71
6.24
Turbidity Calibration
ALWAYS ensure that the temperature sensor is completely submerged during all
calibrations. Failure to submerge the sensor can result in false calibrations. And, ALWAYS
allow time for the temperature of the standard and the sensor to equilibrate.
YSI turbidity sensors are extremely sensitive and must use standards that
have been prepared according to details in
Standard Methods for the Treatment of
Water and Wastewater (Section 2130 B)
. These standards include:
• Formazin prepared according to
Standard Methods
• Dilutions of 4000 NTU formazin concentrate from Hach
• Hach StablCal ™ standards in various NTU denominations
• AMCO-AEPA standards prepared specifically for the YSI turbidity sensors supplied by YSI or a list of
approved vendors on www.ysi.com.
YSI recommends using a 2-point calibration. Using a 0 NTU standard and a second standard in the known turbidity
range of the water to be tested (e.g. 12.7 NTU for low turbidity or 126 NTU for high turbidity).
2-Point Optic Turbidity Calibration
Ensure that the sensor is activated and the sonde is reporting all necessary values under the ‘Sensor’ and ‘Report’
menus.
1. Rinse with water and pre-rinse with 0 NTU standard, then fill the cal cup with recommended amount of
0 NTU standard (typically deionized or distilled water with no suspended solids).
2. Open the ‘Calibrate’ menu.
3. Select ‘Optic T-Turbidity 6136.’
4. Select ‘2-Point.’
5. The screen will prompt you to enter the value of your standard. Always use the 0 NTU standard first. The
number in parentheses is the value of the last solution used to calibrate turbidity. Press ‘Enter’ to use this
value, or input the correct value and press ‘Enter.’
6. Observe the value of all measured conditions. Once the signal has stabilized for approximately 30 seconds,
press ‘Enter’ to accept the calibration.
7. Drain the standard from the cal cup and rinse with water.
8. The screen will prompt you to enter the value of your second standard. Use the NTU standard that will
be close to your measurement values. The number in parentheses is the value of the last solution used to
calibrate turbidity. Press ‘Enter’ to use this value, or input thecorrect value and press ‘Enter.’
9. Observe the signal value. Once it has stabilized for approximately 30 seconds, press ‘Enter’ to accept the
calibration.
10. Drain the standard from the cal cup and rinse with water.
NOTE
NOTE
6.2
6.2