Hanna Instruments HI 254 User manual

1
Instruction Manual
HI 254
Microprocessor-Based
pH/mV/ºC
Bench Meter
www.hannainst.com

2
TABLE OF CONTENTS
WARRANTY.........................................................................................................................2
PRELIMINARYEXAMINATION..............................................................................................3
GENERALDESCRIPTION..................................................................................................... 3
FUNCTIONALDESCRIPTION................................................................................................4
HI254SPECIFICATIONS.................................................................................................... 5
OPERATIONALGUIDE.........................................................................................................6
pHCALIBRATION................................................................................................................9
GOODLABORATORYPRACTICE(GLP)...................................................................................12
LOGGINGFUNCTION..............................................................................................................14
SETUP.....................................................................................................................................17
TEMPERATURE CALIBRATION (for technical personnel only) ........................................... 21
mV CALIBRATION (for technical personnel only) .............................................................. 23
RELATIVEmVCALIBRATION..............................................................................................24
PCINTERFACE....................................................................................................................25
pH VALUES AT DIFFERENT TEMPERATURES .................................................................... 27
ELECTRODECONDITIONING& MAINTENANCE .................................................................. 28
TROUBLESHOOTINGGUIDE...............................................................................................31
TEMPERATURE CORRELATION FOR pH SENSITIVE GLASS ............................................... 32
ACCESSORIES......................................................................................................................33
WARRANTY
HI 254 is guaranteed for two years against defects in workmanship and
materials when used for its intended purpose and maintained according to
instructions. Electrodes and probes are guaranteed for six months. This
warranty is limited to repair or replacement free of charge.
Damage due to accidents, misuse, tampering or lack of prescribed maintenance
is not covered.
If service is required, contact the dealer from whom you purchased the
instrument. If under warranty, report the model number, date of purchase,
serial number and the nature of the problem. If the repair is not covered by
the warranty, you will be notified of the charges incurred. If the instrument is
to be returned to Hanna Instruments, first obtain a Returned Goods Authori-
zation number from the Technical Service department and then send it with
shipping costs prepaid. When shipping any instrument, make sure it is
properly packed for complete protection.
Dear Customer,
Thank you for choosing a Hanna Instruments product.
Please read this instruction manual carefully before using the instrument.
This manual will provide you with the necessary information for correct use of
the instrument, as well as a precise idea of its versatility.
If you need additional technical information, do not hesitate to e-mail us at
[email protected] or turn to the back cover for our worldwide contact list.
This instrument is in compliance with directives.

3
PRELIMINARY EXAMINATION
Remove the instrument from the packing material and examine it carefully to
make sure that no damage has occurred during shipping. If there is any
damage, notify your Dealer or the nearest Hanna Customer Service Center.
Each instrument is supplied with:
 HI 1131B Glass-body Combination pH Electrode with 1 m (3.3') Cable
 HI 7669/2W Temperature Probe
 HI 76404 Electrode Holder
 pH 4.01 & 7.01 Buffer Solutions (20 mL each)
 HI 7071S Electrolyte Solution
 12VDC Power Adapter
 Instruction Manual
Note: Save all packing material until you are sure that the instrument
functions correctly. All defective items must be returned in the original
packing with the supplied accessories.
The HANNA HI 254 is a logging microprocessor-based pH and temperature
bench meter.
HI 254 can also measure Oxidation Reduction Potential (ORP) in mV range.
Relative mV feature is also provided.
pH measurements are compensated for temperature effect manually or
automatically with the HI 7669/2W temperature probe.
Up to five-point calibration is possible, using seven memorized buffers (1.68,
4.01, 6.86, 7.01, 9.18, 10.01 and 12.45 pH).
The GLP feature provides a guarantee of data consistency.
An alarm time-out is available to alert the user that too much time elapsed
since the last pH calibration.
The instrument can store data in memory at the users request for later
retrieval.
Hanna Instruments reserves the right to modify the design, construction
and appearance of its products without advance notice.
GENERAL DESCRIPTION

4
1) Liquid Crystal Display (LCD).
2) CFM/GLP key, to confirm different values or to display Good Laboratory
Practice information.
3) CAL key, to enter and exit/escape calibration mode.
4) /ºC key, to manually decrease temperature value or other parameters.
5) /ºC key, to manually increase temperature value or other parameters.
6) RCL key, to enter/exit recall mode.
7) LOG key, to store measured data.
8) SET/CLR key, to enter/exit setup mode, clear pH calibration or delete
logged data.
9) RANGE key, to select measurement range or to switch focused data.
10) ON/OFF switch.
11) Power supply socket.
12) BNC electrode connector.
13) Electrode reference socket.
14) Temperature probe socket.
15) RS232 serial communication connector.
FUNCTIONAL DESCRIPTION
Front Panel
Primary LCD
Secondary LCD
1
9
3
2
7
4
6
5
10
8
POWER
12VDC
INPUT
REF
TEMP
11 12 13 14
Rear Panel
C
CAL
CFM
READY
BUF
WRONG
LOG mV pH TIME% DATE INTV
BUFFER pH
RS232
15
Functions pH Calibration - 5 points
RCL LOG
CLR
SET
CC
RANGE
GLP
CFM
CAL
CFM
/
CAL
RANGE
GLP
LOG
SET/CLR
RCL
pH / ORP Meter
HI 254
Confirm Calibration
in selected pH Buffer
Select pH Buffer
Start/Exit Calibration
Select pH/ORP/ mV
Scroll Log Data Rel
Show GLP Data
Store Log Data
Set Instrument Parameters
Clear Calibration/Log Data
Recall Log Data

5
HI 254
SPECIFICATIONS
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6
OPERATIONAL GUIDE
POWER CONNECTION
Plug the 12 VDC adapter into the power supply socket.
Note: This instrument uses non volatile memory to retain the pH, mV,
temperature calibrations and all other settings, even when unplugged.
Note: Make sure a fuse protects the main line.
ELECTRODE AND PROBE CONNECTIONS
For pH or ORP measurements connect an electrode with internal reference to
the BNC connector on the back of the instrument.
For electrodes with a separate reference connect the electrodes BNC to the BNC
connector and the reference electrode plug to the reference socket.
For temperature measurements and automatic temperature compensation
connect the temperature probe to the appropriate socket.
INSTRUMENT START-UP
Turn the instrument on by pressing the ON/OFF switch.
All LCD tags are displayed and a beep is sounded while
the instrument performs a self test.
pH MEASUREMENTS
Make sure the instrument hasbeen calibrated before taking
pH measurements.
Submerge the electrode tip and the temperature probe
approximately 4 cm (1½) into the sample to be tested
and stir gently. Allow time for the electrode to stabilize.
The pH is displayed on the primary LCD and the temperature on the
secondary LCD.
If the reading is out of range, the closest full-scale value will be displayed
blinking on the primary LCD.
pH
C
pH
C
C
CAL
CFM
READY
BUF
WRONG
LOG mV pH TIME% DATE INTV
BUFFER pH

7
If measurements are taken successively in different samples, it is recommended
to rinse the electrode thoroughly with deionized water or tap water and then
with some of the next sample to prevent cross-contamination.
The pH reading is affected by temperature. In order to measure the pH
accurately, the temperature effect must be compensated for. To use the
Automatic Temperature Compensation feature, connect and submerge the
HI 7669/2W temperature probe into the sample as close as possible to the
electrode and wait for a few seconds.
If the temperature of the sample is known, simple manual compensation can
be performed by disconnecting the temperature probe.
The display will then show the default temperature of 25 ºC
or the last temperature reading with theºC tag blinking.
The temperature can now be adjusted with the ARROW keys
(from 9.9 ºC to 120.0 ºC).
mV/ORP MEASUREMENTS
An optional ORP electrode must be used to perform ORP measurements
(see Accessories).
Oxidation-Reduction Potential (REDOX) measurements provide the quantification
of the oxidizing or reducing power of the tested sample.
To correctly perform a REDOX measurement, the surface of
the ORP electrode must be clean and smooth.
Press RANGE to enter mV range.
Submerge the tip of the ORP electrode 4 cm (1½) into
the sample to be tested and allow a few seconds for the
reading to stabilize.
The instrument displays the mV reading on the primary LCD and the
temperature on the secondary LCD.
If the reading is out of range, the closest full-scale value will be displayed
blinking on the primary LCD.
C
C C
mV
C
mV
C

8
RELATIVE mV MEASUREMENTS
Press RANGE until rEL message will be displayed on the secondary LCD line
for about one second and mV tag will blink. After one second the
temperature will be displayed on the secondary LCD.
The reading displayed by the instrument is equal to the difference between
the current mV input value and relative mV offset established in the relative
mV calibration.
TEMPERATURE MEASUREMENTS
Connect the HI 7669/2W temperature probe to the appropriate
socket and turn the instrument on.
Immerse the temperature probe into the sample and allow
the reading on the secondary LCD to stabilize.
mV
C

9
pH CALIBRATION
Calibrate the instrument frequently, especially if high accuracy is required.
The instrument should be recalibrated :
Whenever the pH electrode is replaced.
At least once a week.
After testing aggressive chemicals.
If CAL INTV tags are blinking during measurement.
Every time you calibrate the instrument use fresh buffers and perform an
electrode Cleaning Procedure (see page 30).
PREPARATION
Pour small quantities of the buffer solutions into clean beakers. If possible, use
plastic or glass beakers to minimize any EMC interferences.
For accurate calibration and to minimize cross-contamination, use two beakers
for each buffer solution. One for rinsing the electrode and one for calibration.
If you are measuring in the acidic range, use pH 7.01 or 6.86 as first buffer and
pH 4.01 or pH 1.68 as second buffer. If you are measuring in the alkaline range,
use pH 7.01 or 6.86 as first buffer and pH 10.01 or pH 12.45 as second buffer.
PROCEDURE
Calibration has a choice of 7 memorized buffers: pH 1.68, 4.01, 6.86, 7.01,
9.18, 10.01 and 12.45.
It is recommended to perform at least a two-point calibration. However, the
instrument allows up to five-point calibration, as described on page 11.
ONE-POINT CALIBRATION
Immerse the pH electrode and the temperature probe
approximately 4 cm (1½) into a buffer solution of
your choice (pH 1.68, 4.01, 6.86, 7.01, 9.18, 10.01
or 12.45) and stir gently. The temperature probe
should be close to the pH electrode.
Press CAL. The CAL and 
BUF
 tags will appear
and the 7.01 buffer will be displayed on the
secondary LCD.
If necessary, press the ARROW keys to select a different buffer value.
CAL
BUFFER pH
BUF
pH

10
The   tag will blink on the LCD until the reading is
stable.
When the reading is stable and close to the selected buffer, the
READY tag will be displayed and the CFM tag will blink.
Press CFM to confirm calibration.
The calibrated value will be displayed on the primary LCD
and the second expected buffer value on the secondary
LCD.
Press CAL to quit calibration. The instrument will return
to measurement mode and will memorize the one-point
calibration data.
TWO-POINT CALIBRATION
Any two of the 7 memorized buffers can be used for this purpose. However, it
is recommended that pH 6.86 or 7.01 to be chosen as first calibration point
and pH 4.01 (acidic) or pH 9.18/10.01 (alkaline) as second calibration point.
Proceed as described in One-point calibration section, but do not quit
calibration by pressing CAL at the end.
After the first calibration point is confirmed, immerse the pH electrode and
the temperature probe approximately 4 cm (1½) into the second buffer
solution and stir gently. The temperature probe should be close to the pH
electrode.
If necessary, press the ARROW keys to select a different buffer value.
The   tag will blink on the LCD until the reading is
stable.
When the reading is stable and close to the selected buffer, the
READY tag will be displayed and the CFM tag will blink.
Press CFM to confirm calibration.
Press CAL to quit calibration. The instrument will return
to measurement mode and will memorize the one-point
calibration data.
THREE TO FIVE-POINT CALIBRATION
Any of the unused buffers in previous calibration can be used for this purpose.
Proceed as described in Two-point calibration section,but do not quit
calibration by pressing CAL at the end.
After the second calibration point is confirmed, immerse the pH electrode
and the temperature probe approximately 4 cm (1½) into the next
buffer solution and stir gently. The temperature probe should be close to
the pH electrode.
CAL
BUF
pH
BUFFER pH