Hanna Instruments HI 504920, Instruction Manual, Page: 7 / 15

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HI 504910 pH READING CHECK
The check of the HI 504910 pH reading against the HI 504920 pH
reading is possible at any time.
Perform the following steps:
• Connect the infrared optical interface cable to
HI 504910 .
• Press (ALT+) TXCAL.
• The primary LCD shows the HI 504910
pH reading and the secondary one dis-
plays the
HI 504920 pH reading. Both
pH tags blink alternatively.
• Press (ALT+) TXCAL to return to normal mode.
Note: In case of a communication error
between
HI 504920 and HI 504910 ,
the LCD shows the "rSEr" message.
Check interface cable and connections.
Note: If the LCD shows "...", verify that HI 504910 is configured to
measure pH and not ORP.
Note: At point 5, if the probe offset is
outside the allowed limits, if
HI
504910 is configured to measure ORP,
or if some other error occurs, the LCD
shows a blinking "bAd" message. To cancel this message and
return to normal mode, press TXCAL. Then restart the calibra-
tion procedure from the beginning.
Note: Although it is recommended to perform the entire calibration
procedure with the infrared optical interface cable connected
between
HI 504920 and HI 504910 (step 1), it can happen
that the HI 504910 must be located in a place difficult to
reach when the HI 504920 pH probe is immersed in the
solution.
In this case, step 1 can be skipped. After step 4 the primary
LCD will show the blinking "CALt" message and the secondary
one a countdown starting from 120 seconds.
In this situation, the pH probe can be taken out of the
solution and the interface cable must be connected to the
HI
504910 before the countdown reaches zero.
Calibration will then continue from step 5. At step 6 the pH
tag of the secondary LCD does not blink, because the corre-
sponding pH reading is the one taken with the
HI 504920 pH
probe immersed when TXCAL was pressed.
If the interface cable is not connected before the end of the
countdown, the LCD shows
the "tiMEout" message and
the calibration procedure is
aborted.
Note: To perform a two-point calibration procedure with standard pH
buffers (pH 4.01, 6.86, 7.01, 9.18, 10.01) through the
HI
504910 terminal mode, see the "Setup mode section", code
90.
Note: A probe life verification (as described in the "GLP" section) is
performed on the
HI 504910 pH probe; the message "old
probe" or "dead probe" could appear at the end of calibration.