9
8860 Dual Channel Conductivity/Resistivity Controller
Calibration Procedure
The 8860 has been electronically calibrated at the factory.
• Procedure
A
veri
fi
es the accuracy and linearity of the 8860 by simulating temperature and conductivity values with precision (±0.1%)
fi
xed resistors.
• Procedure B is a wet calibration. This procedure uses the sensor input and NIST traceable test solutions.
A) Accuracy Veri
fi
cation with Precision Resistors (Electronic Calibration):
1. Simulate the Temperature
The temperature input to the 8860 is a PT-1000 thermistor, where 1000 Ohms (
Ω
) is equal to 0ºC and a change of 3.84
Ω
equals a
1ºC change. (1000
Ω
= 0ºC, 1003.84
Ω
= 1.0ºC, 1007.68
Ω
= 2.0ºC...................1096
Ω
= 25ºC)
• Connect a resistor (1000
Ω
to 1096
Ω
) between "Temp" and "Iso. Gnd" terminals.
• Set Temp;
Adjust the temperature to exact value based on the measured resistance. (See Editing Procedure, Calibrate menu).
• To verify the 8860 temperature linearity, connect a second resistor value to the terminals.
• If the 8860 does not display the correct value, service is required. ( ± 0.5ºC)
2. Simulate the Conductivity
You may calculate the exact Resistance needed to simulate a speci
fi
c conductivity value , or you may calculate the exact Conductivity
based on a resistor value:
Resistance
= Cell constant
e.g.
0.1 Cell
= 5,000
Ω
or 5 K
Ω
conductivity
(Siemens*)
0.000020
(Siemens*)
Conductivity
=
Sensor cell
e.g.
0.1 Cell
= 0.000001 Siemens*
Simulation resistance (
Ω
)
100,000 (
Ω
)
or 1
μ
S/cm
(*1
μ
S = 1 X 10
-6
Siemens or 0.000001 Siemens)
• Connect the conductivity resistor between the "Sgnl 1 " and "Iso Gnd" (or Sgnl 2 and Iso Gnd) terminals.
• Set Cond: Adjust the conductivity value based on the resistor value. (See Editing Procedure and Calibrate menu).
• Verify the linearity of the 8860 by connecting a second Conductivity resistor of a different value.
• If the 8860 does not display the correct value (± 2% of reading), service is required.
B) Wet Calibration with NIST Traceable Solutions:
When using NIST traceable standards, review the temperature information provided with the test solution. Prevent contamination of the
test solution. The sensor must be at the temperature speci
fi
ed on the test solution label.
• Remove the sensor from the system. Rinse the sensor in a small amount of test solution.
• Place the sensor into the test solution.
• Place a reference thermometer into the same solution.
• Allow
suf
fi
cient time for the temperature to stabilize.
• Set Temp:
Adjust the temperature value based on the reference thermometer. (See Editing Procedure.)
• Set Cond:
Adjust the conductivity value based on the test solution value. (See Editing Procedure.)
• Verify the linearity of the 8860 by placing the sensor into a second test solution of a different value.
• If the 8860 does not display the correct value (Temperature ± 0.5ºC, Conductivity ± 2% of reading), service is required.
