User Guide Waterproof Palm pH Meter Model PH220 7.
Introduction Congratulations on your purchase of the Extech PH220 waterproof pH/mV meter. This microprocessor-based device with tactile push-buttons is battery operated and ideal for field use. The PH220 simultaneously displays pH and temperature. The rubber holster which protects the meter has a magnetic backing for convenient mounting. The built-in memory (25 readings) allows STORE, RECALL, and CLEAR functionality. Careful use of this meter will provide years of reliable service.
Meter Description 1. 2. 3. 4. 5. 1 Battery Compartment (under holster) Rubber Holster LCD Display Function buttons Electrode input 2 7.00 3 4 5 Basic Display Description 1. 2. 3. 4. 5. Measurement value Battery status Units of measure Temperature units Solution temperature 1 3 2 4 5 Note that there are other more specialized displays that appear on the LCD that have not been included in this basic operation display description.
Calibration (pH) The sensitivity of a pH electrode degrades over time, it is very important to frequently calibrate the meter to the electrode. pH electrodes can be thought of as batteries in that they run down with time and use. Calibration is performed using standard buffer solutions at room temperature (78°F, 25°C). Buffer solutions are solutions of a known pH that have the useful property of resisting changes in pH.
Measuring pH Electrodes should always be rinsed before and between samples with distilled or DI (de-ionized) water to remove all traces of storage solution, process media, or previous test solution. 1. 2. 3. 4. 5. 6. 7. 8. Connect the pH electrode to the meter. Turn the meter on using the on/off button . Wait for the self test (‘SLF tSt’) to finish. Use the MODE button to select pH mode. The unit of measure appears on the LCD.
Storing and Recalling Readings This instrument has the ability to store up to 25 measurement readings. At a later time the readings can be recalled and viewed. Readings are saved even after the instrument has been turned off. STORE Readings The steps below cover the STORE process in detail: 1. Take a measurement as described earlier in this manual. 2. Momentarily press the STORE/RECALL button to save the reading. The reading will be held on the display (the HOLD and STORE icons will appear).
Battery Replacement The 9 volt alkaline battery that powers the instrument requires replacing when all battery icon ‘fill bars’ are depleted. To replace the battery follow the steps below: 1. 2. 3. 4. 5. 6. Disconnect the electrode from the instrument. Remove the instrument’s protective jacket by pulling it over the top of the meter (ensure that the electrode is disconnected). Pry the battery compartment up from the top of the meter using a screwdriver or coin at one of the two indentations (see diagram).
Electrode Maintenance and Troubleshooting Most pH measurement difficulties are caused by the electrode. Careful handling and proper storage of the electrode will increase measurement accuracy and electrode life. Electrodes should be rinsed to remove all traces of storage solution, process medium, or previous test solution. Electrode Storage The electrode should be stored in a soaker bottle or wetting cap filled with pH4 buffer.
