KROHNE OPTISYS TUR 1050 EN - Manual (Page 31)

OPERATION
5
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OPTISYS TUR 1050
www.krohne.com 11/2012 - 4002444301 MA OPTISYS TUR 1050 R02 en
5.6.1 Calibration liquids
If you want to use the device over the entire measuring range (0.02...100 NTU/FNU or
0.02...1000 NTU/FNU), a complete calibration with three different calibration liquids is
necessary. If you require a device accuracy below 10 NTU/FNU (i.e. with potable water), you can
do the calibration with only two liquids (for this purpose the first calibration step can be
bypassed).
If you want to calibrate the device with formazin, always use a fresh stock suspension. The
reason is that diluted formazin is unstable and this can distort the calibration.
For EPA compliant calibration results the agency recommends that a calibration of online
devices takes place with primary calibration liquids at least every three months.
5.6.2 Calibration procedure (physical), inclusive indexing
To achieve the highest possible accuracy, the manufacturer recommends to index all calibration
cuvettes. Furthermore indexing a calibration cuvette accounts for normal scratches and
aberrations in the cuvette glass when performing a calibration. The manufacturer supplies all
his optionally available calibration cuvettes with indexing rings (see below).
Execute the following steps to make a physical calibration inclusive indexing the calibration
cuvettes:
• Press the button MODE/EXIT once to switch into the calibration mode.
i The arrow in the display appears beside "CAL", the lower display line shows alternating
"100" (turbidity value of the first calibration liquid in NTU/FNU) and ^, the upper line shows
the real-time reading.
INFORMATION!
Always note the following items to achieve the best calibration results:
• Use three calibration liquids with turbidities of 0.02, 10.0 and 100 or 1000 NTU/FNU if you
want to achieve the full-scale accuracy stated in this document.
• You can use formazin as a primary calibration liquid. Though the manufacturer recommends
the own calibration kit as a primary option because this liquids are more stable than formazin
and have a minimum shelf life of twelve months (the manufacturer's calibration kit is
purchasable as accessory part).
• Check the expiration dates of the liquids prior to calibration to ensure that they have not
expired.