Hanna Instruments HI 21 Series - Manual (Page 22)

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mV INPUT CALIBRATION
The pH/mV controller is factory calibrated for the mV and
temperature inputs. However, the user may also perform a
mV calibration.
• Short the Connection for Potential Matching Pin (#5 on
page 7) and the Connection for the Electrode Reference
(#6 on page 7) with a jumper wire.
• Attach a HI 931001 (HI 21) or HI 8427 (HI 22) simulator
to the BNC socket.
• Press and hold first CFM and then
CAL to enter the mV Input Cali-
bration mode.
• Execute the password procedure.
• With HI 21, the meter will ask for the calibration proce-
dure code number. The following table lists the possible
values of the input code and calibration points:
INPUT CODE POINTS CAL.VALUES INPUT RANGE
mV 0 2 0 & 350 or 0 & 1900* ±2000,
Temp. 1 2 0 & 25 or 0 & 50 -9.9 to 120.0 ° C
* One of the points must be 0. 1900 mV calibration point is available
on HI 22 models only.
When calibrating the mV of HI 22 models, enter the cali-
bration mode by pressing CAL and confirming the password
(as for pH calibration of HI 21). No code selection is re-
quired.
• Use or to select code 0 for mV calibration and press
CFM to enter.
• CAL will blink on the LCD until the
meter confirms a steady reading.
OFFSET AND SLOPE DIRECT SELECTION (HI 21523 ONLY)
Whenever the pH electrode offset and slope parameters are
known, it is possible to directly calibrate the meter entering
the electrode parameters.
• Press the “CAL DATA” and then “SETUP”. The LCD will
show the default offset of -5.0 mV.
• Using the , and enter the electrode offset param-
eter (the value must be between -100 and +100 mV).
• Confirm the value by pressing CFM.
If offset is invalid the “WRONG”
indicator will blink on the LCD.
• The LCD will then show the default
slope for Hanna electrodes: 57.5
mV/pH.
Note If CAL DATA or LCD are pressed before CFM, calibration is
aborted without changing the data of previous calibration.
• Using the , and enter the electrode slope param-
eter (the value must be between +40 and +80 mV/pH).
• Confirm the value by pressing CFM. If
slope is invalid the “WRONG” indi-
cator will blink on the LCD.
Note Press LCD or CAL DATA to exit cali-
bration. The slope will be set to the
default value (57.5 mV/pH).
Note Calibration data can be viewed pressing CAL DATA while in
normal mode but no pH buffer values will be displayed dur-
ing the data scrolling on LCD.