442 ph/conductivity Meter

Transcription

1 442 ph/conductivity Meter Instruction Manual This manual contains complete instructions for setting up and using the 442 ph/conductivity meter. Applications information is also available. The information contained in this manual was correct at the time of going to print. However, we continue to improve products and reserve the right to change specifications, equipment and maintenance procedures at any time. This manual is copyrighted, and all rights are reserved. No part of this manual may be reproduced by any means or in any form without prior consent in writing. The power supply unit is classed as IEC Class II equipment (equipment providing an adequate degree of protection against electric shocks, in which additional safety precautions, for example, double or reinforced insulation, are included). The 442 is intended for use by persons knowledgeable in safe laboratory practices. If the 442 is not used in accordance with these instructions, the protection provided by the equipment may be impaired. The 442 is suitable for direct current only. This equipment generates, uses and can radiate radio frequency energy and if not installed and used in accordance with the instruction manual, may cause interference with radio communications. It has been tested and found to comply with the limits for a Class A computing device pursuant to Subpart J of Part 15 of FCC Rules, which are designed to provide reasonable protection against such interference when operated in a commercial environment. Operation of this equipment in a residential area is likely to cause interference in which case the user at his own expense will be required to take whatever measures may be required to correct the interference. There are no user replaceable parts in the 442 or power supply unit. Do not remove the covers Rev. A, 9/97 1

2 Contents 1 Set Up 1.1 Unpacking and Installation Input and Output Connections Display and Controls Operation 2.1 Calibrating Measuring Samples mv Measurements Buffer Temperature Correction Table for ph Automatic Endpoint (Auto Read) Memory Continuous Data Transfer Interfacing via the RS232 Output Chart Recorder Meter Programming 3.1 Meter Programming in ph/mv Meter Programming in Conductivity/TDS Support Information 4.1 Basic Theory Operating Hints Maintenance Problem Solving Meter Specifications Consumables and Accessories... inside rear cover Warranty... inside rear cover Rev. A, 9/97

3 1.1 Unpacking and Installation 1. The main carton will contain the following: Meter with a shorting (test) clip in the ph socket Meter Dust Cover Power Supply This Instruction Manual Memo Cards, English, French, German, Italian, Spanish Warranty Card Calibration Certificate 1 2. If you ordered any accessories, refer to the accessories packing sheet for a list of the additional components. 3. To attach the sensor or electrode arm to the meter: a. The sensor or electrode arm can be attached to the left or right-hand side. Using the screwdriver supplied remove the appropriate end cap from the meter. b. Slide the arm base into the recess and tighten the fixing screw. Replace the end cap. c. Fit the sensor arm onto the post. Adjust the tension screw as required. sensor arm arm base end cap fixing screw tension screw screwdriver 4. Fill in and return the warranty card. For your own record make a note of the serial number, date of purchase and supplier on the inside front cover of this manual Rev. A, 9/97 3

4 1.2 Input and Output Connections 1 DC - power supply unit socket REC - ph recorder output socket for use with glass electrode, see Section 2.9 for details REF - reference electrode socket SENSOR - conductivity sensor socket DATA - data output socket, see Section 2.8 for interfacing details ATC - ATC (automatic temperature compensation) probe socket ph - combination or ph electrode socket 1. Disconnect the shorting clip from the ph socket and retain it by clipping it over the socket. 2. Connect the electrode to the ph socket. 3. If you are using a separate ATC probe for the ph channel connect it to the ATC socket. 4. Connect the conductivity sensor, which has a built-in temperature sensor, to the SENSOR socket. 5. Connect the power supply unit to the DC socket. 1.3 Display and Controls Controls for Conductivity/TDS Controls for ph/mv Rev. A, 9/97

5 1.3 Display and Controls (cont) on/off Places meter into standby mode/wakes meter up for both ph/mv and Conductivity/TDS Controls for ph/mv mode Selects ph or mv mode and deselects channel. Hold down for 2 seconds to enter Program menu. 1 < M Stores result in memory. Increases value in Program menu. Hold down for 2 seconds to turn beeper on/off. <R Recalls result from memory. Decreases value in Program menu. Hold down for 2 seconds to turn continuous data transfer on/off. auto Turns auto endpoint on/off. cal Starts calibration. Hold down for 2 seconds to recall calibration data. Starts/stops measurement. Hold down for 2 seconds to reset sample ID number. 442 Display - ph/mv stability/auto endpoint indicator main display date and time icon electrode condition indicator program menu and data transfer icons automatic or manual temperature compensation indicator temperature, electrode offset/slope memory, cal and error number Rev. A, 9/97 5

6 1.3.2 Controls for Conductivity/TDS 1 mode < M <R Selects conductivity or TDS mode and deselects channel. Hold down for 2 seconds to enter Program menu. Stores result in memory. Increases value in Program menu. Recalls result from memory. Decreases value in Program menu. Hold down for 2 seconds to turn continuous data transfer on/off. auto Turns auto endpoint on/off. cal Starts calibration. Starts/stops measurement. 442 Display - Conductivity/TDS stability/auto endpoint indicator main display continuous data transfer icon automatic or manual temperature compensation indicator temperature, electrode offset/slope memory, cal and error number Rev. A, 9/97

7 2.1 Calibrating Calibrating a ph Electrode 1-point calibration We recommend that your first calibration should be carried out using 7.00 ph buffer, but you may use other buffers for this. Place the tip of the electrode in the calibration buffer and press cal To move straight to another buffer press cal again until the appropriate buffer is displayed. Continued pressing of cal will return you to the measurement screen. If you have the 'auto ' feature (see Section 2.5) turned on, the meter will automatically endpoint when the ing is stable and the appropriate buffer symbol will appear on the display. If you don't have 'auto ' on, press to freeze the ing when the stability indicator appears. Rinse the tip of the electrode with distilled or deionized water and go to Measuring ph/mv Samples (Section 2.2.1) or 2 point calibration. NOTE If you are using an ATC probe (or an electrode incorporating ATC), temperature is being measured and the buffer value is being corrected for temperature (see Section 2.4). If you are not using an ATC in the system, the Model 442 assumes a temperature of 25 C. 2 2-(3-)point calibration Place the tip of the electrode in the second buffer and press cal If you have the 'auto ' feature (see Section 2.5) turned on, the meter will automatically endpoint when the ing is stable and the appropriate buffer symbol will appear on the display. If you don't have 'auto ' on, press to freeze the ing when the stability indicator appears. Rinse the tip of the electrode with distilled or deionized water and go to Measuring ph/mv Samples (Section 2.2.1) Rev. A, 9/97 7

8 2.1 Calibrating a ph Electrode (cont) NOTE For maximum accuracy, we recommend using an ATC probe or the 3-in-1 Combination electrode which includes an ATC probe. If you do not have an ATC probe you should make sure that all buffers and samples are at 25 C Calibrating a Conductivity Sensor Press mode to select conductivity or TDS mode. 1-point calibration Hold the sensor in air and press cal. To move straight to a cal 2 calibration press cal again. 2 If you have the 'auto ' feature (see Section 2.5) turned on, the meter will automatically endpoint when the ing is stable. If you don't have 'auto ' on, press indicator appears. when the stability 2-point calibration Place the tip of the sensor in the conductivity standard and press cal. If you have the 'auto ' feature (see Section 2.5) turned on, the meter will automatically endpoint when the ing is stable. If you don't have 'auto ' turned on, press stability indicator appears. when the Rinse the sensor with distilled or deionized water and go to Measuring Conductivity/TDS Samples (Section 2.2.2). NOTE For maximum accuracy, samples and standards should be at the same temperature, preferably the reference temperature (see Section 3.2.2) Rev. A, 9/97

9 2.2 Measuring Samples NOTE Good laboratory practice dictates that electrodes and sensors should be calibrated at least daily Measuring ph/mv Samples Place the tip of the electrode in the sample and press start the measurement. The decimal point will be flashing whenever the sensor is ing. to If you are using the 'auto ' function the display freezes when a stable endpoint is reached (see Section 2.5). If you are using manual endpoint the stability indicator appears when the electrode output has stabilized. To freeze the display press Measuring Conductivity/TDS Samples Place the sensor in the sample and press measurement. to start the Ensure that the solids factor and temperature coefficient set are appropriate for the sample being measured. The decimal point will be flashing whenever the sensor is ing. If you are using the 'auto ' function the display freezes when a stable endpoint is reached (see Section 2.5). 2 If you are using manual endpoint the stability indicator appears when the electrode output has stabilized. To freeze the display press Temperature Measurement While you are carrying out normal calibration or measurement, the instrument will display temperature on the secondary display Rev. A, 9/97 9

10 2.3 mv Measurements The millivolt capability of ph meters can be used to determine the actual slope of ph electrodes but is most frequently used for doing potentiometric ings or titrations with Platinum Oxidation-Reduction electrodes. Press mode until mv shows at the top of the display. Put the tip of the electrode in the sample and press The meter will display absolute millivolts. When the ing is stable, press to freeze the display. 2.4 Buffer Temperature Correction Table for ph 2 The 442 automatically corrects for temperature using the values shown in the table C C C C C C C C C C Rev. A, 9/97

11 2.5 Automatic Endpoint (Auto Read) The 'auto ' function checks the sensor output for stability and automatically freezes the display when the ing appears stable. It can be used during calibration and routine measurements in ph, mv, Conductivity and TDS modes. Turn auto endpoint on by pressing auto The auto endpoint indicator A will appear at the top left of the meter display. While the meter is ing, the decimal will flash. When the endpoint is reached, it will stop flashing and the stable endpoint indicator will appear. To start another ing press To cancel auto endpoint press 2.6 Memory auto again Up to 10 endpointed results can be stored for ph/mv and 10 for Conductivity/TDS. 2 Before a result can be stored it must have reached a stable endpoint, using either manual or auto endpoint. To store a result in memory: press the result is stored and the display shows M 1 < M (or M 2 to M 10 if ings have aly been stored). M 10 indicates the memory is full Rev. A, 9/97 11

12 2.6 Memory (cont) Before a result can be recalled from memory the current measurement must have reached a stable endpoint. To recall a result from memory: press<r to recall the last stored memory. Press <R to scroll through the memories. The display shows RM and the appropriate memory number. M 0 indicates no memories have been stored. To clear all memories: 2 press until MC is displayed, then press to clear the <R M memories. (Press to exit without clearing the memories.) 2.7 Continuous Data Transfer < In continuous data transfer mode ings are sent to the DATA socket approximately every second. If the measurement endpoints (manually, or using auto ) data transfer stops. If you recall memories all stored ings are output (from the first to the last stored). To select continuous data transfer mode: press and hold indicator appears <R for 2 seconds. The continuous data transfer To maintain continuity of sample ings calibration data is only output at endpoint. To send data from only one channel, deselect the channel not required by pressing mode Rev. A, 9/97

13 2.8 Interfacing via the RS232 Output The Model 442 can transmit data in RS232C Serial format to compatible devices such as Serial Printers and computers. The cable required for connection to IBM compatible computers is part number and can be ordered from your distributor. The pin configuration of that connector and Model 442 output protocols are as follows: Pin Signal 1 device enable (link to pin 5) 2 RS232 Tx (signal transmit) 3 not used 4 CTS (clear to send) 5 protective ground (0V) 6-9 not used protective ground (0V) DATA socket CTS signal transmit 2 To enable the RS232 a link is required between pin 1 (device enable) and pin 5 (protective ground). Type of communication - unidirectional Baud rate Data format - 8 data bits 1 stop bit no parity Data is sent to the DATA socket at measurement endpoint (manual or automatic), calibration recall and memory recall. To use the output to monitor continually, you need to select continuous data transfer mode (see Section 2.7) Rev. A, 9/97 13

14 2.9 Chart Recorder This is available in ph/mv mode only 0V data output REC Socket The REC socket provides a voltage proportional to the displayed ing in ph and mv modes. The polarity of the output is the same as the polarity of the input signal. Approximate Recorder Outputs 2 ph - Output follows display and provides approximately 30 mv output per ph unit. This value will vary with changes in electrode slope and temperature. mv - Output follows display, i.e. as display varies from 1999 to 1999 mv, output varies from 999 to +999 mv. The recorder output is not available in temperature or conductivity mode Rev. A, 9/97

15 3.1 Meter Programming in ph/mv The Program Menu allows you to set manual temperature compensation, ph calibration buffers, calibration reminder and date and time. You can only enter the Program Menu if the current measurement has endpointed - press if necessary. Press and hold the mode key for 2 seconds to access the Program Menu - appears. Press mode to scroll through the options and press and M < to change the value. Press to exit the Program Menu at <R any time. If you press will not be entered. when a value is flashing that value Calibration Reminder The calibration reminder interval can be set, in hours, between 0 and 99 (where 0 = no reminder). When the selected time has elapsed the calibration reminder symbol will appear. The 442 has a preset reminder interval of 1 hour. Change the interval using and. Press mode to enter M <R the value and move on. < Time and Date Time and date are displayed during calibration recall, and will be sent to the serial output. Time is shown on the main display, the date is shown on the lower part of the display. Set the time and date using and. M <R Press mode to enter the value and move on. < Rev. A, 9/97 15

16 3.1.3 Manual Temperature Compensation MTC You can enter temperature manually between -5.0 and C. (An ATC probe will override manual compensation.) The meters have a preset temperature of 25 C. Use and to change temperature. M <R < Press mode to enter the value and move on ph Buffer Selection The buffers are grouped in sets (b = 1, b = 2, b = 3); select your required set first using and M <R : set 1 = 7.00, 4.00, 10.01, 1.68 set 2 = 7.00, 4.01, 9.21, 2.00, set 3 = 6.87, 4.01, 9.18, 1.68 Press mode to enter the set and move on. < NOTE: Check buffer set 1 is selected to use the buffers supplied. Choose three buffers (cal 1, cal 2, cal 3) from the set for calibration. For ease of use, set the buffers in the order cal 1 cal 2 that you will use them. cal 3 For example: Set 1 (factory settings) cal 1 = 7.00, cal 2 = 4.00, cal 3 = (1.68 not selected). 3 These can be arranged in any order using and. M <R Press mode to enter the value and move on. Press to exit the Program Menu. < Rev. A, 9/97

17 3.2 Meter Programming in Conductivity/TDS The Program Menu allows you to set solids factor, reference temperature, temperature coefficient and TDS units. You can only enter the Program Menu if the current measurement has endpointed - press if necessary. Press and hold the mode key for 2 seconds to access the Program Menu - appears. Press mode to scroll through the options and press and M < to change the value. Press to exit the Program Menu at <R any time. If you press will not be entered Solids Factor when a value is flashing that value P1 The solids factor is the ratio of TDS (ppm or mg/l) to conductivity (µs/cm) and can be set between 0.40 and The 442 has a preset solids factor of Change the value using and. Press mode to enter the M <R value and move on. < Reference Temperature P2 The temperature to which measurements are referenced can be set to 20 or 25 C. The 442 has a preset reference temperature of 25 C. Change the temperature using and. Press mode to enter the value and M <R move on. < Rev. A, 9/97 17

18 3.2.3 Temperature Coefficient P3 Conductivity measurements change with temperature. The temperature coefficient (%/ C) is a measure of this change and can be set between 0.0 and 10.0, as appropriate for the sample being measured. Adjusting the temperature coefficient affects the instrument temperature range (see section 4.5). The 442 has a preset temperature coefficient of 2.0 C. Change the coefficient using and. M <R Press mode to enter the value and move on. < TDS Units P4 TDS can be measured in mg/l or ppm. (The 442 auto ranges to g/l or ppt). Change the units using <. Press mode to enter the units and move on. <R M and Press to exit the Program Menu Rev. A, 9/97

19 4.1 Basic Theory Basic Theory of ph/mv ph is the unit of measurement of the acidity or alkalinity of a solution, and is expressed as the negative logarithm of the hydrogen ion concentration: ph = log[h + ] 4 ph 0 is very acidic, ph 14 is very alkaline and ph 7 is neutral. For routine ph measurements a sensing electrode and a reference electrode or a combination electrode (both electrodes in one body) are used along with a meter capable of displaying the measurements. The ph sensing electrode has an internal solution with a constant ph value, and develops a potential when placed in a solution. This is caused by the activity of the H + ions in the solution. The reference electrode has a defined, stable potential irrespective of the H + activity in the sample. The Model 442 measures and converts the resulting minute electrode voltages into a ph ing. The response of a ph electrode (or its slope ) is defined by the Nernst equation: Electrode response = E 0 2.3RT. ph nf where: E 0 = a constant factor R = the gas constant F = the Faraday constant T = the temperature in Kelvin n = the ionic charge The theoretical slope for an electrode is mv where the H + ionic charge (n) = 1 at 25 C (298K). This means that for a one unit change in ph the system will sense a change of mv. The measurement of electrode slope is a good indication of electrode condition Rev. A, 9/97 19

20 4.1.1 Basic Theory of ph/mv (cont) 4 Temperature is also an important consideration when measuring ph. It affects the electrode slope. ATC probes are recommended so that the slope can be corrected for temperature. There are many other factors that affect ph. Further information on ph theory and the factors that affect the ability to do accurate ph ings is included in Guide to ph Measurement Basic Theory of Conductivity/TDS Conductivity is the ability of a solution to pass current. It follows that the amount of current flowing is proportional to the number of ions present in the conducting solution. Therefore, a measure of the conductivity will give a direct ing of the solution concentration. All substances conduct to some extent. In solution the level of ionic strength varies from the low conductivity of ultra pure water to the high conductivity of concentrated chemical samples. Historically, the measurement of conductivity was made between two platinum plates (1cm x 1cm in size) placed one centimetre apart. This method simplifies the theoretical interpretation of results. However, in practice it results in a plating effect when current flows, and reduces the conductivity electrode performance. Because conductivity values are affected by cell geometry, specific conductivity (C) should be used. This compensates for cell geometry and standardises conductivity measurements. If the cell is filled with a solution of conductance, G, the conductivity between the electrodes is given by the expression C = G.L A where: C = conductivity in Siemens per cm (S/cm) G = conductance in Siemens (S) L = distance between electrodes (cm) A = plate area of the electrodes (cm 2 ) Rev. A, 9/97

21 4.1.2 Basic Theory of Conductivity/TDS (cont) As the cell dimensions change, the cell constant varies as the ratio of L to A. In the traditional cell using 1 cm squares of platinum, 1 cm apart, the cell constant (L/A) is 1.0 and the conductance ing in microsiemens is numerically equal to the conductivity in µs/cm. Sensors have been developed to overcome the problems associated with traditional cells. They operate on a four ring principle. An alternating voltage is applied to the two outer rings. In the sample solution, the voltage induces a current, whose magnitude is dependent upon the number of ions in solution. Therefore, the current measured by the inner sensing rings gives a direct value for the conductivity of the solution. By relating the conductivity of a standard solution to its concentration, a value for Total Dissolved Solids (TDS) can also be determined. Total Dissolved Solids (TDS) is a measurement of the total concentration of ionic species in a sample. The measurement of solution conductivity gives a method by which a TDS value for the sample solution can be determined. The 442 includes a user selectable TDS factor in order to give a TDS value referenced to a calibration standard (usually KCl or CaCO 3 ). The conductivity of a solution will increase with temperature. The effect is usually expressed by a change of conductivity (as a percentage) per degree Celsius. This is often called the temperature coefficient of the solution. For example, ultra pure water has a temperature coefficient of 5%/ C whereas that of concentrated samples may be at the 1%/ C level. The 442 has a user selectable temperature coefficient value for accurate ings. A temperature sensor is incorporated into the conductivity sensor supplied for use with the 442 to determine the exact solution temperature and to display a conductivity ing converted to a chosen reference temperature (usually 20 C or 25 C). For accurate measurements, samples and standards should be at a similar temperature, preferably at the chosen reference temperature Rev. A, 9/97 21

22 4.2 Operating Hints 4 This section gives some brief operating hints and good laboratory practices to help assure trouble free ph and conductivity measurements. For greater accuracy, standards and samples should be at the same temperature. Do not use calibration standards after the expiration date printed on the package. Keep the bottles tightly capped and stored according to the manufacturer's instructions. Never put used standards back into the bottle. Always measure ph and conductivity separately. Results will be affected if both are measured at one time in the same beaker Operating Hints for ph/mv Refer to the electrode manufacturer's instructions for proper electrode care and maintenance. See Section for general electrode maintenance and Section for problem solving. 1. New electrodes (or electrodes that have been in storage) should be conditioned in one inch (25mm) of ph 7.0 or 4.0 buffer for several hours prior to their use. Make sure that the wetting cap has been removed from the tip of the electrode. 2. Always remove the wetting cap and fill hole plug during calibration and measurements. Replace the fill hole plug when done. 3. Calibrate the electrode daily. Though a 1 point calibration may be suitable for some applications, we recommend that a 2 point calibration (that brackets the expected ph range) be performed. 4. Be aware that if you are measuring hot or cold samples without the use of an ATC probe, the values displayed are not accurate. You should be calibrating and measuring at room temperature Rev. A, 9/97

23 4.2.1 Operating Hints for ph/mv (cont) 5. When transferring from one sample to another, always rinse the electrode with distilled water and blot dry. Handle the electrode carefully and do not use it as a stirring rod. 6. For small sample volumes, make sure that both the ph bulb and the reference junction are in contact with the sample. 7. Response time is a function of both the electrode and the solution. Some solutions have very fast response while others, particularly those with low ionic strength, may take several minutes. 8. Samples must be in solution (water). You cannot measure the ph of a dry sample. 9. Correct storage of ph electrodes is very important. Consult the electrode manufacturer's instructions for advice on how to store the electrode Operating Hints for Conductivity/TDS Refer to the sensor manufacturer's instructions for proper sensor care and maintenance. See Section for Sensor maintenance and Section for Problem solving. 1. When measuring, make sure the solution is above the cell chamber slot. 2. Make sure the cell chamber is free of bubbles when measuring. To reduce air bubbles, stir centrally and then leave to stabilize. 3. Allow sufficient time for the sensor to stabilize when measuring samples of different temperatures. 4. Rinse sensor with next measurement sample between measurements, and ensure sensor is dried when re-zeroing the instrument. 5. For greater accuracy, calibrate using a standard close in value to the sample Rev. A, 9/97 23

24 4.3 Maintenance Meter Maintenance The Model 442 Meter needs no maintenance except for an occasional wipe with a damp cloth. The casework is made of ABS/PC which is known to be affected by some organic solvents, including toluene, xylene and methyl-ethyl-ketone. It is good laboratory practice to wipe away any spills as soon as they occur ph/mv Electrode Maintenance CAUTION Solutions used to clean electrodes must be handled with the care accorded to toxic or corrosive substances. Do not allow the reference chamber of the electrode to dry out. Always keep it filled with the proper fill solution. Formation of KCl salt at the tip and side of the electrode is normal and should be rinsed off with warm water. Leave the tip of the electrode in an inch (25mm) of ph 7.0 or 4.0 buffer when it is not being used. Do not leave it in distilled water. For long term storage follow the electrode manufacturer's instructions. If the electrode slope is off or the electrode response has become sluggish or inaccurate, change the fill solution. If that does not improve the response then the ph sensing glass and the junction have probably become coated with some of the samples being tested Rev. A, 9/97

25 Electrode Maintenance (cont) Test the junction for flow - rinse the tip of the electrode, blot dry and let the electrode hang in the air for 15 minutes. A proper flowing junction should have KCl salt crystals forming on it. If none appear, review the following suggestions for cleaning. Protein contamination - Soak the tip of the electrode for 1-2 hours in a solution of 10% Pepsin and water with enough Hydrochloric acid added to bring the ph of the solution to 1.0. Rinse the electrode and soak in ph 7.0 buffer until stable. 4 Oil contamination - Carefully clean the tip of the electrode using a cotton swab soaked with alcohol or acetone. The tip of glass body electrodes can be put directly into organic cleaners but do not put plastic or epoxy body electrodes into organic solvents. Rinse the electrode and soak in ph 7.0 buffer until stable. All others - Soak tip of the electrode in 0.1 M Hydrochloric acid for one hour. Rinse the electrode and soak in ph 7.0 buffer until stable. Refer to the electrode product insert for full details on maintaining your electrode Conductivity/TDS Sensor Maintenance CAUTION: To prevent static damage to the 442 avoid touching the cell chamber area of the sensor. ALWAYS disconnect the sensor from the 442 meter before cleaning. Solids build up inside the cell chamber can be carefully removed with a cotton wool bud soaked in detergent solution, then rinse the sensor with distilled water. Do not use organic solvents to clean the sensor Rev. A, 9/97 25

26 4.4 Problem Solving Problem Solving in ph/mv Most problems are caused by electrode faults rather than by the Model 442 but power fluctuations can corrupt calibration values being held in the meter memory Meter Test in ph/mv Disconnect the electrode from the meter and install the shorting clip in the electrode socket. If the meter is operating properly it will display a stable ph value between 6.98 and 7.02 (or 0 ± 1 mv in the millivolt mode). If the meter passes the above test the problem is electrode related. Refer to Section for electrode troubleshooting. If the meter fails the above test call the number on the back of this manual for warranty and service information Meter Error Codes for ph/mv Error codes are designed to give the user information on electrode performance problems. Err 1 - Electrode is not ing a value close enough to the first calibration buffer. Electrode needs maintenance. Err 2 - Slope out of range Slope less than 85%, or not calculable. Electrode needs cleaning, conditioning or replacing. Check correct buffers are used. Slope more than 105.0%. Check calibration buffers. NOTE: Where 0 mv/ph unit = 0%, and mv/ph unit = 100% (at 25 C) Err 3 - ph buffer outside temperature limits ph buffers must be between 5 C and 50 C for accurate calibration Rev. A, 9/97

27 Meter Error Codes for ph/mv (cont) Measurement is out of range of the display. The meter would display dashes if the electrode were not in a solution, the ph of the solution is not between 0.00 and or if the fill solution in the electrode is low or wrong. Dashes in the temperature mode indicates that the ATC has failed. Slope is a value that compares the actual slope determined by the calibration to the theoretical slope defined by the Nernst equation. This value is displayed as a percent of theoretical and is called electrode efficiency (see Section for basic theory). Generally the slope value can be interpreted as follows: % Everything is probably working fine % Electrode needs maintenance. Fresh fill solution and general cleaning % Stop and do full electrode maintenance now. Below 85 % Will not calibrate. Do full electrode maintenance or replace the electrode. Refer to the electrode manufacturer's instructions for full details on maintenance, cleaning and reconditioning electrodes. Although slope is useful in generally determining when it is time to do maintenance on an electrode, Response Time is, by far, the critical factor affecting accuracy of measurements. When moving from the 7.00 to the 4.00 buffer during calibration, you should have a stable value in seconds. Give a 7.00 to calibration seconds for a stable value. If it takes longer, the electrode response is getting slow and the calibration may not be accurate. Refer to the manufacturer's instructions for electrode maintenance Rev. A, 9/97 27

28 Electrode Problem Solving in ph/mv 4 Slow response or unstable ings in calibration buffers is usually related to the condition of the reference fill solution or its flow through the junction. 1. The fill solution acts as an electrical conductor between the reference inside the electrode and the solution under test. Empty the electrode and refill with fresh fill solution regularly. 2. The junction is designed to allow the fill solution to leak out of the tip of the electrode at a slow controlled rate. To test for proper flow, rinse the tip of the electrode, blot dry and let the electrode hang in the open air for 15 minutes. If it is flowing properly, salt crystals of the fill solution will form on the junction. If they do not, refer to the manufacturer's instructions for junction cleaning or replacement. Slow response or unstable ings in samples can be caused by a number of things. Those listed below assume that everything was fine in the calibration buffers. 1. Low ionic strength samples will tend to drift. You are trying to take an electrical measurement in a solution that is a very poor conductor. Try adding a drop of KCl fill solution to about 5 ml of the sample. In most cases it will not change the ph but will give the sample enough ionic strength for the electrode to finish the ing. 2. Non aqueous samples (organics) do not follow the normal ph scale and can cause some measuring problems. These solutions are usually low in ionic strength, may dehydrate the ph membrane and often cause the junction to plug due to incompatibility with the electrode fill solution. The most reliable way to ph organics is to dilute them with water until stable ings can be generated. 3. Concentrated samples can cause ph measuring errors. This is caused by problems with the ph sensing glass and its ability to distinguish the Hydrogen ion activity over the mass of other ions in the sample. The creation of new junction potentials due to KCl dissociation problems can also cause instability. The best solution is to dilute the samples into measurable ranges. For more information refer to the Corning Guide to ph Measurement Rev. A, 9/97

29 4.4.2 Problem Solving in Conductivity/TDS Meter Error Codes in Conductivity/TDS + Err 1 - measurement out of range Check sensor is connected and immersed in sample. Err 2 - cal 1 out of range Clean the sensor, or replace. Err 3 - cal 2 out of range Check correct standard is being used. Check correct solids factor is being used - for Corning standards use the following factors 84 µs/cm factor µs/cm factor ms/cm factor ms/cm factor 0.50 Clean the sensor, or replace. 4 If MTC is displayed, check connection to sensor/replace sensor. Data Entry Errors Entered solids factor value changes to 0.40 or the 442 will not accept solids factors outside this range. Entered temperature coefficient value changes to 0.0 or the 442 will not accept temperature coefficients outside this range Rev. A, 9/97 29

30 4 4.5 Meter Specifications Operating Ranges ph 0.00 to mv ±1999 mv Cond to 1000 ms/cm TDS 0.00 to 1000 g/l Resolution ph 0.01 mv 1 Cond variable TDS variable Relative Accuracy* ph ±0.01 mv ±1 mv Temp. ±0.4 C Cond. ±0.5% TDS ±0.5% Temp. ±0.4 C * ±1 least significant digit Calibration Points ph 3 of 3 Conductivity 2 of 5 Outputs Recorder (ph) Serial Size 10 x 8 x 4 inches (260 x 200 x 100 mm) Weight 2.4 lb (1.1 kg) Power Requirements The 443i is supplied with an appropriate power supply unit, e.g. USA/Japan V, 50/60Hz, 9VA Europe 230V 50Hz, 9.7VA Output from PSU 9V DC NOTE The 442 should only be used with the power supply unit provided. 442 Power Rating 0.6VA Specifications for ph/mv Isopotential Point ph 7.00 Temperature Compensation -5.0 to C, auto/manual Input Conditions ph impedance >10 12 ohms Rev. A, 9/97

31 4.5.2 Specifications for Conductivity/TDS Temperature Compensation 0.0 to 80.0 C (ATC) - set by the value of the temperature coefficient Auto Calibration Points Zero and 84 µs/cm, 1413 µs/cm, ms/cm or 80 ms/cm Solids Factor 0.40 to 1.00, selectable Reference Temperature 0.0 to 10.0%/ C, selectable Instrument temperature range as adjusted by temperature compensation: % = 0-80 C % = 0-60 C % = 0-50 C % = 0-40 C % = 0-35 C 4 Regulatory Compliance The 442 is manufactured in a FDA (Food & Drug Administration) and ISO 9001 approved plant (for Corning) and complies with the following regulatory standards: UL1262, CSA151, IEC1010. The 442 also complies with the European EMC Directives and therefore carries the CE mark. Environmental Compliance The casework components of the 442 are marked with the appropriate recycling identification symbol. The packaging is manufactured using recycled cardboard, and printed with water based ink. The packaging is recyclable. The manual is printed on environmentally friendly paper Rev. A, 9/97 31

32 Consumables and Accessories Catalog # Description Quantity Automatic Temperature Probe - Basic Electrode Fill Solution 3M KCl (125 ml) 6 bottles Electrode Storage Container Electrode Conditioning Solution (30 ml) 3 bottles Guide to ph Measurement ph Combination Electrode, 3 in 1 Refillable ph Combination Electrode, 3 in 1 Gel ph Combination Electrode, Hi-Performance ph 4.00 Buffer (500 ml) 2 bottles ph 7.00 Buffer (500 ml) 2 bottles ph Buffer (500 ml) 2 bottles ph 4.00 Buffer Sachets 30 packs ph 7.00 Buffer Sachets 30 packs ph Buffer Sachets 30 packs ph Buffer Multi-Pack Sachets 32 packs ph Electrode Rinse Sachets 30 packs Plate Carbon Conductivity Sensor Plate Glass Conductivity Sensor Plate Glass Conductivity Sensor Glass Flow-Through Cell Disposable Meter Cover Sensor Arm Assembly Guide to Conductivity/Dissolved Oxygen Conductivity Standard 1413µS/cm (500 ml) 1 bottle Conductivity Standard 12.88mS/cm (500 ml) 1 bottle Conductivity Standard 84µS/cm (460 ml) 1 bottle Conductivity Standard 80mS/cm (460 ml) 1 bottle Conductivity Standard 12.88mS/cm Sachets 30 packs Conductivity Standard 1413µS/cm Sachets 30 packs Conductivity Standard 84µS/cm Sachets 30 packs Conductivity Standard 80mS/cm Sachets 30 packs Power Supply, 110/120V - 50/60Hz Power Supply, 230V - 50Hz RS232C Cable Dot Matrix Printer with Cables Recorder Output Connector Shorting Test Clip 3 Warranty: Corning warrants this product to be free from defects in materials and workmanship. The warranty period for the meter is two (2) years from the date of purchase and the probe is six (6) months from the date of purchase. THIS WARRANTY IS MADE IN LIEU OF ALL OTHER WARRANTIES EXPRESSED OR IMPLIED INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. CORNING SHALL NOT BE LIABLE FOR ANY LOSS OR DAMAGES ARISING FROM THE USE OF THESE PRODUCTS NOR FOR CONSEQUENTIAL DAMAGES OF ANY KIND. In the event that a meter or probe fails under normal laboratory conditions within the specified period because of a defect in material or workmanship, Corning will, at its option, repair or replace the product. Contact Corning Customer Service for return authorization and shipping instructions at