Hanna Instruments HI 254 User Manual
Instruction Manual
HI 254
Microprocessor-Based
pH/mV/ºC
Bench Meter
www.hannainst.com
1
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
tech@hannainst.com or turn to the back cover for our worldwide contact list.
This instrument is in compliance with directives.
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 Authorization 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.
TABLE OF CONTENTS
WARRANTY ......................................................................................................................... 2
PRELIMINARY EXAMINATION .............................................................................................. 3
GENERAL DESCRIPTION ..................................................................................................... 3
FUNCTIONAL DESCRIPTION ................................................................................................ 4
HI 254 SPECIFICATIONS .................................................................................................... 5
OPERATIONAL GUIDE ......................................................................................................... 6
pH CALIBRATION ................................................................................................................ 9
GOOD LABORATORY PRACTICE (GLP) ...................................................................................12
LOGGING FUNCTION ..............................................................................................................14
SETUP .....................................................................................................................................17
TEMPERATURE CALIBRATION (for technical personnel only) ........................................... 21
mV CALIBRATION (for technical personnel only) .............................................................. 23
RELATIVE mV CALIBRATION .............................................................................................. 24
PC INTERFACE .................................................................................................................... 25
pH VALUES AT DIFFERENT TEMPERATURES .................................................................... 27
ELECTRODE CONDITIONING & MAINTENANCE .................................................................. 28
TROUBLESHOOTING GUIDE ............................................................................................... 31
TEMPERATURE CORRELATION FOR pH SENSITIVE GLASS ............................................... 32
ACCESSORIES ...................................................................................................................... 33
2
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.
GENERAL DESCRIPTION
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 users request for later
retrieval.
Hanna Instruments reserves the right to modify the design, construction
and appearance of its products without advance notice.
3
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 mVpH
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 GLPData
StoreLog Data
Set Instrument Parameters
Clear Calibration/Log Data
Recall Log Data
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.
4
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HI 254
SPECIFICATIONS
5
OPERATIONAL GUIDE
pH
C
pH
C
C
CAL
CFM
READY
BUF
WRONG
LOG mV pH
TIME% DATE INTV
BUFFER pH
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 electrodes 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 has been 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.
6
If measurements are taken successively in different samples, it is recommended
C
C C
mV
C
mV
C
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 theºC 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.
7
RELATIVE mV MEASUREMENTS
mV
C
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.
8
pH CALIBRATION
BUF
CAL
BUFFER pH
BUF
pH
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
and the 7.01 buffer will be displayed on the
secondary LCD.
tags will appear
If necessary, press the ARROW keys to select a different buffer value.
9
The tag will blink on the LCD until the reading is
CAL
BUF
pH
BUFFER pH
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.
10
If necessary, press the ARROW keys to select a different buffer value.
BUF
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 measurement 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
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 Procedure (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.
11
GOOD LABORATORY PRACTICE (GLP)
TIME
CAL
DATE
CAL
CAL mV
%
CAL
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).
12
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