Hach GS1140 Manual Del Usuario página 16

4.2 Calibration
The sensor must be calibrated before initial use. Then, calibrate the sensor again at 1-month
intervals for the best accuracy. Refer to the calibration instructions supplied with the calibration kit,
which is sold by CertGas (https://certgas.com).
Before calibration, make sure that the statements that follow are true:
• The measurement location is within the operating temperature range of the sensor. Refer to
Table 1 on page 3.
• The sensor is clean. Refer to
• The Power/4-20 mA sensor cable supplies power to the sensor.
• The RS-232 sensor cable is attached to the sensor, if applicable.
Note: The sensor may be calibrated less frequently (at 2- to 3-month intervals). However, more frequent
calibrations increase the accuracy of the sensor.
Note: More frequent calibration may be necessary for sensors submerged in high-fouling locations (e.g., post-
dosing).
4.3 Change the measurement units of the 4–20 mA output
The status LED on the sensor shows the measurement units currently represented by the 4–20 mA
analog output. Refer to
When only the Power/4-20 mA sensor cable is used (no RS-232 sensor cable) for communication,
change the measurement units represented by the 4–20 mA analog output so they are correct for the
type of measurement: mg/L (liquid measurements) or ppm (air measurements).
To change the measurement units, do the steps that follow:
Note: This procedure does not change the RS-232 signal from the sensor.
1. Remove the unwanted material that has collected on the sensor. Refer to
sensor on page 20.
2. Disconnect the cables from the sensor.
3. Install the calibration cap on the sensor. Refer to the instructions supplied with the calibration cap
and flow regulator for the correct installation.
4. Connect the Power/4-20 mA cable to the sensor. Make sure that the Power/4-20 mA sensor
cable supplies power to the sensor.
5. When the Status LED on the sensor flashes red and green, remove the calibration cap from the
sensor.
The status LED flashes green again to show the new measurement units.
Color
Green, one flash
Green, two flashes
4.4 Mechanical installation
4.4.1 Installation options
Figure 10 and Figure 11
Note: Do not attach the sensor to a wall, because rags and unwanted material will collect on the sensor.
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Examine and clean the sensor
Table 7.
Table 7 Status LED
Measurement units
0–5 mg/L, liquid measurements
0–1000 ppm, air measurements
show the different sensor installation options.
on page 20.
Examine and clean the