Instruction Manual HI 250 HI 251 Microprocessor-Based pH/mV/ºC Bench Meters w w w. h a n n a i n s t .
Dear Customer, Thank you for choosing a Hanna Instruments product. Please read this instruction manual carefully before using the instruments. This manual will provide you with the necessary information for correct use of the instruments, as well as a precise idea of their 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. These instruments are in compliance with directives.
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.
FUNCTIONAL DESCRIPTION Primary LCD Secondary LCD Front Panel CAL LOG 1 % TIME DATE INTV BUFFER pH C mV pH CFM 1 READY 2 WRONG BUF 3 10 2 Functions 3 4 CAL CFM GLP 5 Show GLP Data Store Log Data / RCL Recall Log Data CFM RANGE 6 C C LOG RCL pH Calibration - 3 points GLP LOG SET/CLR CAL Select pH Buffer RANGE Confirm Calibration in selected pH Buffer Select pH/ORP/Rel mV Scroll Log Data Set Instrument Parameters Clear Calibration/Log Data 7 9 Start/Exit Calibration 8 SET CLR
HI 250 SPECIFICATIONS RANGE 2.0 to 16.0 p H 2.00 to 16.00 p H RE SOL UTION 0.1 p H 0.01 p H 9.9 to 120.0 ºC 0.1 ºC ±0.1 p H ±0.01 p H ACCURACY @ 20 °C/68 °F ±0.4 ºC (exclud ing p rob e error) Comp uter interfa ce op to-isola ted RS232 p H Ca lib ra tion 1, 2 or 3 point calibration, 5 buffers available (4.01, 6.86, 7.01, 9.18, 10.01) Temp era ture comp ensa tion Ma nua l or Automa tic from: 9.9 to 120.
HI 251 SPECIFICATIONS 2.0 to 16.0 p H 2.00 to 16.00 p H ±699.9 m V ±2000 m V RANGE 9.9 to 120.0 ºC 0.1 p H 0.01 p H 0.1 m V (±699.9 m V) 1 m V (±2000 m V) RE SOL UTION 0.1 ºC ±0.1 p H ±0.01 p H ACCURACY @ 20 °C/68 °F ±0.2 m V (±699.9 m V) ±1 m V (±2000 m V) ±0.4 ºC (exclu d in g p rob e error) Rel m V offset ra n g e ±2000 m V Com p u ter in terfa ce op to-isola ted RS232 p H Ca lib ra tion 1, 2 or 3 point calibration, 5 buffers available (4.01, 6.86, 7.01, 9.18, 10.
OPERATIONAL GUIDE POWER CONNECTION Plug the 12 VDC adapter into the power supply socket. Note: These instruments use 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.
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.
RELATIVE mV MEASUREMENTS (HI 251 only) 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. mV C 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.
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.
The tag will blink on the LCD until the reading is stable. When the reading is stable and close to the selected buffer, READY tag will be displayed and 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. CAL pH BUFFER pH BUF 2 Note: The instruments will automatically skip the buffer used for the first point. It also skips 6.86 if 7.01 buffer was used and viceversa.
Note: If the value measured by the instruments 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.
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 last calibration (one, two or three-point) is stored for the user to review when necessary. This data includes the following: calibration time stamp, offset (mV), slope (%), calibration buffers and the time until a new calibration is required.
The calibration buffers in calibrating order. The first pH calibration buffer: CAL pH BUF The second pH calibration buffer: CAL pH BUF The third pH calibration buffer: CAL pH BUF 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).
The instrument ID. Note: Press GLP at any moment and the instruments will return to measurement mode. If calibration has not been performed, the instruments display no CAL message blinking. 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 instruments are in measurement mode. The instruments will display the current date (mm.
VIEW LOGGED DATA Press RCL while in measurement mode to retrive the stored information. If no data were logged, the instruments display: LOG Otherwise, the instruments will display the pH or relative mV value (HI 251 only) on the primary LCD and the last stored record number on the secondary LCD, along with LOG tag. LOG pH or LOG mV Pressing the ARROW keys, the instruments will display the same parameter but for a different record.
The date on the primary LCD, along with DATE tag. DATE LOG The calibration offset on the primary LCD and OFS message on the secondary LCD. LOG mV The calibration slope on the primary LCD and SLP message on the secondary LCD. % LOG Note: If in Relative mV RECALL mode, the instruments will display ---- message on the primary LCD (HI 251 only). 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.
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 instruments are 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.
CURRENT DATE SET Press CAL when the current date is displayed. The year will start blinking. DATE Press the ARROW keys to change the year. Press RANGE. The month will start blinking. DATE Press the ARROW keys to change the month. Press RANGE. The day will start blinking. DATE 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 (0.01 or 0.1) 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.
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.
TEMPERATURE CALIBRATION (for technical personnel only) All the instruments are factory calibrated for temperature. Hannas temperature probes are interchangeable and no temperature calibration is needed when they are replaced. If the temperature measurements are inaccurate, temperature recalibration should be performed. For an accurate recalibration, contact your dealer or the nearest Hanna Customer Service Center, or follow the instructions bellow.
Use the ARROW keys to set the reading on the secondary LCD to that of the hot water. C C When the reading is stable and close to the selected calibration point, READY tag will appear and CFM tag will blink. Press CFM to confirm. The instruments return to measurement mode. Note: If the reading is not close to the selected calibration point, WRONG tag will blink. Change the temperature probe and restart calibration.
Note: If the reading is not close to the selected calibration point, WRONG tag will blink. Verify calibration condition or contact your vendor if you can not calibrate. Press CAL in any moment of the calibration process. The instruments will return to measurement mode. If calibration process is stopped after 600 mV is confirmed, the 600 mV range is calibrated and calibration parameters are memorized.
PC INTERFACE Data transmission from the instrument to the PC can be done with the HI 92000 Windows® compatible software (optional). HI 92000 also offers graphing and on-line help feature. Data can be exported to the most popular spreadsheet programs for further analysis. To connect your instrument to a PC, use the optional Hanna HI 920010 cable connector. Make sure that your instrument is switched off and plug one connector to the instrument RS232C socket and the other into the serial port of your PC.
CHR n Change the instrument range according with the parameter value (n): n=1 pH range/0.01 resolution n=2 pH range/0.1 resolution n=3 mV range (HI 251 only) n=4 Relative mV range (HI 251 only) COMMANDS REQUIRING AN ANSWER Causes the instrument to send the pH reading. If the range is set to mV, Err6 is received. MV? Causes the instrument to send the mV reading. If the range is set to pH, Err6 is received. MR? Causes the instrument to send the relative mV reading.
pH VALUES AT DIFFERENT TEMPERATURES The temperature has an effect on pH. The calibration buffer solutions are affected by temperature changes to a lesser degree than normal solutions. During calibration the instrument will automatically calibrate to the pH value corresponding to the measured or set temperature. TEMP pH VALUES ºC ºF 4.01 6.86 7.01 9.18 10.01 0 32 4.01 6.98 7.13 9.46 10.32 5 41 4.00 6.95 7.10 9.39 10.24 10 50 4.00 6.92 7.07 9.33 10.18 15 59 4.00 6.90 7.
ELECTRODE CONDITIONING & MAINTENANCE PREPARATION PROCEDURE Remove the protective cap of the pH electrode. DO NOT BE ALARMED IF SALT DEPOSITS ARE PRESENT. This is normal with electrodes. They will disappear when rinsed with water. During transport, tiny bubbles of air may form inside the glass bulb affecting proper functioning of the electrode. These bubbles can be removed by shaking down the electrode as you would do with a glass thermometer.
For refillable electrodes: If the filling solution (electrolyte) is more than 2½ cm (1) below the fill hole, add HI 7082 or HI 8082 3.5M KCl Electrolyte Solution for double junction or HI 7071 or HI 8071 3.5M KCl+AgCl Electrolyte Solution for single junction electrodes. For faster response, unscrew the fill hole screw during measurements. For AMPHEL ® electrodes: If the electrode does not respond to pH changes, the battery is run down and the electrode should be replaced.
CLEANING PROCEDURE General Soak in Hanna HI 7061 or HI 8061 General Cleaning Solution for approximately ½ hour. Protein Soak in Hanna HI 7073 or HI 8073 Protein Cleaning Solution for 15 minutes. Inorganic Soak in Hanna HI 7074 Inorganic Cleaning Solution for 15 minutes. Oil/grease Rinse with Hanna HI 7077 or HI 8077 Oil and Fat Cleaning Solution.
TROUBLESHOOTING GUIDE SYMPTOMS Slow reponse/excessive drift. PROBLEM D irty p H electrod e. Rea d ing s fluctua te up Clog g ed /d irty junction. a nd d own (noise). L ow electrolyte level (refilla b le electrod es only). Out of ra ng e in the mV sca le. D ry memb ra ne/junction. The meter d oes not a ccep t the b uffer solution for ca lib ra tion. Out of ord er p H electrod e. If the d isp la y shows: "p H" a nd " -2.00" or "16.00" b linking .
TEMPERATURE CORRELATION FOR pH SENSITIVE GLASS The resistance of glass electrodes partially depends on the temperature. The lower the temperature, the higher the resistance. It takes more time for the reading to stabilize if the resistance is higher. In addition, the response time will suffer to a greater degree at temperatures below 25 ºC. Since the resistance of the pH electrode is in the range of 50 200 Mohm, the current across the membrane is in the pico Ampere range.
ACCESSORIES pH BUFFER SOLUTIONS HI 70004P HI 70007P HI 70010P HI 7001L HI 7004L HI 7006L HI 7007L HI 7009L HI 7010L HI 7001L HI 8004L HI 8006L HI 8007L HI 8009L HI 8010L pH 4.01 Buffer Sachets, 20 mL, 25 pcs pH 7.01 Buffer Sachets, 20 mL, 25 pcs pH 10.01 Buffer Sachets, 20 mL, 25 pcs pH 1.68 Buffer Solution, 500 mL pH 4.01 Buffer Solution, 500 mL pH 6.86 Buffer Solution, 500 mL pH 7.01 Buffer Solution, 500 mL pH 9.18 Buffer Solution, 500 mL pH 10.01 Buffer Solution, 500 mL pH 1.
ORP PRETREATMENT SOLUTIONS HI 7091L Reducing Pretreatment Solution, 460 mL HI 7092L Oxidizing Pretreatment Solution, 460 mL pH ELECTRODES All electrodes part numbers ending in B are supplied with a BNC connector and 1 m (3.3') cable, as shown below : HI 1043B Glass-body, double junction, refillable, combination pH electrode. Use: strong acid/alkali. 9.5mm DIA 0.37" 12 mm 0.5" HI 1043 120 mm 4.7" "S" VERSION HI 1053B Glass-body, triple ceramic, conic shape, refillable, combination pH electrode.
HI 1330B Glass-body, semimicro, single junction, refillable, combination pH electrode. Use: laboratory, vials. 5mm DIA 0.2" 5mm 0.2" HI 1330 120 mm 4.7" "S" VERSION HI 1331B Glass-body, semimicro, single junction, refillable, combination pH electrode. Use: flasks. HI 1310 8 mm 0.3" 7.5mm DIA 0.29" HI 1331 210 mm 8.25" "S" VERSION HI 1230B Plastic-body (Ultem®), double junction, gel-filled, combination pH electrode. Use: general, field. HI 1311 12 mm 0.5" HI 1230 120 mm 4.
FC 100B Plastic-body (Kynar®), double junction, refillable, combination pH electrode. Use: general purpose for food industry. 12 mm 0.5" FC 100 120 mm 4.7" FC 200B Plastic-body (Kynar®), open junction, conic, Viscolene, non-refillable, combination pH electrode. Use: meat & cheese. 6 mm 0.25" FC 200 75 mm 2.95" FC 210B Glass-body, double junction, conic, Viscolene, non-refillable, combination pH electrode. Use: milk, yogurt. 12 mm 0.5" FC 210 120 mm 4.
HI 1413B Glass-body, single junction, flat tip, Viscolene, non-refillable, combination pH electrode. Use: surface measurement. 12 mm 0.5" HI 1413 110 mm 4.3" ORP ELECTRODES HI 3131B Glass-body, refillable, combination platinum ORP electrode. Use: titration. 12 mm 0.5" HI 3131 150 mm 5.9" "S" VERSION HI 3230B Plastic-body (Ultem®), gel-filled, combination platinum ORP electrode. Use: general purpose. HI 3111 12 mm 0.5" HI 3230 120 mm 4.
EXTENSION CABLE FOR SCREW-TYPE ELECTRODES (SCREW TO BNC ADAPTER) HI 7855/1 Extension cable 1 m (3.3') long HI 7855/3 Extension cable 3 m (9.9') long HI 7855 SERIES CABLE CONNECTORS CONNECTOR AND 3.0 mm (0.
RECOMMENDATIONS FOR USERS Before using these products, make sure they are entirely suitable for the environment in which they are used. Operation of these instruments in residential areas could cause unacceptable interferences to radio and TV equipment, requiring the operator to follow all necessary steps to correct interferences. The glass bulb at the end of the pH electrode is sensitive to electrostatic discharges. Avoid touching this glass bulb at all times.
SALES AND TECHNICAL SERVICE CONTACTS Australia: Tel. (03) 9769.0666 Fax (03) 9769.0699 China: Tel. (10) 88570068 Fax (10) 88570060 Egypt: Tel. & Fax (02) 2758.683 Germany: Tel. (07851) 9129-0 Fax (07851) 9129-99 Greece: Tel. (210) 823.5192 Fax (210) 884.0210 Indonesia: Tel. (21) 4584.2941 Fax (21) 4584.2942 Japan: Tel. (03) 3258.9565 Fax (03) 3258.9567 Korea: Tel. (02) 2278.5147 Fax (02) 2264.1729 Malaysia: Tel. (603) 5638.9940 Fax (603) 5638.9829 Singapore: Tel. 6296.
