18 19
• Once selected the second calibration point, set the HI
931001 (350 mV) or HI 8427 (350 or 1900 mV) simula-
tor to the same value and the calibration proceeds as for
the first point.
Note In ORP calibration there is no time-out.
Note Whenever a pH or ORP calibration is performed by means of
HI 504920, the HI 504920 date and time are automati-
cally set in HI 504910.
TEMPERATURE CALIBRATION
Check that the code 90 has been entered in Setup mode.
• Prepare a beaker containing crushed ice and water at 0°C
(32°F) and another one with hot water at 25°C (77°F) or
50°C (122°F).
• Use a Checktemp or another calibrated
thermometer with a resolution of 0.1° as a
reference thermometer.
• Immerse the temperature probe in the bea-
ker with ice and water as near to the
Checktemp as possible.
Note The instrument can support Pt100 or Pt1000 temperature
sensor and calibration can be performed with anyone of these
two probes.
• After entering the calibration mode, move through the menu
(using the æ or key) to choose the temperature and the
correct kind of used probe; the primary
LCD shows “°C” and the secondary LCD
gives indication about the kind of probe
(“100” indicates a Pt100 probe, while
“1000” stands for a Pt1000 probe).
Press the CFM key to confirm selection.
• The calibration has to be performed over two points: the
first point has to be 0°C and the second one can be cho-
sen between 25°C and 50°C.
Once confirmed the type of calibration,
the primary LCD will display the current
temperature measure and the second-
ary LCD will show the first calibration
point (0°C).
Note If (ALT+) SETUP are pressed instead of CFM, the calibration
value selection is aborted and the meter reverts back to a
two-point calibration.
Note Whenever a pH or ORP calibration is performed by means of
HI 504920, the HI 504920 date and time are automati-
cally set in HI 504910.
ORP CALIBRATION
Check that the code 90 has been entered in Setup mode.
To perform ORP calibration it is necessary to connect an HI
931001 or HI 8427 simulator to the BNC socket.
The meter has to be set as ORP controller.
• A two-point calibration has to be performed: the first point
value is 0 mV and the second one can be chosen between
350 mV and 1900 mV.
• Enter the calibration mode, select the ORP calibration (use
the æ and keys to move through setup menu) and press
the CFM key.
• Set the HI 931001 or HI 8427 simulator to 0 mV.
• The primary LCD will display the cur-
rent mV measure and the secondary
LCD will show the first calibration
point (0 mV).
• When the reading becomes stable,
if the ORP value is close to the calibration point, the “CFM”
indicator starts blinking; otherwise the “WRONG” indica-
tor blinks and the “CAL” is fixed on.
• In the first case press CFM to confirm calibration. The
meter will proceed showing the scrolling message “Press
CFM again to confirm the current buffer or right to es-
cape” (to prevent from confirming the calibration point
inadvertently). Pressing again CFM the secondary LCD will
display the second calibration point.
• In the second case (blinking “WRONG”) the meter will re-
main in the WRONG state until the reading becomes unstable
or the calibration mode is exited by pressing the CAL key.
• For the second calibration point it is possible to choose
between 350 mV and 1900 mV. Pressing the æ or key
the value on the secondary LCD will switch between the two
possibilities.
