Instruction Manual HI 9142 Portable Waterproof Dissolved Oxygen Meter This instrument is in Compliance with the CE Directives http://www.hannainst.com Dear Customer, Thank you for choosing a Hanna Instruments Product. Please read this instruction manual carefully before using the instrument. This manual will provide you with all the necessary information for the correct use of the instrument, as well as a precise idea of its versatility in a wide range of applications. This instrument is in compliance with tives EN 50081-1 and 50082-1. direc- PRELIMINARY EXAMINATION Remove the instrument from the packing material and examine it to make sure that no damage has occurred during shipping. If there is any damage, notify your Dealer. In addition to this manual you should find the following items: · D.O. meter · 4 x 1.5V AA batteries · DO Probe (HI 76407/4) · Membrane cap (HI 76407A) · Protective cap · 30 mL electrolyte solution (HI 7041S) · Rugged carrying case Note: Save all packing material until you are sure that the instrument functions correctly. All defective items must be returned to us in the original packaging with the supplied accessories. TABLE OF CONTENTS Preliminary Examination ............................. 1 General Description ..................................... 1 Functional Description Probe ...................... 2 Functional Description Meter ....................... 3 Specifications ............................................. 4 Initial Probe Preparation .............................. 5 Calibration Procedure .................................. 6 Taking Measurements ................................. 8 Altitude and Salinity Compensation ............. 9 Probe & Membrane Maintenance .............. 11 Battery Replacement ................................ 13 Accessories .............................................. 14 Warranty ................................................... 15 Other Products from Hanna ....................... 16 CE Declaration of Conformity .................... 17 GENERAL DESCRIPTION Hanna Instruments' HI 9142 is a water-resistant, Dissolved Oxygen meter with Automatic Temperature Compensation. It has been developed for dissolved oxygen measurement in water and wastewater applications as well as other applications such as fish farming. Dissolved oxygen is indicated in tenths of parts per million (ppm=mg/l) . Four 1.5V AA batteries provide power and make the instrument completely portable. The meter is housed in a rugged water-resistant case for maximum protection in the field as well as in the laboratory. ISO 9000 Certified Company since 1992 The dissolved oxygen probe has a membrane covering the polarographic sensors and a built1 in thermistor for temperature measurements and compensation. The thin permeable membrane isolates the sensor elements from the testing solution, but allows oxygen to enter. When a voltage is applied across the sensor, oxygen that has passed through the membrane reacts causing current to flow, allowing the determination of oxygen. FUNCTIONAL DESCRIPTION PROBE FUNCTIONAL DESCRIPTION 3 1 4 6 7 8 4 9 5 6 7 8 9 2 10 1. 2. 3. 4. 5. 6. 7. Battery Compartment Probe Connector Liquid Crystal Display ON/OFF Button Calibration Button Slope Calibration Trimmer Zero D.O. Calibration Trimmer 1. D.O. Probe 2. Protective Cap 3. Water-tight Shielded Cable 4. Polypropylene Probe Body 5. Temperature Sensor 6. O-Ring Seal 7. Silver Chloride Anode 8. Platinum Cathode (sensor) 9. Oxygen Permeable PTFE Membrane 10.Membrane Cap 2 3 SPECIFICATIONS INITIAL PROBE PREPARATION Probe Preparation All probes shipped from Hanna Instrument are dry. To hydrate the probe and prepare it for use, connect it to the meter and proceed as follows. 1 Remove the red and black plas- Shipping cap tic cap. This cap is for shipping purposes and can be thrown away. black 2 Wet the sensor by soaking the bottom 2½ cm (1") of the probe red in electrolyte (HI 7041S) for 5 minutes. 3 Rinse the membrane (HI 76407A supplied in the kit with the meter) with electrolyte while shaking it gently. Refill with clean electrolyte. 4 Gently tap the FILL FIRST sides of the membrane with THEN TAP your finger tip to ensure that no air bubbles remain trapped. THEN SCREW To avoid damBACK ON aging the membrane, do not tap the membrane directly on the bottom. 5 Place rubber O-Ring properly inside the membrane cap. 6 With the sensor facing down, screw the cap clockwise. Some electrolyte will overflow. When not in use and during polarization, place the protective cap supplied in the kit with the meter. 5 HI 9142 Range Resolution Accuracy Typical EMC Deviation Calibration Temperature Compensation Probe Battery Type Life Environment Dimensions Weight 0.0 to 19.9 mg/l 0.1 mg/l ±1.5% Full Scale ±0.8 mg/l with 4 m cable probe Manual on 2 points (zero and slope) Automatic from 0 to 30°C (32 to 86°F) HI 76407/4 polarographic with 4 m cable 4 x 1.5V AA 500 hours of continuous use 0 to 50°C (32 to 122°F); 100% RH 196x80x60 mm (7.7x3.1x2.4") 425 g (15 oz.); kit: 1.4 kg (3.1 lbs) 4 CALIBRATION PROCEDURE PROBE POLARIZATION The probe is under polarization with a fixed voltage of approximately 800 mV. Probe polarization is essential for stable measurements with the same recurring degree of accuracy. With the probe properly polarized, oxygen is continually "consumed" by passing through the sensitive diaphragm and dissolving in the electrolyte solution contained in the probe. If this operation is interrupted, the electrolyte solution continues to be enriched with oxygen until it reaches an equilibrium with the surrounding solution. Whenever measurements are taken with a nonpolarized probe, the oxygen level revealed is both that of the tested solution as well as that present in the electrolyte solution. This reading is incorrect The calibration is very simple and fast. · Make sure the probe is ready for measurements (see initial preparation at page 7), i.e. the membrane is filled with electrolyte and the probe is connected to the meter. · Switch the meter on by pressing the ON/OFF key Zero Calibration: · Dip the probe into HI 7040 zero oxygen solution and stir gently for 2-3 minutes. · Allow 2 minutes for the LCD readout to stabilize. · Adjust the zero D.O. calibration trimmer until the display reads "0.0". Note The zero calibration screw is located close to the probe connector. Slope Calibration: It is suggested to perform the slope calibration in satured air. · Rinse the probe in a large amount of clean water to remove any residual zero oxygen solution. · Dry the probe tip and allow a few minutes for the LCD readout to stabilize. · Press and hold the CAL key. · Adjust the slope trimmer on the top of the meter to read "100%" on the LCD (while still holding the CAL button). Note The slope calibration screw is located farthest from the probe connection. · Release the CAL key and the LCD will display the value in ppm of oxygen. CAL ON/OFF · For an accurate calibration, it is recommended that you wait at least 15 minutes to ensure precise conditioning of the probe. · Remove the protective cap from the D.O. probe. % The zero calibration of the HI 9142 is very stable, therefore this procedure needs only to be performed whenever the probe is replaced. However, because the slope calibration is more critical, it is recommended to perform this procedure every week. 6 7 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. Make sure the temperature sensor is also immersed. For accurate dissolved oxygen measurements a water movement of 0.3 m/sec is required at a minimum. This is to ensure that the oxygendepleted membrane surface is constantly replenished. A moving stream will provide adequate circulation. To quickly check if the water speed is sufficient, wait for the reading to stabilize and then move the D.O. probe. If the reading is still stable, the measurement conditions are right, while if the reading increases the water movement is not adequate. During field measurements, this condition may be met by manually agitating the probe. Accurate readings are not possible while the liquid is at rest. During laboratory measurements, the use of a magnetic stirrer to ensure a certain velocity in the fluid is recommended. In this way, errors due to the diffusion of the oxygen present in the air in the solution are reduced to a minimum. At all times, time necessary for thermal equilibrium to occur between the probe and the sample must be allowed (a few minutes for temperature difference of several degrees). ALTITUDE & SALINITY COMPENSATION If the sample contains salts or if you are performing the measurements at a different altitude than sea level, the readout values must be corrected, taking into account the lower degree of oxygen solubility. ALTITUDE COMPENSATION All the readouts are referred at sea level, thus the displayed measurements are higher than the actual values. In fact, altitude affects D.O. concentration decreasing its value. The following table reports the oxygen solubility at various temperatures and altitudes, based on sea level barometric pressure of 760 mm Hg. Altitude, Meters above Sea Level °C 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 0m 300 m 600 m 900 m 1200 m 1500m 1800m °F 32.0 35.6 39.2 42.8 46.4 50.0 53.6 57.2 60.8 64.4 68.0 71.6 75.2 78.8 82.4 86.0 89.6 93.2 96.8 100.4 104.4 14.6 13.8 13.1 12.4 11.8 11.3 10.8 10.3 9.9 9.5 9.1 8.7 8.4 8.1 7.8 7.5 7.3 7.1 6.8 6.6 6.4 14.1 13.3 12.7 12.0 11.4 10.9 10.4 9.9 9.7 9.2 8.8 8.4 8.1 7.8 7.5 7.2 7.1 6.9 6.6 6.4 6.2 13.6 12.9 12.2 11.6 11.0 10.5 10.1 9.6 9.2 8.7 8.5 8.1 7.8 7.5 7.3 7.0 6.8 6.6 6.3 6.2 6.0 13.2 12.4 11.9 11.2 10.6 10.2 9.7 9.3 8.9 8.6 8.2 7.8 7.5 7.3 7.0 6.8 6.6 6.4 6.1 5.9 5.8 12.7 12.0 11.4 10.8 10.3 9.8 9.4 9.0 8.6 8.3 7.9 7.7 7.3 7.0 6.8 6.5 6.4 6.2 5.9 5.7 5.6 12.3 11.6 11.0 10.4 9.9 9.5 9.1 8.7 8.3 8.0 7.7 7.3 7.1 6.8 6.6 6.3 6.1 6.0 5.7 5.6 5.4 11.8 11.2 10.6 10.1 9.6 9.2 8.8 8.3 8.0 7.7 7.4 7.1 6.8 6.6 6.3 6.1 5.9 5.8 5.5 5.4 5.2 This gives an idea of the error that can be introduced at different altitudes and allows you to calculate the quantity to be subtracted to correct your reading. 8 9 SALINITY COMPENSATION The table below shows the influence of salt in the measurement of oxygen. In HI 9142 all the readouts are referred to 0 g/l of salinity value. In fact, salinity affects D.O. concentration decreasing its value. For your reference the table below reports the oxygen solubility at various temperatures and salinity. From the table you can calculate the quantity to be subtracted to correct your reading. PROBE & MEMBRANE MAINTENANCE The oxygen probe body is made of reinforced plastic for maximum durability. A thermistor temperature sensor provides temperature measurements of the sample tested. It is always recommended that the protective cap be kept on the probe when the probe is not in use to provide protection against damage and dirt. To replace the membrane or refill with electrolyte, proceed as follows: · Remove the protective cap by gently twisting and pulling it off the body of the probe (see fig. 1). Unscrew the membrane by turning it counterclock-wise with the other hand (see fig. 2) Wet the sensor by soaking the bottom 2½ cm (1") of the probe in electrolyte (HI 7041S) for 5 minutes. Rinse the new membrane (HI 76407A) supplied with the meter with electrolyte while shaking it gently. Refill with clean electrolyte. Gently tap the sides of the membrane with your finger tip to ensure that no air bubbles remain trapped. Do no directly tap the bottom with your finger as this will damage the membrane. Salinity (g/l) at Sea Level °C 10 12 14 16 18 20 22 24 26 28 0 g/l 10 g/l 20 g/l 30 g/l 35 g/l °F 50.0 53.6 57.2 60.8 64.4 68.0 71.6 75.2 78.8 82.4 · 11.3 10.6 10.8 10.1 10.3 9.7 9.9 9.3 9.5 8.9 9.1 8.5 8.7 8.2 8.4 7.9 8.1 7.6 7.8 7.4 9.9 9.5 9.1 8.7 8.4 8.0 7.8 7.5 7.2 7.0 9.3 8.9 8.6 8.2 7.9 7.6 7.3 7.1 6.8 6.6 9.0 8.6 8.3 8.0 7.6 7.4 7.1 6.9 6.6 6.4 TWIST AND PULL fig. 1 · · · UNSCREW fig. 2 10 11 · · Make sure that the rubber O-ring is seated properly inside the membrane cap. With the sensor facing down, screw the membrane cap clock-wise. Some electrolyte will overflow. BATTERY REPLACEMENT When the battery is rundown "V" is displayed on the Liquid Crystal Display to warn the user. V The Platinum cathode (#8 in the Functional Description at page 4) should always be bright and untarnished. If it is tarnished or stained, which could be due to contact with certain gases or extended use with a loose or damaged membrane, the cathode should be cleaned. You can use a clean lint-free cardboard or cloth. Rub the cathode very gently side to side 4-5 times. This will be enough to polish and remove any stains without damaging the platinum tip. Afterwards, rinse the probe with deionized or distilled w ...