User manual HANNA INSTRUMENTS HI 21

[. . . ] HI 21/HI 22 Series Wall-mounted, Microprocessor-based Process pH/mV Meters Instruction Manual Dear Customer, Thank you for choosing a Hanna Product. Please read this instruction manual carefully before using the instrument. It will provide you with the necessary information for the 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 tech@hannainst. com. [. . . ] pH CALIBRATION (for HI 21 Series only) The pH controller can be calibrated through a one-point, two-point or three-point calibration. You do not need to enter the method chosen, simply exit the calibration mode, by pressing CAL, when the desired number of points has been calibrated. The calibration points for HI 21 are pH 4. 01, pH 7. 01 and pH 10. 01 (at 25°C). The sequence proposed by the controller is pH 7. 01, pH 4. 01, pH 10. 01. However, the user can change this sequence by means of the ñ and ò keys. The electrode must be kept hydrated at all times and definitely prior to calibration. The temperature probe should also be connected to the process meter. The meters are equipped with a stability indicator. The user is also guided with indications on the display during the calibration procedure. Initial Preparation Pour small quantities of pH 7. 01 (HI 7007) and pH 4. 01 (HI 7004) and/or pH 10. 01 (HI 7010) solutions into individual beakers. If possible, use plastic beakers to minimize any EMC interference. HI 7004 HI 70 04 The items in the Data field are separated by blanks. Buf 3 if only a two points calibration was performed) it is replaced by the "N" character. HI 7007 Note The "r485" message can appear on the LCD while the controller is receiving or answering commands. SETTING THE BAUD RATE The transmission speed (baud rate) of the meter and external device must be the same. To change this value, use setup item 71. 34 35 For accurate calibration, use two beakers for each buffer solution, the first one for rinsing the electrode, the second one for calibration. By doing this, contamination between the buffers is minimized. RINSE CALIBRATION · Remove the protective cap from the pH electrode and immerse it into the selected buffer solution (e. g. pH 7. 01) with the Potential Matching Pin and temperature probe, then stir gently. Note HI 7007 HI 7007 To obtain accurate readings, use pH 7. 01 and pH 4. 01 if you measure acidic samples, or pH 7. 01 and pH 10. 01 for alkaline measurements or perform a 3-point calibration for the entire range. One Point Calibration (Offset) · To perform the pH calibration enter the calibration mode, by pressing CAL and entering the password. · After the correct password is entered, the control actions stop and the primary LCD will display the pH value using the current offset and slope, with the "CAL" and " " indicators lit and the probe indicator " " blinking. The value displayed on the secondary LCD is the buffer value at the actual temperature. 1 The electrode should be submerged approximately 4 cm (1½") in the solution. The temperature probe should be located as close as possible to the pH electrode. When it is not possible to immerse the Potential Matching Pin together with the pH electrode in the solution, disable the differential input by connecting the Connection for Potential Matching Pin (#5 page 7) with the Connection for Electrode Reference (#6 on page 7) with a jumper wire. · Only when the reading is stable the probe indicator " " will stop flashing (after about 30 seconds) and the "CFM" indicator will start blinking. [. . . ] This can be achieved by installing the electrode in such a way that it is constantly in a well filled with the sample (stream or tank). The protective cap can also be filled with HI 70300 Storage Solution if the electrode is not being used at all. With industrial applications, it is always recommended to keep at least one spare electrode handy. When anomalies are not resolved with a simple maintenance, change the electrode to see if the problem is alleviated. ELECTRODE STORAGE SOLUTIONS HI 70300M Storage Solution, 230 mL HI 70300L Storage Solution, 460 mL ELECTRODE CLEANING SOLUTIONS HI 7061M General Cleaning Sol. , 230 mL HI 7061L General Cleaning Sol. , 460 mL HI 7073M Protein Cleaning Sol. , 230 mL HI 7073L Protein Cleaning Sol. , 460 mL HI 7074M Inorganic Cleaning Sol. , 230 mL HI 7074L Inorganic Cleaning Sol. , 460 mL HI 7077M Oil & Fat Cleaning Sol. , 230 mL HI 7077L Oil & Fat Cleaning Sol. , 460 mL REFILL ELECTROLYTE SOLUTIONS HI 7071 3. 5M KCl+AgCl Electrolyte, 4x50 mL, for single junction electrodes HI 7072 1M KNO3 Electrolyte, 4x50 mL HI 7082 3. 5M KCl Electrolyte, 4x50 mL, for double junction electrodes 62 63 RECOMMENDED pH ELECTRODES (All electrodes gel-filled and with ceramic junction unless otherwise indicated). [. . . ]