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

11
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.
If the fifth calibration point is reached, the instrument
stores the calibration value and returns to normal mea-
surement mode, or else it goes to the next calibration point.
Note: If the value measured by the instrument is not close to the
selected buffer, WRONG 
BUF
 and WRONG   tags will
blink alternately. In this case, check if the correct buffer has been
used or regenerate the electrode by following the Cleaning Proce-
dure (see page 30). If necessary, change the buffer or the
electrode.
If WRONG, Buffer pH tags and Old tag on the secondary LCD
are displayed blinking, an inconsistency between new and previous
(old) calibration is detected. Clear calibration parameters by
pressing SET/CLR and proceed with calibration from the current
calibration point (the instrument will keep all confirmed values
during current calibration).
The WRONG tag and temperature value are displayed blinking
if temperature reading is out of the defined temperature range of
the buffer. Calibration cannot be confirmed in this situation.
Press RANGE to toggle between pH buffer, buffer
number and temperature reading on the secondary
LCD during calibration.
Note: Calibration parameters are evaluated taking in consideration the new
values for the confirmed buffers in current calibration and the old
values, if existing, for the other buffers. To clear old calibration values,
press SET/CLR before exiting calibration.

12
GOOD LABORATORY PRACTICE (GLP)
GLP is a set of functions that allows storage and retrieval of data regarding the
maintenance and status of the electrode.
All data regarding the last calibration (one, two, three, four or five-point) is
stored for the user to review when necessary. This data includes the following:
calibration time stamp, offset (mV), average of slope (%), calibration buffers
and the time until a new calibration is required.
CALIBRATION ALARM TIME-OUT
HI 254 allows the user to set the number of days before the next required
calibration. This value can be set from 1 to 7 days. The default setting is OFF
(disabled).
The instrument checks if the time-out time has expired. If the time elapsed, the
CAL INTV tags will blink as a reminder.
Note: If the instrument was not calibrated, the CAL INTV tags will be
displayed even if the feature is disabled in SETUP menu.
LAST CALIBRATION DATA
Last calibration data is stored automatically after a successful calibration.
To view the pH calibration data, press GLP while in measurement mode.
The instrument will display the time (hh:mm) of the last calibration.
Press the ARROW keys to view the next logged calibration parameter
(pressing the ºC key):
The date (yyyy.mm.dd).
The pH calibration offset.
The pH calibration slope (the GLP slope is the average of the calibration
slopes; the percentage is referred to the ideal value of 59.16 mV/pH).
TIME
CAL
DATE
CAL
CAL mV
%
CAL

13
The pH calibration buffers in calibrating order.
The first pH calibration buffer:
The second pH calibration buffer:
The third pH calibration buffer:
The fourth pH calibration buffer:
The fifth pH calibration buffer:
Note: The OLd message displayed beside the pH value means that
this buffer was not used during last calibration. Press and hold
down SET/CLR if you want to see calibration date (or time if old
calibration was made in the same day with current calibration).
If no bUF message appears on the LCD, the instrument informs
you that calibration was performed in less than five points.
pH resolution during calibration.
Calibration Alarm Time-Out status:
if disabled.
CAL pH
BUF
CAL pH
BUF
CAL pH
BUF
CAL
BUF
CAL
CAL pH
BUF
CAL pH
BUF

14
CAL INTV
CAL
LOGGING FUNCTION
Up to 50 LOG samples can be stored into memory.
LOGGING THE CURRENT DATA
To store the current reading into memory press LOG while the instrument is in
measurement mode.
The instrument will display the current date (mm.dd) on the primary LCD, the
record number on the secondary LCD and LOG tag will blink for a few seconds
(see example below: record No. 5 dated September 14):
If there are less than 6 memory locations remaining, the record number and
Lo message will blink to alert the user.
If the log space is full, FULL LOC message will be displayed and no more
data will be saved.
LOG
LOG
LOG
or the number of days until the calibration alarm will be displayed.
or if expired (7 days ago).
The instrument ID.
Note: Press GLP at any moment and the instrument will return to
measurement mode.
If calibration has not been performed, the instrument displays
no CAL message blinking.

15
When LOG is pressed, a complete set of information is stored: date, time, pH,
mV, temperature and calibration data.
VIEW LOGGED DATA
Press RCL while in measurement mode to retrive the stored information.
If no data were logged, the instrument displays:
Otherwise, the instruments will display the pH or relative mV value on the
primary LCD and the last stored record number on the secondary LCD, along
with LOG tag.
or
Pressing the ARROW keys, the instrument will display the same parameter
but for a different record.
Press RANGE and the instrument will display the next logged parameter as
follows:
The mV value on the primary LCD and the record number on the secondary
LCD.
The temperature value on the primary LCD and the record number on
the secondary LCD.
Note: When the pH, mV or temperature is displayed, if SET/CLR is pressed
and hold down, the secondary LCD will display the record date.
LOG
LOG pH
LOG pH
LOG mV
LOG
C
mVLOG

16
LOG DATE
LOG mV
 The time on the primary LCD, along with TIME tag.
 The date on the primary LCD, along with DATE tag.
The calibration offset on the primary LCD and OFS message on the
secondary LCD.
The calibration slope on the primary LCD and SLP message on the
secondary LCD.
Note: If in Relative mV RECALL mode, the instruments will display ----
message on the primary LCD.
When the time, date, year, offset or slope is displayed, if SET/CLR
is pressed and hold down, the secondary LCD will display the record
number.
The dEL message on the primary LCD and the selected record on the
secondary LCD, along with LOGtag.
Note: If one of the ARROW keys is pressed while dEL and record
number is displayed, the next/previous record number is selected.
If LOG is pressed, the secondary LCD will display ALL message.
Pressing LOG again, the secondary LCD will display the record
number.
Press SET/CLR to delete the selected or all records.
LOG TIME
%
LOG
LOG
LOG

17
LOG
If del ALL option was selected, all records are deleted and the
instrument returnsto measurement mode.
Note:After LOG is pressed while in measurement mode or a selected record is
deleted, the instrument will display the amount of free log space for about
one second (e.g. 25 records free).
Press RCL to leave RECALL mode at any time.
SETUP
Setup mode allows viewing and modifying the following parameters:
Current Time
Current Date
pH Resolution
Beep Status
Baud Rate (serial communication)
Command prefix (serial communication)
Calibration Alarm Time-Out
Instrument ID
To enter SETUP mode press SET while the instrument is in measurement mode.
Select a parameter with the ARROW keys.
Press CAL if you want to change a parameter value. The selected parameter
will start blinking.
Press RANGE to toggle between displayed parameters.
Press the ARROW keys to increase or decrease the displayed value.
Press CFM to save the modified value or CAL to escape.
Press the ARROW keys to select the next/previous parameter.
CURRENT TIME SET
Press CAL when the current time is displayed. The hour will start blinking.
Press the ARROW keys to change the hour.
Press RANGE. The minutes will start blinking.
TIME
TIME

18
Press the ARROW keys to change the minutes.
Press CFM to save the modified value.
Press CAL to escape without saving.
CURRENT DATE SET
Press CAL when the current date is displayed. The year will start blinking.
Press the ARROW keys to change the year.
Press RANGE. The month will start blinking.
Press the ARROW keys to change the month.
Press RANGE. The day will start blinking.
Press the ARROW keys to change the day.
Press CFM to save the modified value.
Press CAL to escape without saving.
pH RESOLUTION SET
Press CAL when the pH range is displayed. The pH range (0.1, 0.01 or
0.001) will start blinking.
Press the ARROW keys to change the pH range.
Press CFM to save the modified pH range.
Press CAL to escape without saving.
DATE
DATE
DATE
pH

19
BEEP STATUS SET
Press CAL when the beep status is displayed. Beep status (On or OFF) will
start blinking.
Press the ARROW keys to change the beep status (On or OFF).
Press CFM to save the modified beep status.
Press CAL to escape without saving.
BAUD RATE SET
Press CAL when the baud rate is displayed. The baud rate (600, 1200, 2400,
4800 or 9600) will start blinking.
Press the ARROW keys to change the baud rate value.
Press CFM to save the modified baud rate value.
Press CAL to escape without saving.
SERIAL COMMUNICATION COMMAND PREFIX SET
Press CAL when the command prefix is displayed. The command prefix (0 to
47) will start blinking.
Press the ARROW keys to change the command prefix.
Press CFM to save the modified command prefix value.
Press CAL to escape without saving.
Note:  See the PC interface section on page 25 for a complete explanation.
 The command prefix must be 16 if HI 92000 PC software is used.
CALIBRATION ALARM TIME-OUT SET
Press CAL when the calibration time-out is displayed. Calibration time-out
(OFF or 1 to 7 days) will start blinking.
CAL INTV

20
Press the ARROW keys to change the calibration time-out value.
Press CFM to save the modified calibration time-out value.
Press CAL to escape without saving.
INSTRUMENT ID PARAMETER SET
Press CAL when the instrument ID is displayed. The instrument ID (0000 to
9999) will start blinking.
Press the ARROW keys to change the instrument ID value.
Press CFM to save the modified instrument ID value.
Press CAL to escape without saving.
Note: The instrument ID is downloaded to a PC as part of a logged data, set
to identify its origin.