These pH/ORP/Temperature bench meters monitor the pH electrode and buffer solutions. These meters warn the user in the event the pH electrode is dirty and if the calibration buffer is out of specification (cross-contamination). When a pH electrode is not properly cleaned, even the smallest residue of samples left on the sensitive glass can produce slope errors up to a tenth of a pH unit. A pH buffer solution that has been contaminated can also drift by a few tenths of a pH unit, resulting in erroneous calibration. Dirty pH electrodes and buffer solutions cannot be detected by conventional pH meters, resulting in wrong calibrations and subsequent erroneous pH measurements. Hanna’s new pH meters have addressed this problem by displaying symbols on the LCD that warn the user to clean or replace the buffer solution with a fresh one. This new calibration concept removes the guesswork and guarantees the user that the equipment is in the best condition.
Both instruments have a “log on demand” function to record 100 (pH 221) or 500 (pH 223) readings, RS232 port for computer connection, automatic or manual temperature compensation (ATC or MTC), and an extended range of 7 memorized calibration buffers. pH 221 offers a readout of 0.01 pH and pH 223 has a resolution of 0.001 pH.