User manual HANNA INSTRUMENTS HI 9145

[. . . ] 4 Functional Description - Meter. . . . . . . . . . . . . . . . . . . . . 5 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Probe Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [. . . ] the membrane is filled with electrolyte, probe is connected to the meter and properly polarized. · "COND" appears on the display to inform the user that ON/OFF the probe is in auto-conditioning (automatic polarization) mode. · Once "COND" disappears, the probe is polarized and the instrument can be calibrated. · · · Press CAL. The disply shows "----" together with the "CAL" symbol to indicate that the instrument is in calibration mode. The instrument will automatically standardize itself to the actual saturation value. 1 minute it will display "100%" with "SAMPLE" to indicate that the calibration is complete. CAL CAL SAMPLE % °C · HI 9143 only: press FACTOR and ensure that F1 and F2 are set to the appropriate altitude and salinity values. Notes: · The instrument must be calibrated whenever the probe, membrane or electrolyte is changed. · To exit the calibration mode at any time, press CAL. CAL · The display may be switched from readings in % saturation to ppm (mg/L) by simply RANGE pressing the RANGE key. Recalibration is not needed. 8 9 TAKING MEASUREMENTS Make sure the meter has been calibrated and the protective cap has been removed. Immerse the tip of the probe in the sample to be tested ensuring that the temperature sensor is also immersed. To display values in % saturation, press RANGE. RANGE For accurate dissolved oxygen measurements, a water movement of at least 30 cm (12")/sec is required. This is to ensure that oxygen depleted on the membrane surface is constantly replenished. A moving stream will provide adequate circulation. During field measurements, this condition may be obtained by manually stirring the probe. Accurate readings are not possible while the liquid is stationary. During laboratory measurements, the use of a magnetic stirrer to ensure a certain agitation of the fluid is recommended. This way, any errors due to the presence of air bubbles on the menbrane surface are minimized. For accurate measurements, allow sufficient time for the thermal equilibrium to be reached between the probe and the measured sample (a few minutes if the temperature difference is several degrees). mg/L READINGS The mg/L mode give the dissolved oxygen concentration directly in ppm. If the sample contains significant salinity or if the measurement is taken at a higher altitude than sea level, the readout values must be corrected, by taking into account the lower degree of oxygen solubility in such conditions. Compensation for altitude and sality effects is possible with the HI 9143 model. Altitude and/or salinity values should be set before calibrating and taking measurements. The meter will automatically compensate for these factors (see "Altitude Compensation" and "Salinity Compensation" sections). [. . . ] (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. 7118 · Fax 6291. 6906 South Africa: Tel. [. . . ]