The following sub-sections provide you with the initial
display screen that appears for each calibration rou-
tine. Use the
flow diagram for Turbidity calibration
at the end of Sec. 7 and the live screen prompts to
complete calibration.
7.10 Turbidity
7.10.1 Description
This section describes how to calibrate the turbidity sensor against a user-prepared standard as a 2-point calibra-
tion with di-ionized water, against a 20 NTU user-prepared standard as a single point calibration, and against a
grab sample using a reference turbidimeter.
THIS SECTION DESCRIBES HOW TO CALIBRATE THE MODEL 1056 WITH AN ATTACHED TURBIDITy
SENSOR AS PART OF THE COMPLETE CLARITy II TURBIDITy SySTEM. THE FOLLOWING CALIBRATION
ROUTINES ARE COVERED.
To calibrate Turbidity:
1. Press the
MENU
button
2. Select
Calibrate
. Press ENTER.
3. Select
Sensor 1
or
Sensor 2
corresponding to
Turbidity. Press ENTER.
4. Select
Turbidity.
Press ENTER.
The following screen will appear.
7.10.2 SLOPE CALIBRATION — Turbidity
This section describes how to conduct a 2-point cali-
bration of the turbidity sensor against a user-prepared
20NTU standard. The calibration requires two steps.
First, immerse the sensor in filtered water having very
low turbidity and measure the sensor output. Next,
increase the turbidity of the filtered water by a known
amount, typically 20 NTU, and measure the sensor
output again. The analyzer takes the two measure-
ments, applies a linearization correction (if necessary),
and calculates the sensitivity. Sensitivity is the sensor
output (in mV) divided by turbidity. A typical new sen-
sor has a sensitivity of about 10 mV/NTU. As the sen-
sor ages, the sensitivity decreases. The figure below
illustrates how turbidity calibration works. Before
beginning the calibration, the analyzer does a dark
current measurement. Dark current is the signal gener-
ated by the detector when no light is falling on it. The
analyzer subtracts the dark current from the raw scat-
tered light signal and converts the result to turbidity. In
highly filtered samples, which scatter little light, the
dark current can be a substantial amount of the signal
generated by the detector.
A detailed flow diagram is provided at the end of Sec. 7 to guide you through the calibration routines.
Measure Sec. Calibration function: default value Description
Turbidity 7.10.2 Slope Calibration
Slope cal with pure water and a standard of known turbidity
7.10.3 Standardize Calibration
Standardizing the sensor to a known turbidity
7.10.4 Grab Calibration
Standardizing the sensor to a known turbidity based on a
reference turbidimeter
S1: 1.234µS/cm 25.0ºC
S2: 12.34pH 25.0ºC
S
N
Calibrate?
Turbidity
S1: 1.234µS/cm 25.0ºC
S2: 12.34pH 25.0ºC
S
N
Calibrate
Slope
Standard
Grab
100
Table 7-12 Turbidity Calibration Routines
Instruction Manual
LIQ-MAN-1056
Section 7.0: Calibration
April 2017
Summary of Contents for Rosemount 1056
Page 4: ...Quick Start Guide Figure A Quick Start Guide ...
Page 5: ...Quick Reference Guide Figure B Model 1056 Menu Tree ...
Page 28: ...20 Instruction Manual LIQ MAN 1056 Section 2 0 Installation April 2017 ...
Page 50: ...42 Instruction Manual LIQ MAN 1056 Section 6 0 Programming the Measurements April 2017 ...
Page 84: ...76 Instruction Manual LIQ MAN 1056 Section 6 0 Programming the Measurements April 2017 ...
Page 122: ...114 Instruction Manual LIQ MAN 1056 Section 7 0 Calibration April 2017 ...
Page 124: ...116 Instruction Manual LIQ MAN 1056 Section 8 0 Return of Material April 2017 ...