740 Portable Suspended Solids
10 Profile Calibration
10.1 Calibration – General
Calibration of the 740 Monitor is very important, errors in the calibration process will
effect the measurement performance of the instrument. The following section describes
the various aspects of calibrating the 740 Monitor and has been written with the
understanding that the user has knowledge of the measurement being made.
Any containers used to store calibration samples should be cleaned prior to use. This is
particularly important when performing the zero point calibration on a low range
application.
The most accurate method of calibration is using a primary standard, i.e. calibration in
the actual solution against a laboratory result. Where this is not possible or where the
trend of the reading is necessary rather than an absolute value it is acceptable to use a
secondary standard.
Note: Each profile must be separately calibrated, ensure that the required profile
has been selected prior to calibration.
10.2 Methods of Calibration
10.2.1 Primary Standard
This method of calibration will give the best results however it does require the use of a
laboratory to carry out a gravimetric analysis of the calibration solution. The result of
the gravimetric analysis is used as the calibration value.
10.2.2 Secondary Standard
In cases where it is not possible to carry out calibration using a primary standard,
secondary standards such as Fullers Earth or Formazin can be used. It is important to
remember however that instruments calibrated in this way will give results based on the
secondary standard used and this will differ from the results of a gravimetric analysis.
A guide to the preparation of Fullers Earth and Formazin solutions is located at the
back of this manual.
172430IM-Iss07.odt 172430IM-Iss07 Issue Date 23/10/2014 Page 25 of 46
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