idronaut Ocean Seven 304Plus Operator's Manual page 73

APPENDIX D – SEAPOINT TURBIDITY METER
TURBIDITY METER
Meas. scale 1, F.S.[>750 FTU] y=a+bx
(a)=0.000000
(b)=0.000000
and continues with the next scale
Meas. scale 2, F.S.[ 500 FTU] y=a+bx
(a)=0.000000
(b)=0.000000
and continues with the next scale
Meas. scale 3, F.S.[ 125 FTU] y=a+bx
(a)=0.000000
(b)=0.000000
and continues with the next scale
Meas. scale 4, F.S.[ 25 FTU] y=a+bx
(a)=0.000000
(b)=0.000000
D.3.1 Calibration solution preparation
Calibration of a turbidity instrument by using Formazin or another primary standard is usually done
in the laboratory. Turbidity standards for various ranges are available commercially, for instance
Formazin based standards can be diluted by using a dilution formula to create a set of calibration
standards of different concentrations. A technique for the preparation of such turbidity standards is
discussed by Wilde and Gibs 1998 (see note 1).
Thus, preparation of the calibration standards is a customer's responsibility. From a technical point of
view, we suggest that at least a blank and two calibration standard solutions should be prepared for
each measuring range: 25,125,500 and greater than 750 FTU. Furthermore, we suggest that the
calibration solutions should be equally spaced through the Turbidity Meter measuring scales (i.e. 0.0,
60.0, 120 for the 125 scale).
Before immersing the Turbidity Meter sensor in a standard solution, the sensor must be cleaned,
rinsed at least three times with turbidity-free water, and carefully dried. Turbidity-free water is
prepared as described by Wilde and Gibs (1998).
Note
Wilde, R.F., and Gibs, Jacob, 1998, Turbidity, in Wilde, F.D., and Radtke, D.B., eds., 1998, Field measurements,
in National field manual for the collection of water-quality data: U.S. Geological Survey Techniques of Water-
Resources Investigations, book 9, chap. A6.7, 30 p.
IDRONAUT – Brugherio (MB) OCEAN SEVEN 304Plus CTD
65
12-2015