8
2850 Conductivity/Resistivity Sensor Electronics
EasyCal is a single-point calibration system.
During this procedure, if the measured value is within ±10% of any of the test
values listed below, the 2850 will automatically recognize the test value and calibrate the output to that value.
NOTE:
The
fi
rst step (Reset) is recommended each time an electrode is replaced, but is NOT necessary upon initial installation or
periodic calibration.
1. Reset
the 2850 Sensor to factory calibration: Set all switches on SW3 (and SW4 for Dual Input) to OPEN. Apply power, wait
at least 3 seconds, then press and hold SW1 until the LED (D3) comes on steady then goes off again (approx. 10 seconds).
When the LED goes off, release SW1; reset is complete. Reset SW3 and SW4 to the proper settings.
2. Place
the electrode/sensor assembly into the conductivity test solution appropriate to your operating range. Shake the
electrode to dislodge any air bubbles visible on the surface of the electrode.
• 146.93
μ
S, 1408.8
μ
S, 12856
μ
S (per ASTM D1125-95)
• 10
μ
S, 100
μ
S, 200
μ
S, 500
μ
S, 1000
μ
S, 5000
μ
S, 10,000
μ
S, 50,000
μ
S, 100,000
μ
S.
Allow at least 2 minutes for the electrode response to stabilize.
3. Press
and hold SW1 for approximately 8 to 10 seconds. During this time, the LED will come on steady then go back off.
(If the LED blinks several times rapidly, the calibration was not successful. See the troubleshooting section).
Calibration is complete. Return the system to service.
EasyCal
Dual Input Calibration
Dual Input 3-2850-63 Electronics
• The 2850-63 can only be calibrated if both inputs are used, or if Input 2 is disabled.
• To disable Input 2: Set SW4, #4 to OPEN.
• Place each sensor into a test solution that represents the operating range of that sensor. When SW1 is pressed, the 2850 will
calibrate both inputs simultaneously.
• Dual Input applications usually include one sensor with a smaller cell constant and one sensor with a larger cell constant.
Place the larger cell constant on Input 1
. This allows periodic recalibration of the larger cell by simply turning Input 2 OFF (OPEN).
Calibration
• All 2850 Conductivity/Resistivity Sensor Electronics are factory calibrated for maximum out-of-the-box accuracy.
• The EasyCal feature allows calibration to be performed at the sensor.
a. SW2: 4 to 20 mA output range selection switch bank
b. Power and Output terminal block: 4 to 20 mA or
Digital (S
3
L) Outputs
c. SW3 and SW4: Electrode Cell Constant selection
switch banks
d. D3: LED indicator
e. SW1: EasyCal Push-button
f.
Input 1 & Input 2: Conductivity Electrode connections
SW1
SW2
SW3
SW4
D3
1
2
3
1
2
3
4
ON
CTS
1
2
3
4
ON
CTS
1
2
3
4
ON
CTS
Input 1
Input 2
e
d
b
a
c
f
The 2839-2842 Conductivity sensors come with a certi
fi
cate
of calibration. This certi
fi
cate provides information regarding
the actual cell constant and temperature offset as tested and
veri
fi
ed according to NIST standards. This information has
been programmed into the 2850 electronics as its default
factory value. If required, the sensor can be recerti
fi
ed by
contacting the GF Signet repair department.
NOTE:
When the electrode is changed from its original factory
provided electrode or the application requires a cell constant
change, reset SW3 or SW4 switches (see page 6).
Then perform a wet calibration with calibration standards.
