sensitivity Probe, Part No 125192
High sensitivity turbidity probe measuring light scattered at 90
O
according to
ISO7027. It is capable of measuring Turbidity from 0 to 3,000 NTU. This probe
can be submersed to a depth of 30m. Standard cable length is 5m, but other
lengths can be specified at order.
Wide Range Probe, Part No 125194
General purpose retro-scatter probe that measures light reflected back at 180
O
. It
is capable of measuring Turbidity from 10 to 30,000 NTU. This probe can be
submersed to a depth of 30m. Standard cable length is 5m, but other lengths can
be specified at order.
Primary and Secondary Turbidity Standards
Primary Turbidity standards, as the name suggests, are formulated from primary
materials. They are not diluted in any way and are recommended for users who
require utmost accuracy. Primary standards should be used if Turbidity readings
are to form the basis of legal proceedings.
Secondary Turbidity standards are made by diluting Primary Turbidity standards.
They are as accurate as the volumetric equipment and personnel used in the
dilution, as well as the Turbidity of the distilled water used in the dilution. These
standards are much lower in cost, and are suitable for most Turbidity
measurement requirements.