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SOP for Operation and Calibration of Field Water Quality Instruments 5 <br />2. Turn on the meter and allow 15 minutes of warm up time before calibration. <br />3. Ensure that the sponge inside the probe chamber is moist. <br />4. If the stream is narrow, manually suspend the probe in the approximate center of the thalweg. If the <br />stream is wider, suspend the probe from the end of the swing sampler, to reach the approximate center <br />of the thalweg. If it is necessary to enter the water to measure DO at the required location, don waders <br />and enter the stream, approaching the monitoring station from downstream, and suspend the probe <br />manually by hand. <br />5. Slowly and continuously move the probe through the water. <br />6. Allow the temperature and DO readings to stabilize. <br />7. Observe /record temperature ( °C) and DO (mg/1). <br />8. Press MODE and record % saturation. <br />9. Rinse the probe with distilled water after each use, and replace in the probe chamber. <br />3.5 Oxidation Reduction Potential (ORP) <br />Oxidation reduction potential (ORP) meters are available from several manufactures. The information <br />provided below is directly applicable to the EcoSense® pH 100 and may be generally relevant to other ORP <br />meter makes and models. <br />3.5.1 Calibration <br />The combination mV electrode is factory calibrated and tested by EcoSense® and does not require specific <br />calibration to measure ORP. The ORP meter will be operated as instructed in the instrument manual <br />(EcoSense(& pH100 Operations Manual, attached). The condition of the probe will be checked prior to each <br />measurement. <br />3.5.2 Field Operation <br />1. Connect the combination mV electrode to the EcoSense® pH100 <br />Press Mode to enter the mV mode with the Autolock feature on or off as desired. For unstable <br />samples the unit will not be able to Autolock; in this case turn the Autolock feature off. <br />3. Rinse the electrode with distilled water and immerse it in the sample to be measured. <br />4. If the Autolock feature is on, press the MEA/EFF button. The meter will flash WAIT; once the <br />reading has stabilized record the reading in the fieldbook. If the Autolock feature is off, allow <br />sufficient time for the reading to equilibrate to a stable value (f 1 mV.) <br />5. Rinse the probe with distilled water after each use, place one -half inch of distilled water or 4.01 <br />calibration solution in the cap, and tighten cap. <br />4. CALIBRATION SOLUTIONS <br />Calibration solutions will not be reused, and will be renewed prior to expiration dates stamped on <br />manufacturer's container. Equipment calibration ensures that measurements obtained are accurate with <br />reference to a known standard. <br />5. REPORTING <br />Record all instrument makes and models, procedures, calibration results, and equipment modifications for each <br />meter. Laboratory calibration logs, equipment maintenance logs, and equipment manuals are kept on file at <br />Whetstone Associates, Inc. Field calibration and maintenance records will be kept in the fieldbook and/or on <br />the field sampling data sheets. <br />4153A.140129 Whetstone Associates <br />