BOD-System OxiDirect. Instruction Manual

Transcription

1 BOD-System OxiDirect Instruction Manual GB

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3 Content 1. The system Principle of operation Applications Illustrations/Equipment supplied The method Biochemical oxygen demand (BOD) BOD sensors Principle of measurement BOD measurement Sample volume Preparing the water sample Preparing the sample / brief summary Operation Buttons Notes Technical terms Displays Setting up the unit Switching on Switching off Reading out measurement values Starting measurement Parameter menu Setting date and time Autostart Replacing batteries Interpreting the results Checking the measurement system Replacing the batteries Care and maintenance

4 Content 9. Inductive stirring system User instructions Correct use Instruction symbols Safety considerations Equipment description and function Start-up procedure Magnetic stirring rods Stirring Maintenance and cleaning Problems during operation The magnetic stirring rod rotates unevenly The stirring rod swerves back and forth Technical data BOD system Inductive stirring system Accessories and spare parts list

5 1. The System 1.1 Principle of operation BOD is determined by measuring the pressure difference within a closed system (respirometric BOD). The integrated memory saves a BOD value automatically every 24 hours for a test period of more than 2 days. For a period of 1 day a value is saved every hour, for 1 to 2 days, every 2 hours. 1.2 Applications Determination of BOD 5 and BOD 7, OECD 301F / biological degradability. Other bio-technological applications. 1.3 Illustrations / Equipment supplied 1 x BOD measuring device with integral bottle rack 6 x BOD sensor 6 x BOD bottles 6 x seal cups (Gasket) 6 x magnetic stirring rods 1 x stirring system drive 1 x stirring system controller 1 x nitrification inhibitor (ATH) 1 x potassium hydroxide solution (KOH solution, 45%) 2 x overflow measurement flasks (157 ml and 428 ml) 1 x instruction manual 5

6 2. The Method 2.1 Biochemical Oxygen Demand (BOD) The biochemical oxygen demand (BOD) of waste water, industrial effluents and surface water is an expression for the amount of oxygen consumed by the decomposition of organic matter in a biochemical process. BOD measurement is an important analytical tool in determining the effects of effluents on water treatment plants and surface water systems. 2.2 BOD Sensors The OxiDirect is a respirometric BOD measurement system, where BOD is determined in the bottle itself, without prior dilution. This method offers a range of advantages, compared with the so-called dilution method. The sample can be tested undiluted form; the measurement range is wider; the amount of work involved is significantly less. 2.3 Principle of Measurement The BOD measurement unit, consisting of the sample bottle and the BOD sensor, represents a closed system. In the bottle, above the sample itself, is a defined air space. During the BOD measurement the bacteria in the sample consume the dissolved oxygen in the sample. This is replaced by oxygen out of the air within the bottle, above the sample. The carbon dioxide released at the same time is chemically bounded by the potassium hydroxide in the seal gasket. This generates a decrease of pressure within the system. This is measured by the BOD sensor and displayed as a BOD value in mg/l O 2. 6

7 3. BOD Measurement 3.1 Sample Volume The sample volume is related to the expected BOD value. The OxiDirect is designed to operate over the measurement ranges and sample volumes shown in the following table, allowing for BOD measurement ranges of mg/l, without any dilution of the sample. Range BOD mg/l Sample volume in ml Drops ATH Table 1 Note The expected results should be in the upper half of the range. For example, if the expected BOD value is 250 mg/l, select a measurement range of mg/l and, therefore, a sample volume of 157 ml, for best results. For domestic waste it is generally safe to consider a BOD 5 value which is approximately 80 % of the COD value. 7

8 3.2 Preparing the Water Sample 1. Check the ph value of the effluent sample. The optimum ph value for biochemical oxidation is between ph 6.5 and 7.5. If the ph value of the sample is higher or lower, it should be pre-adjusted. Any significant deviation will result in a lower BOD value. If the ph value is too high, it can be reduced by adding dilute hydrochloric acid (1 mol/l) or dilute sulphuric acid (1 mol/l). If the ph value is low, it can be adjusted with a sodium hydroxide solution (1 mol/l). 2. Mix the water sample well and allow to settle for a short while. It may also be advisable to filter or homogenise the sample. Depending on the nature of the effluent to be examined (e.g., paper mill effluents, surface water, dairy wastes) the sample will need to be pre-treated. Samples containing fibres should be homogenised; samples containing algae should be filtered. BOD measurements will not be comparable unless the same pre-treatment is used. In the event of different results, the pre-treatment should be checked. 3. Measure out precisely the sample volume required, using the appropriate overflow measurement flask and pour the sample into the sample bottle (it may be helpful to use a funnel for this). Ensure that the sample in the bottle contains a representative portion of any solids in suspension. It is recommended that each sample should be tested twice or three times. It is essential to measure the sample volumes very precisely; otherwise, significant measurement errors may occur. Where two samples are generally the same but have different amounts of suspended solids, different results may be expected. If the difference between results is significant, the measurements should be repeated. Note The OxiDirect measurement system is designed to operate with the sample volumes shown in Table 1 and the sample bottles supplied with the system (or as spare parts). Different volumes or wrong sample bottle will lead to false results. We therefore recommend strongly that you always measure the samples with the overflow measurement bottle supplied. You should also use a funnel to transfer the sample to the BOD bottle. 4. To inhibit nitrification, we recommend the addition of nitrification inhibitor B ( = Allyl Thiourea, or ATH). This is particularly important for the low measurement range of 0-40 mg/l (for example, when checking discharges from effluent treatment plants). The ideal volume of nitrification inhibitor B to be added will depend on the measurement range - see Table 1. Note Nitrifying bacteria also consume oxygen. This consumption can occur within the first 5 days and is more likely with samples with low BOD levels. As a general rule, the BOD measurement should not include the oxygen consumption caused by nitrifying bacteria and this can be inhibited by using nitrification inhibitor B. This inhibitor suppresses the activity of the bacteria by enzymatic inhibition, so that only the breakdown of organic substances in the sample will be measured as the BOD value. If it is desired to measure oxygen consumption resulting from nitrification (N-BOD), carry out measurements of samples both with and without the use of nitrification inhibitor and compare the results. The difference between the two BOD values will represent the oxygen demand of the nitrifying bacteria. 8

9 5. Add a clean magnetic stirring rod to each sample bottle and add 3-4 drops of 45% potassium hydroxide solution to the seal gasket (this will absorb the carbon dioxide). Then insert the seal gasket in the rack of the bottle. Important The sample must never come in contact with the potassium hydroxide solution. Never use grease or any other lubricants as an additional sealing agent, for the BOD sensors or for the seal gasket. Products of this kind may contain solvents which will attack the sensor, resulting in severe damage to the plastic housing and even to a failure of the sensor. The use of sealing greases and lubricants is not covered by our guarantee! 6. Before measurement begins, the prepared sample must be brought to the desired temperature (e.g. BOD 5, 20 C ). This can be achieved by placing the sample in a thermostatically controlled cabinet, while stirring the sample continuously with the inductive stirring system. The OxiDirect has an optional Auto-Start function, which enables it to start with samples at temperatures from 15 to 20 C. When this Auto-Start function is switched on, the system checks at specific intervals to detect whether there has been a fall in pressure in the BOD bottle and will not start the timer until a pressure drop is detected (the timer will start to run at latest 3 hours after the BOD sensor has been initiated, whether or not a fall in pressure has been noted). 7. Place the BOD sensors on the sample bottles and tighten carefully. This is extremely important the system must be completely air-tight. Then place the BOD bottle, with the sensor screwed in position, into the bottle rack. This can be done in the thermostatically controlled cabinet itself. Alternatively, because of the user-friendly design of the OxiDirect, you can remove the entire BOD unit, with its integral bottle rack, from the thermostatically controlled cabinet, while leaving the inductive stirring system in the cabinet. There is no need to disconnect the cabling. Once the BOD bottles have been placed in the rack, the system is positioned over the inductive stirring system so that the 4 adjustment screws engage in the associated recesses in the stirring system drive. 8. Start the measurement process (see Section 4). 9. Incubate the sample in accordance with the instruction (e.g. BOD 5 for 5 days at 20 C). 9

10 3.3 Preparing the Sample / Brief Summary Estimate the measurement range for the sample under test and select the volume of the sample (see Table 1). Carry out any essential pre-treatment of the sample (e.g., setting the ph value; filtering; etc.). Measure the volume of the sample precisely, using the overflow measurement flask and transfer it to the BOD bottle, with the aid of a funnel. If necessary, add nitrification inhibitor (see Table 1). Insert the magnetic stirring rod in the BOD bottle. Place 3-4 drops of KOH solution into the seal gasket. Then insert the gasket in the rack of the bottle. Screw the BOD sensors to the sample bottles. Place the sample bottles in the bottle rack. Start the measurement process (see Section 4). Incubate the sample in accordance with the instructions (e.g. BOD 5 for 5 days at 20 C) 10

11 4. Operation 4.1 Buttons ESC Start Read + Enter ESC - switch the unit on and off - quit sub-menus - shut down an application START - start measurements READ - read and display the current value (this is not saved!) + - select the next completed / available head - increase parameters - - go back one head - reduce parameters ENTER - confirm input - switch to next stage in a menu 4.2 Notes Flicker of the display is normal. To ensure correct measurements the measuring tasks got a higher priority than the routine serving the display. If bottles have been added to the rack while switched off, the unit must be switched on once for starting the measurement. If bottles have been removed permanently from the rack while the electronics were off, the unit should be switched on and off once, so that these places do not affect the life span of the batteries. The unit will switch itself off after approximately 45 seconds. To prolong battery life, the unit should always be switched off immediately, after the current task has been completed. For taking the required measurements the unit will work in the background mode, with only the centre minus in the upper display being illuminated. Once the measurement is completed, the unit will switch itself off again. The battery capacity is monitored continuously. If the batteries are closed to the end of their effective life, the display show Lo bat. At this point, the batteries should be replaced (see : Replacing Batteries ). Because a reliable evaluation of the battery level cannot take place until the unit has been switched on for approximately 15 seconds, the switch off sequence, during which OFF is displayed, may take a little longer if the unit is switched off very shortly after it has been switched on. 11

12 4.3 Technical Terms Rapid read-out mode Read-out mode Start mode Completed head Free head Background mode Operating condition, in which the OxiDirect displays the last measurement value which has been stored and the period of measurement of a head. Operating condition, in which all stored measurement values for an individual head can be displayed, together with the time of measurement. Operating condition, in which measurements can be started A head which has completed its series of measurements A heads, where the series of measurements has been completed and at least one values has been displayed in read-out mode (see : Reading Out Measurement Values ). The OxiDirect is carrying out measurements, or is waiting just before a measurement execution time. However, the display is switched off, except for the centre minus in the upper display. Before switching on the unit, wait until the background mode has finished and the display is completely blank. 12

13 4.4 Displays LoAd OxiDirect has not located Provided at least one head is a valid head available, check the contacts LEDs LED permanently lit LED flashes These display the position of the head, to which the values in the display apply Measurement completed Measurement not yet completed UFL Underflow the BOD is lower Check that the sample bottle than the allowed range is fully sealed against (meaning below 0) the measurement head Check tempering of the system OFL Overflow the BOD exceeds the upper limit of the chosen measurement range Lo bat End of battery life Replace batteries Measurement No valid preasure condition found for Check that the sample bottle value flashes a start during the Autostart time is fully sealed with the window measurement head Check tempering of the system F1 F2 No measurement value available yet No start value available yet, so no current figure can be calculated F120 A fault has occurred during Start Do not remove a bottle or change their places during the Start procedure 13

14 4.5 Setting up the Unit The batteries are not in place for shipment. If necessary, take all samples from the rack, turn the rack around and open the battery compartment. Place the three alkalimanganese Baby cells (C-Size) in the battery compartment, making sure of correct polarity. The unit should then be started automatically and will be in the Date-Time sub-menu (see Setting Date & Time ). If the unit does not switch on, or is not in this sub-menu, switch to the Date-Time sub-menu as described in the instructions. Set date and time and switch the unit off. Switch it on again and the unit will go into Rapid Read-Out mode. Then switch the unit off again. 4.6 Switching On Switch the unit on by pressing the ESC button. The OxiDirect will now be in Rapid Read-Out mode and will display the final value of the first completed measurement which it finds (the Position LED will illuminate to indicate the position). If no completed measurement is available, the Position LED will flash. The upper display will show the time span (e.g., 5d for BOD5, while the lower display will show the last value which has been stored. If the display shows F 1, there is no stored value jet available. If no value could be measured at the specified time, the display will show -F-. The + button is used to switch over to the position of the next completed measurement, while the - button is used to select any head required. Positions without a bottle in places cannot be selected. 4.7 Switching Off The unit is switched off by pressing the ESC button, if it is in the Rapid Read-Out mode. During the switch-off sequence, the upper display will show OFF followed by the centre minus. During this time, no bottles must be taken from or added to the rack. The switch-off sequence is finished when the display no longer shows OFF and the centre minus has also disappeared. Do not push the ESC button during this sequence. If you wish to switch the unit on again, it is essential to wait until at least two seconds after the display is completely off. If the unit is not in the Rapid Read-Out mode, it will be necessary to press the ESC a number of times in order to switch off. 14

15 4.8 Reading Out Measurement Values Set the unit to Rapid Read-Out mode, select the desired position and press the ENTER button. The unit will switch to Read-Out mode for the bottle you have selected. The upper display will show the time of the measurement, the lower display will show the corresponding stored measurement value. If the measurement period is one or two days (for BOD1 and BOD2) the time of the measurement will be shown in hours. If the measurement period is longer than 2 days (BOD 3, BOD 4...) the figure shown in the display will read in days. Time in hours is displayed in the form of hxx (for example, h48 for the last measurement value for BOD 2 ). Time in days is displayed as dxx (for example, d 5 for the last measurement value for BOD 5 ). 4.9 Starting Measurement Starting a new measurement will delete all stored data for the sensor! Press the START key. The unit will switch to Start mode. It will then seek the first free position. The lower display will show the measurement range which was used last time, while the upper display will show the necessary sample volume. Use the + and - key to change the position (the + key will select the next free position, while the - key can be used to select any position). Press ENTER. The + and - keys can now be used to select the measurement range. Confirm the range selected by pressing ENTER again. The unit will now display last used measurement time span. If this is not changed within 3 seconds (use the + and - keys) this previous measurement duration is automatically adopted and the measurement will start. Following a modification, this automatic start will no longer operate. The start procedure can be stopped by pressing the ESC key. If the unit does not find a free position, it will select some head. In this case, the display will show del. If you wish this head to be used, press the START key again. The unit then changes to the selection of the measurement range. Once a measurement has been started, the unit will indicates the next free position. Pressing the ESC key will cause the unit to quit the Start mode and return to the Rapid Read-Out mode. 15

16 4.10 Parameter Menu Press the ENTER key and keep it pressed. Switch the unit on. Once the lower display has flashed 3 decimal points for approximately 3 seconds, release the ENTER key. The unit is now in the Parameter menu and will initially display the Date-Time submenu. Use the + and - keys to switch between the Date-Time, the Autostart and the Replace Batteries sub-menu. Press the ENTER key to select the required sub-menu. Leave the Parameter menu by pressing the ESC key and return to the Rapid Read-Out mode Setting Date & Time Switch the unit to the Parameter menu and select the Date-Time sub-menu : Set date. The unit will display da and the current year setting. Press the ENTER key. The unit will now display da and the current date setting in the form of MM.TT (MM = month and TT = day). Press the ENTER key. The unit will display ti and the time in the form of hh.mm (hh = hours and mm = minutes). Press the ENTER key. The upper display of the unit will flash JJ and the lower display will show the year. Use the + and - keys to increase or decrease the figures and store by pressing the ENTER key. Using the same method, set the figures for the month (the display shows Mo ), the day (the display shows dd ), the hour (the display shows hh ), the tens of minutes (the display shows M ) and the single minutes (the display shows m ). Finally, press the ENTER key in order to execute. The unit will set its internal clock to these figures and, if there was no fault, the display will show is Set. Before finally confirming by pressing the ENTER key, you can go back by pressing the ESC key or quit the Date-Time menu. 16

17 Autostart The Autostart function can be switched on or off. The setting which is selected will apply to all the heads on the rack from now on. In particular, when the Autostart function is switched off, an automatic start will also take place immediately for those heads which had been initiated by the Autostart function when it was switched on, but for which the start condition had not yet been achieved. To change the setting go to the Parameter menu and select the sub-menu : Set Auto. The + key is then used, in the Autostart sub-menu, to switch on the Autostart function. With the function switched on, the unit will display On Auto and can be switched off with the key. Once the selection has been made, you may quit the sub-menu by pressing the ESC key. This causes the new setting to become effective Replacing Batteries In order to replace the batteries without missing an intermediate measurement, make sure the tool required to open the battery compartment is to hand, as well as the new batteries (3 alkali-manganese baby cells (C-Size)). Set the unit to the Parameter menu and select the Replace Batteries sub-menu Set bat. Activate the menu by pressing the ENTER key. The unit will display bat. Press the ENTER key again. The display will flash, showing bat chg. Wait until the display becomes dark - this may take up to 6 minutes. At this point the unit has switched off. The batteries must be replaced within the next 4 minutes : the unit should not be without battery power for more than one minute. Take all the samples from the rack, turn the rack around and open the battery compartment. As soon as the old batteries have been removed, the new batteries must be inserted, so that they are in place and able to power the unit within one minute. Then close the battery cover, replace all the samples and switch the unit on. Once the unit has reached the Rapid Read-Out mode, it can be switched off again. If the unit goes automatically into the Date-Time menu after the batteries have been replaced, this indicates that the power supply was interrupted for too long. It will then be necessary to reset the date. 17

18 5. Interpreting the Results Start 1. Day 2. Day 3. Day 4. Day 5. Day 1. The BOD value on any particular day must be higher than that measured on the previous day. 2. BOD values do not increase in a linear manner. The increase is always smaller than that of the previous day. 3. If the BOD results increase in a linear manner, the sample has a higher BOD value than expected when the sample was prepared. 4. If BOD results rise suddenly in the course of measurement, this may be the result of nitrification. 5. If BOD results fall suddenly in the course of measurement, this may indicate that there is an air leak in the system. The information given in the previous pages refers in all cases to normal samples (municipal wastes) and the normal behaviour of bacteria in the course of a BOD measurement. However, special events are always possible, depending on the relevant circumstances. For example, if there is a reading of zero after 5 days, this may mean that there is a leak in the system, or severe inhibition. In the case of industrial effluents, special circumstances will often occur. Effluents of this kind may contain toxic substances and these must be removed from the sample, or the sample must be diluted so that the measurement results are not too low. In addition, nutrients (nitrogen; phosphate) and trace elements such as iron must be present in sufficient concentrations; otherwise bacterial growth may be limited and artificially low BOD values may be recorded. Where problems of this kind occur in the course of measurement, each individual case must be considered and resolved on its own particular merits. For further information, please ask for our application reports. 18

19 6. Checking the Measurement System The following test systems are available for checking the OxiDirect measurement system: 1) Quick-test-equipment The Quick-test unit for BOD sensors is a test unit which enables a BOD sensor to be subjected to a defined vacuum. It can therefore be used to carry out a speedy and simple check on the correct operation of individual BOD sensors. 2) Calibration Set The calibration Set enables a check to be carried out on all the components of the OxiDirect. It consists of special reagent tablets, which generate a defined vacuum in the sealed BOD bottle. With the calibration Set, it is therefore possible to check the entire OxiDirect system for functionality and correct sealing. 7. Replacing the Batteries When the batteries are low, Lo bat will appear in the lower display. To change the batteries, loosen the two security screws and remove the cover to the battery compartment. Replace the old batteries with three new batteries (Type: Baby/C/LR14, Alkali-Manganese) according to the procedure given in chapter Operation --> Parameter-Menu --> Replacing Batteries. All calibration data remain secure while the batteries are being changed. 8. Care and Maintenance High-quality metal alloys are used for the contacts between the BOD sensors and the bottle rack. If necessary, the contacts may be cleaned carefully with a soft cloth. To compensate for any irregularities and to ensure optimum contact between the BOD sensor and the bottle rack, the BOD measurement system has 4 levelling screws on its base. If necessary, the BOD base unit (including the bottle rack) and the BOD sensors can be cleaned carefully with a soft cloth. All parts which come into contact with the sample (BOD bottles; seal cups; magnetic stirring rod) must be cleaned thoroughly after each measurement. The bottles must be emptied completely and washed several times in hot water. Where any cleaning agents, washing up liquids, etc., are used, the parts must be rinsed thoroughly! The residues of such agents can interfere with BOD measurements. 19

20 9. Inductive Stirring System Fig. 1: Inductive stirring drive with stirring controller Stirring place Stirring drive Stirring controller Plug out Control cable 20

21 9.1 User Instructions Correct use This inductive stirring system has been designed for stirring liquids in BOD bottles Instruction symbols The following instruction symbols are used in this operating manual: DANGER! This sign refers to dangerous voltages DANGER! This sign refers to hazardous situations. Risks to human life are indicated by the term LIFE HAZARD i * CAUTION! This sign indicates risks to equipment and machinery INFORMATION This sign indicates easier working practices Indicates an operating step Indicates alternatives 21

22 9.2 Safety Considerations For your own safety, you should observe the following safety warning signs. The safety warnings indicate a possible sources of danger. At the same time they contain information on how correct action can avert danger. You will always find warning signs attached to points of possible danger. DANGER! Magnetism. Magnetic or metallic parts (e.g. data carriers, pacemakers, watches...) can be affected by magnetic fields. Keep such parts away from the magnetic stirrer (2) and the magnetic stirring rods DANGER! Supply voltage and supply frequency must be within the range specified for the control unit (3) CAUTION! Do not use in hazardous locations CAUTION! General ambient conditions : Stirring drive (2): -10 to +56 C at 100% humidity. Control unit (3): 0 to +40 C at max. 80% humidity. Avoid extreme temperature changes. The control unit (3) must not be run in humid rooms, or set up in areas where water may splash! 22

23 i CAUTION! Do not place hot stirring vessels on top of the magnetic stirrer (2). Maximum temperature : 56 C. CAUTION! In case of repair, the equipment must only be opened by an authorised service agent. Disconnect from mains before opening! CAUTION! Do not allow the magnetic stirring rod to come to rest in an alternating magnetic field (e.g. in an unfilled stirring vessel when the stirring or mixing mode is selected). Do not subject the magnetic stirring rod to a strong inverse magnetic field or to strong impact shocks (e.g. by dropping it). This may result in destruction of the magnetic stirring rod. INFORMATION The length of the magnetic stirring rod must not exceed 40 mm. Do not use elliptical stirring rods with a round cross-section. 23

24 9.3 Equipment Description and Function The stirring system has been designed for stirring liquids in standard BOD bottles. It consists of an ultra-slim stirring drive (2) with 6 stirring points (1) and a separate stirring controller (3). All the bottles can be removed from the rack without disturbing the stirring drive (2). Several stirring drives (2) can be installed next to each other, saving space. The stirring drive has no motor and is therefore wear-free. It is particularly suited to continuous stirring in a incubator. It is hermetically sealed (fully protected from splashing water) and can be used even in the roughest environments. The wide space between the stirring points (1) ensures good ventilation of the stirring containers, even in a incubator. The stirring drive (2) is controlled by a controller (3) with a pre-set speed. When turned on, the soft start feature ensures a uniform start of the magnetic stirring rods at half speed. Every 40 seconds, the electronically controlled automatic monitor reduces the stirring speed by 50%, re-centring the magnetic stirring rod in the middle of the bottle for several seconds. This means that individual bottles may be hot-swapped or the rack installed during operation. The magnetic stirring rods are operated synchronously, preventing practically any interference between them. 9.4 Start-up procedure DANGER! Supply voltage and supply frequency must be within the range specified for the control unit (3) * DANGER! Magnetism. Magnetic or metallic parts (e.g. data carriers, pacemakers, watches...) can be affected by magnetic fields. Keep such parts away from the magnetic stirrer (2) and the magnetic stirring rods. CAUTION! Do not use in hazardous locations CAUTION! General ambient conditions: Stirring drive (2): -10 to +56 C at 100% humidity. Control unit (3): 0 to +40 C at max. 80% humidity. Avoid extreme temperature changes. The control unit (3) must not be run in humid rooms, or set up in areas where water may splash! The control unit (3) does not have an on-off switch. It is ready for use as soon as it is plugged in. Connect the control cable (5) from the stirring drive (2) to the output socket (4) of the control unit (3) while tightening the thumb-wheel. Plug the control unit (3) into the mains socket. 24

25 9.5 Magnetic stirring rods We recommend the use of PTFE-coated magnetic stirring rods. i INFORMATION The length of the magnetic stirring rod (8) must not exceed 40 mm. 9.6 Stirring * CAUTION! Do not place hot stirring vessels on top of the magnetic stirrer (2). Maximum temperature : 56 C. Fill the bottles with the sample. Place a magnetic stirring rod into every bottle. Place bottles in the BOD rack. The control unit (3) is preset to operate at 320 rpm. The electronically controlled automatic monitor reduces the stirring speed to about 200 rpm, re-centring each magnetic stirring bar in the middle of the bottle for several seconds. This means that individual bottles may be hot-swapped or the rack installed during operation. * If you want to stop the stirring process: Disconnect the control unit (3) from the mains socket. 25

26 9.7 Maintenance and Cleaning The stirring drive (2) is maintenance-free. The magnetic drive inside the housing is embedded in synthetic resin and is completely watertight. Clean the surface of the stirring drive (2) at regular intervals. It may be cleaned under running water. Alternatively, you may clean the stirring drive (2) with a disinfectant solution suitable for use on PVC. Wipe the surface of the stirring controller (3) using a damp cloth. CAUTION! In case of repair, the equipment must only be opened by an authorised service agent. Disconnect from mains before opening! 9.8 Problems during Operation The magnetic stirring rod rotates unevenly: Some ageing of the stirring rod in time cannot be avoided. This may reduce its magnetisation. * CAUTION! Do not allow the magnetic stirring rod to come to rest in an alternating magnetic field (e.g. in an unfilled stirring vessel when the stirring or mixing mode is selected). Do not subject the magnetic stirring rod to a strong inverse magnetic field or to strong impact shocks (e.g. by dropping it). This may result in destruction of the magnetic stirring rod. Replace it by a new one The stirring rod swerves back and forth: * Swerving movements of the magnetic stirring rod may be caused by irregularly shaped forms of the bottle. This may occur, for instance, in the case of BOD bottles with a convex bottom if the bottom is shaped irregularly or asymmetrically. Replace the bottle by a new one. 26

27 10. Technical Data 10.1 BOD System Type OxiDirect Measurement principle Ranges [mg/l O 2 ] Manometric; mercury-free; electronic pressure sensor 0-40, 0-80, 0-200, 0-400, 0-800, , mg/l Applications BSB 5, BSB 7, OECD 301 F... Result display Measurement parameter display Measurement period Auto result storage Storage intervall Automatic start function Power supply Battery life Clock Protection class BSB [mg/l]; 4 - digits; 7 - segment LED BOD-range, volume, duration, display time of measurement User-selectable, between 1 and 28 days up to 28 results, depending on measurement period hourly (1 day); every 2 hours (2 days); daily (3-28 days) After temperature equalisation of samples can be switched off 3 alkaline-manganese batteries 1 year (normal use as BOD 5 meter max. one reading a day); early warning before battery fails Real-time clock IP54 (sensor head) Dimensions 375 x 195 x 230 mm (L x W x H) included stirring unit Housing Approval ABS CE 27

28 10.2 Inductive Stirring System Type Stirring volume Stirring power Rotation speed Dimensions (W x D x H) Distance between stirring points Weight (stirring drive) Housing material General Ambient Conditions Operating voltage Control cable Inductive Stirring System 6 BOD bottles 7 W 320 rpm (briefly reduced to 200 rpm every 40 s) 270 x 180 x 25 mm 88 mm 1800 g PVC -10 to +56 C at 100 % humidity 20 V max. 2 m Protective system IP 68 (DIN 40050) Stirring controller 230 V version V / 10 V / Hz, protection class II, Thermosicherung, CE-Zeichen 115 V version V / 10 V / Hz, protection class II, thermal feature Permanent ambient conditions 0 to + 40 C at max. 80 % humidity Protection class IP 20 (DIN 40050) 28

29 11. Accessories and Spare Parts List Article Order code Replacement BOD sensor Replacement BOD base unit Stirring controller Inductive stirring drive Quick-test-equipment Calibration Set Potassium hydroxide solution (50 ml) Nitrification inhibitor B (50 ml) BOD sample bottle Seal cup (gasket) Diagram pad Magnetic stirring rod Magnetic stirring rod remover Overflow measuring flask, 428 ml Overflow measuring flask, 360 ml Overflow measuring flask, 244 ml Overflow measuring flask, 157 ml Overflow measuring flask, 94 ml Overflow measuring flask, 56 ml Overflow measuring flask, 21, 7 ml Thermostatically controlled incubators Thermostatically controlled incubators with glass door see general catalogue see general catalogue 29

30 Technische Änderungen vorbehalten. Printed in Germany 09/03 We reserve the right to alter or amend any of the items contained herein without prior notice. AQUALYTIC P.O. Box Dortmund Germany Telefon: (+49) (0)2 31/ Telefax: (+49) (0)2 31/