Adjust The T-Factor For Non-Standard Cable Lengths; Calibrate The Sensor; Zero Calibration Procedure - Hach 3400 Serie Manual Del Usuario

Option Description
LOG SETUP Sets the time interval for data storage in the data log—
5, 30 seconds, 1, 2, 5, 10, 15 (default), 30, 60 minutes.
RESET DEFAULTS Sets the configuration menu to the default settings. All
sensor information is lost.

Adjust the T-factor for non-standard cable lengths

When the sensor cable is extended or shortened from the standard 6 m
(20 ft), the resistance of the cable changes. This change reduces the
accuracy of temperature measurements. To correct for this difference,
calculate a new T-factor.
Note: This procedure applies only to sensors with a PT1000 temperature element.
Sensors with a PT100 temperature element are less accurate.
1. Measure the temperature of a solution with the sensor and with an
independent, reliable instrument such as a thermometer.
2. Record the difference between the temperature measured from the
sensor and from the independent source (actual).
For example, if the actual temperature is 50 °C and the sensor reading
is 53 °C, the difference is 3 °C.
3. Multiply this difference by 3.85 to get an adjustment value.
Example: 3 x 3.85 = 11.55.
4. Calculate a new T-factor:
• Sensor temperature > actual—add the adjustment value to the T-
factor on the sensor cable
• Sensor temperature < actual—subtract the adjustment value from
the T-factor on the sensor cable
5. Enter the new T-factor in the Configure, Temp Element menu.

Calibrate the sensor

About sensor calibration
Two methods can be used to calibrate the conductivity sensor:
• Dry cal—enter the unique cell constant K and T-factor from the sensor
label in the Configure menu to define the calibration curve.
• Wet cal—use air (Zero Cal) and a reference solution or process sample
to define a calibration curve. A reference solution calibration is
recommended for best accuracy. When the process sample is used, the
reference value must be determined with a secondary verification
instrument. Be sure to enter the T-factor in the Configure menu for
accurate temperature compensation.
During calibration, data is not sent to the datalog. Thus, the datalog can
have areas where the data is intermittent.

Zero calibration procedure

Use the zero calibration procedure to define the unique zero point of the
conductivity sensor. The zero point must be defined before the sensor is
calibrated for the first time with a reference solution or process sample.
1. Remove the sensor from the process. Wipe the sensor with a clean
towel to make sure the sensor is dry.
2. Push the MENU key and select Sensor Setup, [Select Sensor],
Calibrate.
3. Push ENTER to select Zero Cal.
4. If the passcode is enabled in the security menu for the controller, enter
the passcode.
5. Select the option for the output signal during calibration:
Option Description
Active The instrument sends the current measured output value during the
calibration procedure.
Hold The sensor output value is held at the current measured value
during the calibration procedure.
Transfer A preset output value is sent during calibration. Refer to the
controller user manual to change the preset value.
6. Hold the dry sensor in the air and push ENTER.
7. Review the calibration result:
• Pass—the zero point is set.
• Fail—the value is outside of accepted limits. Make sure the sensor
is dry and repeat the zero calibration procedure.
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