© Hach Company, 2007. All rights reserved. Printed in Germany.
For technical assistance or ordering information: visit
www.hach.com
, call 800-227-4224 or email [email protected] Edition 1 December 2007
Quick Start Guide
For si792 P series 2-wire transmitters
DOC016.53.00794
7.
Calibrate the sensor. The two most common calibration methods are described below. Refer to
the user manual for other details. Refer to
Table 4
for default passcode settings.
Calibration with automatic buffer recognition
Complete the following steps to calibrate the pH probe:
a.
Press
CAL
, enter passcode: 1100,
ENTER
. The display will show CAL1.
b
Remove the pH and temperature probes from the process. Clean the probes and immerse
in the first buffer solution (any order). Briefly stir the solution with the probes.
c
Press
ENTER
. Automatic recognition of the buffer solution will begin. The display will first
show the hourglass and no buffer value, then the recognized buffer value followed by the
measured millivolt value. When the measurement is complete, the display will show CAL2.
d
When CAL2 is displayed, remove the probes from the first buffer solution and rinse thor-
oughly.
e
Complete a one-point calibration or start a two-point calibration:
•
One-point calibration
: press
CAL
to end the calibration. The slope (%) and offset (mV) of the
probe (based on 25 °C) will be displayed.
•
Two-point calibration
: immerse the probes in the second buffer solution. Press
ENTER
. The
buffer detection will repeat as for the first buffer solution. When complete, the slope (%) and off-
set (mV) of the probe (based on 25 °C) will be displayed.
f
Press
ENTER
,
ENTER
to return to the measurement mode. The HOLD mode will remain
active for 20 seconds.
g
Remove the probes from the buffer, rinse and return to the process.
Calibration by Comparison
The probe can be calibrated by entering the sample value from measurement in an instru-
ment such as a laboratory or portable meter (one-point calibration). The probe does not need
to be removed from the process during calibration. The sample temperature should corre-
spond to the measured process temperature for accurate results.
a.
Press
CAL
, enter passcode:
1105
,
ENTER
. The display will briefly show CAL PRD and
then StorE.
b
Collect a grab sample for measurement in the lab. Press
ENTER
to store the sample value
in the transmitter.
c
The cal mode indicator will flash to indicate that calibration is not complete. The transmit-
ter will continue to measure and display the current sample values.
d
Measure the grab sample with a laboratory or portable meter.
e
Press
CAL
, enter passcode:
1105
,
ENTER
to access the product calibration once more.
The display will briefly show CAL PRD and then CALC.
f
Edit the displayed value to match the value measured by the laboratory or portable meter
and press
ENTER
. The slope and offset will be shown.
g
Press
ENTER
to end the calibration. The display will show the measured value alternating
with Hold.
h
Press
ENTER
to return to the measuring mode. The outputs will remain in the hold mode
for approximately 20 seconds.
Note:
For comparison calibration via Foundation Fieldbus, see the pH user manual,
DOC026.53.00794. Comparison calibration via Profibus is not available.
Table 4 Default passcode settings
Display
Function
Default setting
Cal INFO
Calibration information
0000
CAL 0-CAL
Calibration zero
1001 (not for
si792x P-PA)
CAL CAL
Calibration
1100
CAL PROD
Product calibration
1105 (not for
si792x P-PA)
CAL RTD
Temperature probe adjustment
1015
CFG ERR
Error information
0000
CFG CONF
Configuration
1200
CFG SNSR MO Sensor monitor
2222
CFG OUT
Current source
5555
CFG SPCL ST
Administrator passcode. Use
ARROW
keys to
select NO or YES
1989
NO SPCL ST
Do not change
administrator passcode
Press
ENTER
to return to the default
passcode
Press
CONF
to exit the editor
YES SPCL ST
Change administrator
passcode
Press
ENTER
to accept the new
passcode
Press
CONF
to exit the editor
