450 ph/ion Meter. Instruction Manual

Transcription

1 450 ph/ion Meter Instruction Manual This manual contains complete instructions for setting up and using the 450 ph/ion 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 450 is intended for use by persons knowledgeable in safe laboratory practices. If the 450 is not used in accordance with these instructions for use, the protection provided by the equipment may be impaired. The 450 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 450 or power supply unit. Do not remove the covers Rev. A, 11/96 1

2 Contents 1 Set Up 1.1 Unpacking and Installation Input and Output Connections Display and Controls Programming Menu Overview Operation 2.1 Calibrating a ph Electrode ph Measurements mv Measurements Absolute mv Relative mv Calibrating an Ion Selective Electrode Concentration Measurements Automatic Endpoint (Auto Read) Temperature Measurements Karl Fischer Titrations Chart Recorder Interfacing via the RS232 Output Meter Programming 3.1 Calibration Menu Calibration Point Setting Last Calibration Recall Isopotential Point Setting (ph) Display Menu Channels to Display Units for Concentration to Display Resolution for ph to Display Rev. A, 11/96

3 Contents (cont) 3 Meter Programming (cont) 3.3 System Menu Time and Date Language Baud Rate Beeper on/off Temperature Menu Temperature Probe Selection Manual Temperature Set Limits Menu Alarm Visual and Audible On/Off Set High/Low Limits for ph Set High/Low Limits for Temperature Datalog Menu Datalogger On/Off Timer Setting Recall Logged Data Clearing Logged Data GLP (Good Laboratory Practice) Menu GLP On/Off Calibration Alarm Setting Entering an ID Number Diagnostics Menu Meter Self Test Meter Reset Rev. A, 11/96 3

4 Contents (cont) 4 Support Information 4.1 Basic Theory Operating Hints Maintenance Meter Maintenance Electrode Maintenance Problem Solving Meter Test Meter Error Codes Electrode Problem Solving Meter Specifications Consumables and Accessories... inside rear cover Warranty... inside rear cover Rev. A, 11/96

5 1.1 Unpacking and Installation 1. The main carton will contain the following: Meter with shorting (test) clips in the input sockets Meter Dust Cover Power Supply This Instruction Manual Memo Cards, English, French, German, Italian, Spanish Guide to ISE Measurements Warranty Card Calibration Certificate 1 2. If you ordered the meter with an electrode, electrode arm and accessories, the top tray of the main carton will contain these items. Refer to the accessories packing sheet for a list of the additional components. 3. Attach the electrode arm to the ph/ion meter: a. The electrode arm can be attached to the left or righthand side. Using the screwdriver supplied remove the appropriate end cap from the ph/ion meter. b. Slide the arm base into the recess and tighten the fixing screw. Replace the end cap. c. Fit the electrode arm onto the post. Adjust the tension screw as required. electrode arm arm base end cap fixing screw tension screw screwdriver 4. Fill in and return the warranty card. For your record make a note of the serial number, date of purchase and supplier on the inside front cover of this manual Rev. A, 11/96 5

6 1.2 Input and Output Connections 1 DC - power supply unit socket KF - polarizing current source for Karl Fischer titrations ATC - ATC (automatic temperature compensation) probe socket ph - combination or ph electrode sockets, Channel A & B A B DATA - data output socket, see Section 2.8 for interfacing details REC - recorder output socket, see Section 2.7 for details REF - reference electrode sockets, Channel A & B PT - PT1000 (automatic temperature compensation) probe sockets 1. Disconnect the shorting clips from the ph sockets and retain by clipping over the socket. If you are using two sensing electrodes connect them to Channel A and B. If you are using one electrode, connect it to Channel A. 2. Connect the reference electrode(s), if using, to the REF socket(s). 3. If you are using an ATC probe connect it to the ATC socket. If you are using a PT1000 probe connect it to the PT sockets. 4. Connect the power supply unit to the DC socket. 5. When the 450 is powered up it carries out a display self test Rev. A, 11/96

7 1.3 Display and Controls 1 mode prog auto Selects ph, mv, relative mv or concentration mode (for Channel A or Channel B). Accesses software menu from current mode. Exits software menu one step at a time. Selects automatic endpoint detection. on/off cal arrows Turns the display off, and places the meter in standby mode. Wakes the meter up. Starts a calibration sequence in ph, relative mv and concentration modes. Starts sample measurement in all modes. Press again to freeze display in manual endpoint mode. Starts and stops timed data logging. Returns to measurement from software menu. Selects options in software menu, and s data or selection. Used to move around software menu. numeric keypad Data entry keys, to set calibration buffers, date/time, high/low limits etc. Can also be used to move around software menu quickly Rev. A, 11/96 7

8 1.4 Programming Menu Overview 1 The 450 uses a menu system of software for the set up functions. There are eight main menus, these are: calibration, display, system, temp, limits, datalog, GLP, diagnostics. This chart shows the eight main menus and their sub routines. prog calibration display system temp limits datalog GLP diagnostics cal points channel time/date ATC type alarm on/off on/off self test last cal conc units language manual set limits timer cal alarm reset iso ph resolution baud temp recall data ID no. beeper clear data Use the arrow keys to move around the software menu. The numeric keypad can also be used as quick access keys. For example, to change the display resolution to X.XX, press prog then 2 (to access menu 2), 3 (to access sub routine 3), 2 (to select option 2). This is useful when operating the 450 remotely from a PC, see Section Rev. A, 11/96

9 1.4 Programming Menu Overview (cont) To access the menus: press prog the display shows three menus at a time (if you are using both measurement channels (A and B), you have to select which channel you want to set up). calibration display system > Press and to move round the menus.you can move either way, and the menu wraps round at each end. Each time you press an arrow key the next menu appears, e.g. press display system temp > 1 To access the menu sub routines, press or when your required menu is highlighted, e.g. to access the display menu sub routine press display system temp > channel conc units ph resolution Use to move down through the sub routines. To access your chosen sub routine press To choose from options displayed use and then press Before you can or change a value the value must be flashing, for example: cal 1 = or Press Change the flashing value using the keypad, then press again. Press to return directly to measurement Rev. A, 11/96 9

10 2.1 Calibrating a ph Electrode 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 2.5). If you are not using an ATC in the system, the temperature can be ed manually (see Section 3.4.2). If you have the 'auto ' feature (see Section 2.4) turned on, the meter will automatically endpoint when the ing is stable. To manually endpoint and freeze the display press 1 point calibration Place the tip of the electrode in the first buffer and press cal 2 If you are displaying both channel A and B, select the one you are calibrating and press The calibration buffer screen will display. Five calibration buffers are shown on the display. If you want to use other buffers, you will need to the values (see Section 3.1.1). At the measurement endpoint a tick ( ) will appear next to the calibration buffer and the electrode offset will display (in mv). Rinse the tip of the electrode with distilled or deionized water and goto ph Measurements (Section 2.1.1) or 2 point calibration. 2 point calibration Place the tip of the electrode in the second buffer and press At the measurement endpoint a tick ( ) will show next to the buffer and the electrode slope will display. cal Rinse the tip of the electrode with distilled or deionized water and goto ph Measurements (Section 2.1.1) or 3 point calibration Rev. A, 11/96

11 2.1 Calibrating a ph Electrode (cont) 3, 4 and 5 point calibration Repeat above procedure using the third, fourth and fifth buffers. NOTES The five buffers can be selected for calibration in any order. Use and to select the buffer you want to use for the calibration and press cal ph Measurements NOTE Good laboratory practice dictates that electrodes should be calibrated at least daily. Place the tip of the electrode in the sample and press to start the measurement. The decimal point will be flashing whenever the electrode is ing. If you are using the 'auto ' function the display freezes when a stable endpoint is reached (see Section 2.4). To manually freeze the display when the ing is stable, press 2.2 mv Measurements 2 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 Absolute mv Press mode until mv shows at the top of the display. Put the tip of the electrode in the sample and press meter will display absolute millivolts. The When the ing is stable, press use 'auto ', see Section 2.4). to freeze the display (or Rev. A, 11/96 11

12 2.2 mv Measurements (cont) Relative mv Press mode until Rel mv shows at the top of the display. Put the tip of the electrode in the reference solution and press cal The meter will be displaying absolute millivolts. When the ing is stable, press use 'auto ', see Section 2.4). to freeze the display (or The display will update to a relative mv value 0.0 mv. Put electrode in test sample and press (or use 'auto '). The meter will show the change in mv from 0.0 mv Calibrating an Ion Selective Electrode If you have the 'auto ' feature (see Section 2.4) turned on, the meter will automatically endpoint when the ing is stable. To manually endpoint and freeze the display, press To calibrate an electrode: Press cal If you are using both measurement channels (A and B), select the one you want to calibrate using and then press Five calibration standards are shown on the display. If you want to use other standards, you will need to the values (see Section 3.1.1). 1 point calibration Place the tip of the electrode in the first standard. At the measurement endpoint a tick ( ) appears. The electrode offset is displayed. To return to sample measurement press Rev. A, 11/96

13 2.3 Calibrating an Ion Selective Electrode (cont) 2 point calibration To continue with a 2 point calibration: Place the tip of the electrode in the second standard and press cal When the display freezes the electrode slope value will be displayed. To return to sample measurement press 3, 4 and 5 point calibration Repeat the procedure using the third, fourth and fifth calibration standard. NOTES The standard set for the first calibration standard is the isopotential point. The five standards can be selected for calibration in any order. Use and to select the standard you want to use for the calibration and press Concentration Measurements cal 2 We recommend regular calibration before sample measurements (see Section 2.3). To measure concentration: Place the tip of the electrode(s) in the sample and press The display will show the concentration of the sample. The units can be changed (see Section 3.2.2). If you are using a temperature probe, temperature of the sample will be displayed. If you are using 'Auto' endpoint the display will freeze automatically (see Section 2.4). To endpoint manually press Rev. A, 11/96 13

14 2.4 Automatic Endpoint (Auto Read) The 'auto ' function checks the electrode output for stability and automatically freezes the display when the ing appears stable. It can be used during calibration and routine measurements. Turn auto endpoint on by pressing auto A The auto endpoint indicator will appear at the top of the meter display. While the meter is ing, the decimal will flash. When the endpoint is reached, it will stop flashing. To start another ing press 2 To cancel auto endpoint press auto again Rev. A, 11/96

15 2.5 Temperature Measurements To measure temperature you must be using an ATC probe or the 3-in-1 Combination electrode which includes an ATC probe. If you do not have an ATC probe the temperature will default to 25 C or the temperature that you have set manually (see Section 3.4.2). If an ATC is in use the display will show ATC or PT1000 (see Section 3.4.1). If not the display will show MTC and 25 C (or the manually set temperature). The Model 450 uses the temperature value to correct the ph electrode slope for temperature. Be aware that ph meters do not correct the displayed values back to what they would be at 25 C. The ATC probe allows the meter to give the correct buffer value for the temperature at which it is being used. When a hot or cold sample is measured, the ATC probe will allow the meter to correct the calibration slope to the new temperature so that the ings are accurate for that temperature. Temperature should always be recorded along with the ph value. For others to duplicate your ings they must know what the sample temperature was when you it. The ph of most samples will change with temperature and very few will change by exactly the same amount. To know what the ph of a hot or cold sample is at room temperature, it must be measured at room temperature. 2 Buffer Temperature Correction Table If you use standard buffers (listed below) the 450 automatically corrects for temperature using the values shown in the table C C C C C C C C C C C Rev. A, 11/96 15

16 2.6 Karl Fischer Titrations The KF socket on the back of the meter provides a constant 1 ma polarizing current. This output may be used to polarize metallic electrode pairs for Karl Fischer moisture determinations or other dead-stop titrations. 2.7 Chart Recorder ve +ve REC Socket Polarity 2 The REC socket (2.5 mm phone jack) provides a voltage proportional to the displayed ing in ph, mv, relative mv and concentration modes. The polarity of the output is the same as the polarity of the input signal. NOTE The recorder output is only available for Channel A. Approximate Recorder Outputs ph - Output follows display and provides approximately 60 mv output per ph unit. This value will vary with changes in electrode slope. mv/relative mv - Output follows display, i.e. as display varies from to mv, output varies from to mv. concentration - Output depends on valency and charge of ionic species being measured, and is typically approximately ±60 or ±30 mv per concentration unit. The recorder output is not available for temperature ings Rev. A, 11/96

17 2.8 Interfacing via the RS232 Output The Model 450 can transmit data in RS232C Serial format to compatible devices such as Serial Printers and computers. The data can be received and manipulated by most data acquisition software packages. The high/low limits for ph process control are available at pins 8 and 9 on the DATA socket and can drive TTL or CMOS devices. The maximum source or sink current available is 20 ma. 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 450 output protocols are as follows: Pin Signal 1 not used 2 RS232 Tx (signal transmit) 3 RS232 Rx (signal receive) 4 not used 5 protective ground (0V) 6 CTS (clear to send) 7 not used 8 output 1 (0V within limit, 5V below low limit) 9 output 2 (0V within limit, 5V above high limit) 2 Type of communication - bi directional Baud rate (adjustable, see Section 3.3.3) Data format - 1 start bit 8 data bits 2 stop bits no parity protective ground (0V) 5 1 signal receive signal transmit 9 6 CTS low limit output high limit output Rev. A, 11/96 17

18 2.8 Interfacing via the RS232 Output (cont) Example Printout (RS232, 24 character printer) GLP ON 23/11/93 10:35:52 ID NUMBER 09 MODEL M450 ELECTRODE ID... CHANNEL A TEMP COMP MTC CAL C 7.000pH OFFSET 5.8mV NAME... GLP OFF S/N 1 10:41 23/11/93 A ph 25.0 C MTC M E/P B 0.98E 4mmol/L 25.0 C MTC M E/P NH3- GLP function selected Date and time ID number (user able) ph meter model number Electrode ID (e.g. serial number) Measurement channel identifier Temperature mode (manual) Cal point, temperature and result Electrode offset Authorization GLP function deselected Sample number, time and date Channel, result, temperature and temp. mode Endpoint method (manual) Channel, result, temperature and temp. mode Endpoint method (manual), and electrode type Rev. A, 11/96

19 2.8 Interfacing via the RS232 Output (cont) To move around the software menu easily you can use the numeric keypad as quick access keys. See Section 1.4 for a menu overview, and the relevant quick keys. The 450 can also be controlled by a PC with terminal software. To turn on the remote function send: TON To return to a known position in the software menu send: S (for standby) H (for home). This returns the 450 to ph mode, channel A measurement only. To turn the remote function off send: X NOTE Allow a 1 second delay between sending characters. RS232 Keyboard Definitions Key RS232 Key RS232 Key RS232 Command Command Command mode M U 5 5 prog auto P A D on/off S > 8 8 cal C R E Rev. A, 11/96 19

20 3.1 Calibration Menu calibration cal points last cal iso This menu allows you to set 5 calibration points for ph or concentration; recall the time and date of the last calibration and set the isopotential point for ph. Default refers to the factory setting which the 450 uses if no information is ed Calibration point setting Press or when the cal points sub routine is highlighted. If you the cal points sub routine from ph mode, the cal points for ph calibration are set up. If you from concentration mode, the concentration calibration points are set up, and the standard set as the first calibration point is the isopotential point. Use and to select the calibration point you want to change and press The display flashes showing that the value can be changed. Enter the required value using the keypad and press 3 # appears if you set a ph calibration value to a standard buffer. The 450 stores temperature corrected values for the standard buffers (see Section 2.5). The next cal point is highlighted. If you want to change this next point, press and continue as before. Use and to select another calibration point to change, OR Rev. A, 11/96

21 3.1 Calibration Menu (cont) Calibration point setting (cont) press or prog to leave the sub routine without any further changes. Press to return directly to measurement Last calibration recall Press or when last cal sub routine is highlighted. The time and date of the last calibration (ph OR concentration) is shown. (The time and date must be set, see Section ) press or prog to leave the sub routine. Press to return directly to measurement Isopotential point setting (ph) The default isopotential point is ph7.00 (0.00mV). See Section 4 for further information. Press or when iso sub routine is highlighted. Press the display flashes showing that the value can be changed. Enter the required value using the keypad and press Press to return directly to measurement Rev. A, 11/96 21

22 3.2 Display Menu display channel conc units ph resolution This menu allows you to select measurement channel A, B or A & B; select the units of measurement for concentration and change the display resolution for ph mode. Default refers to the factory setting, which the 450 uses if no information is ed Channels to display The default selection is channel A only. Press or when the channel sub routine is highlighted. Use and to select the measurement channel(s) you want to use and press Press to return directly to measurement Units for concentration to display 3 The default setting is no units (blank) selected. The units available are ppm, mmol/l, % and M. eq. Press or when the conc units sub routine is highlighted. Use and to select the units of measurement you want Press NOTE to use and press to return directly to measurement. Calibrate the 450 in the units you want to use for sample measurement. Changing the units does not change the ing; for example, the 450 will not convert from ppm to mmol/l Rev. A, 11/96

23 3.2 Display Menu (cont) Resolution for ph to display The default setting is maximum resolution. Press or when the ph resolution sub routine is highlighted. Use and to select the resolution you want to use and press Press to return directly to measurement Rev. A, 11/96 23

24 3.3 System Menu system time/date language baud beeper This menu allows you to set the time and date; set the language for the display; set the baud rate for data output and turn the key press beeper on or off. Default refers to the factory setting, which the 450 uses if no information is ed Time and date Press or when the time/date sub routine is highlighted. Use and to select the time display, or one of the date options. Press the display flashes showing that the value can be changed. Enter the time or date using the keypad and and press For example, to 4/12/96: press Press to return directly to measurement Language Default language is English. Press or when language sub routine is highlighted. Use and to select the language you want to use and press There will be a short delay while the 450 initializes the language. Press to return directly to measurement Rev. A, 11/96

25 3.3 System Menu (cont) Baud rate Default baud rate for the DATA socket is The other options available are 300, 4800, 7200, (See Section 2.8 for further information on the DATA socket). Press or when the baud sub routine is highlighted. Use and to select the baud rate you want to use and press Press to return directly to measurement Beeper on/off A beep accompanies valid key presses. This routine allows you to turn the beeper off. Default setting is beeper on. Press or when the beeper sub routine is highlighted. Use and to select beeper on or off and press Press to return directly to measurement Rev. A, 11/96 25

26 3.4 Temperature Menu temptemp mode ATC type manual This menu allows you to select the type of temperature probe you want to use (standard ATC or PT1000), or to the temperature of solutions manually. Default refers to the factory setting, which the 450 uses if no information is ed Temperature probe selection Default probe is ATC. Press or when the ATC type sub routine is highlighted. Use and to select which mode you want to use and press Press to return directly to measurement Manual temperature set 3 Default temperature is 25 C. Press or when the manual sub routine is highlighted. Press the display flashes showing that the temperature can be changed. Enter the required temperature using the keypad and press Press to return directly to measurement. NOTE Temperature can be ed manually when a temperature probe is connected, but the 450 will use the temperature probe value Rev. A, 11/96

27 3.5 Limits Menu limits alarm set limits temp This menu allows you to set high and low limits to monitor sample measurement in ph mode, and also for temperature ings. The alarm (to alert you to out of limits ings) can be set to show on display only, to beep and show on display, or it can be turned off. The limits for ph are available at the DATA socket. Default refers to the factory setting, which the 450 uses if no information is ed Alarm visual and audible on/off Default setting is alarm off. Press or when the alarm sub routine is highlighted. Use and to select the alarm setting you want to use and press Press to return directly to measurement Set high/low limits for ph Press or when the set limits sub routine is highlighted. Use and to select high or low limit and press The display flashes showing that the limit can be changed. Enter the required limit using the keypad and press 3 The maximum limits that can be set are: high and low Rev. A, 11/96 27

28 3.5 Limits Menu (cont) Set high/low limits for ph (cont) Repeat for other limit. Press to return directly to measurement. The high/low limits for ph are available at the DATA socket. See Section 2.8 for further information Set high/low limits for temperature Press or when the temp sub routine is highlighted. Use and to select high or low limit and press The display flashes showing that the limit can be changed. Enter the required limit using the keypad and press The maximum limits that can be set are: high and low Repeat for other limit. Press to return directly to measurement Rev. A, 11/96

29 3.6 Datalog Menu datalog on/off timer recall data clear data This menu allows you to set up timed measurements and print, or print and log, the last 100 results. The data can be recalled to the display, or to an external printer. The timer must be used with the datalog function. Default refers to the factory setting, which the 450 uses if no information is ed Datalogger on/off Default setting is data logging off. Press or when the on/off sub routine is highlighted. Use and to select the option you want to use and press Press to return directly to measurement. NOTE You can use the on/off function to temporarily stop data logging, without cancelling the timer and other options. Reselect an on option to restart data logging Timer setting Press or when the timer sub routine is highlighted. Press Rev. A, 11/96 the display flashes showing that the interval can be changed. Enter the timer interval using the keypad and and press For example, to 1 hour 30 minutes 30 seconds: press

30 3.6 Datalog Menu (cont) Timer setting (cont) Press to return directly to measurement. NOTES starts and stops data logging. Use the following checklist to make sure you have set datalogging up correctly: check manual endpoint facility is selected, not automatic (see Section 2.4). check 'datalogging on' is selected (print only or store & print - see Section 3.6.1). check a timer interval is ed (Section 3.6.2). check the decimal point is flashing (i.e. the 450 is measuring) when you return to measurement mode. If it is not press sequence. to start the measurement You can change mode, or channel, or other variables while using the timer facility. The sample number will restart at 1. The 450 can log up to 100 results. After 100 results the 450 starts to overwrite the first results logged. So, if for example 150 measurements have been made, the 450 will retain the data for results 51 to Recall logged data Press or when the recall data sub routine is highlighted. Use and to select recall option and press 3 If you recall the data to the external printer, it will print all the data logged (up to 100 results) Rev. A, 11/96

31 3.6 Datalog Menu (cont) Recall logged data (cont) If you recall the data to the display it is shown 4 results at a time. Use and to scroll through the results, or press sample number to go directly to a result. NOTE Press If you have changed mode, or channel, during measurement there will be more than one sample number 1, etc. Press with the same number. to leave the sub routine. twice to see other samples Clearing logged data Press or when the clear data sub routine is highlighted. To clear all the data held in memory press To leave the routine without clearing data press Rev. A, 11/96 31

32 3.7 GLP (Good Laboratory Practice) Menu GLP on/off cal alarm ID no. This menu allows you to set up the good laboratory practice (GLP) function. The 450 can be set to force calibration after a preset time interval, after a preset number of samples, or both. The printout shows all the calibration information. If using both measurement channels (A and B) the GLP function applies to both channels - the channels cannot be set up individually. Default refers to the factory setting, which the 450 uses if no information is ed GLP on/off Default setting is GLP off. Press or when the GLP sub routine is highlighted. Use and to select GLP on or off and press Press to return directly to measurement Calibration alarm setting Press or when the cal alarm sub routine is highlighted. Use and to select time interval or number of samples. Press the display flashes showing that the value can be changed. The time interval can be set between 1 second and 23 hours 59 minutes and 59 seconds; the number of samples can be set between 0 and Rev. A, 11/96

33 3.7 GLP Menu (cont) Calibration alarm setting (cont) Enter the required value using the keypad and press Press to return directly to measurement. After the time interval has elapsed, or the number of samples have been measured, a message will appear on the 450 display requesting calibration. The 450 will not allow further sample measurement until a calibration has been carried out Entering an ID number Press or when the ID no. sub routine is highlighted. Press the display flashes showing that the number can be changed. Enter the required ID number (e.g. operator ID or meter serial number) using the keypad and press Up to eight digits can be ed. Press to return directly to measurement. The ID number is printed with the calibration information Rev. A, 11/96 33

34 3.8 Diagnostics Menu diagnostics self test reset This menu allows you to request a self test - the 450 will test the keyboard controls, ROM, display, RS232 and RAM. You can also reset all variable information to the default values. Default refers to the factory setting, which the 450 uses if no information is ed Meter self test Press or when the self test sub routine is highlighted. Press to the self test. The 450 displays the keyboard test. Press each control and check that the highlighting on the display goes off. When all the controls have been checked the 450 will test the ROM ( only memory) and then test the display. Watch the display test, and check for any missing segments. The 450 will then send the following characters to the DATA socket (RS232) A B C D E F G H I J K L M N 3 check the printout on the external printer. The 450 finally tests the RAM (random access memory). There will be a short delay while the RAM is tested. A tick ( ) appears after each test. At the end of the self test routine press to measurement. to return directly Rev. A, 11/96

35 3.8 Diagnostics Menu (cont) Meter reset Press or when the reset sub routine is highlighted. To reset variable information to default values press NOTE This will also clear any data stored during data logging. The 450 will reset all values to default except baud rate, and reinitialize the display. Press to leave the sub routine without resetting data Rev. A, 11/96 35

36 4.1 Basic Theory 4 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 + ] 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 450 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 T = the temperature (Kelvin) R = the gas constant n = the ionic charge F = the Faraday constant 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. 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 Rev. A, 11/96

37 4.2 Operating Hints This section gives some brief operating hints and good laboratory practices to help assure trouble free ph measurements. 1. New electrodes (or electrodes that have been in storage) should be conditioned in one inch (25 mm) 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 one point calibration may be suitable for some applications, we recommend that a two 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. 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. Do not use calibration buffers after the expiration date printed on the package. Keep the bottles tightly capped and stored according to the manufacturer's instructions. Never put used buffer back into the bottle of new buffer. 7. For small sample volumes, make sure that both the ph bulb and the reference junction are in contact with the sample. 8. 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. 9. Samples must be in solution (water). You cannot measure the ph of a dry sample. Refer to the electrode manufacturer's instructions for proper electrode care and maintenance. See Section for general electrode maintenance and Section for problem solving Rev. A, 11/96 37

38 4.3 Maintenance Meter Maintenance The Model 450 Meter needs no maintenance except for an occasional wipe with a damp cloth. The front panel is made of polyester and is not affected by most solvents. Polyester 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 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 (25 mm) 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. 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 Rev. A, 11/96

39 4.3 Maintenance (cont) Electrode Maintenance (cont) 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 Problem Solving Most problems are caused by electrode faults rather than by the Model 450 but power fluctuations can corrupt calibration values being held in the meter memory Meter Test To assure that the meter memory and calibration points have not been corrupted by power fluctuations, perform the Meter Test as follows: 1. Press or when the self test sub routine is highlighted, see Section The 450 tests the ROM and RAM, and allows the keyboard controls, RS232 output and display to be checked. 2. Disconnect the electrode from the ph socket, and connect the shorting clip (or shorting plug). Select mv mode. The 450 displays 0 ±4 mv. Disconnect the shorting clip (or shorting plug), and the ing changes. Test both channels. 3. Disconnect the temperature probe the display shows MTC. Reconnect the temperature probe (or electrode incorporating ATC); the display shows ATC or PT1000 and the ambient temperature. 4. Reconnect electrode Rev. A, 11/96 39

40 4.4 Problem Solving (cont) Meter Test (cont) 4 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 Error codes are designed to give the user information on electrode performance problems. E1 E2 E3 E4 E5 ph Electrode is not ing a value close enough to the first calibration buffer. Electrode needs maintenance (see Section 4.4.3). ph Electrode is not giving a value within 0.5 ph of the second calibration buffer. Electrode needs maintenance. Ion Selective Electrode is not giving sufficient change between calibration points. Change must be at least 15 mv but not more than 90 mv. Check calibration standards and electrode. Temperature of ph buffer outside limits of 0 to 50 C. Check manually ed temperature or replace ATC probe. Calibration points must have different values. Check cal point settings (see Section 3.1.1). ph buffer is outside range of 0 to 14. Check cal point settings. E6 Illegal date or time ed (see Section 3.3.1). 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 and or if the fill solution in the electrode is low or wrong. Dashes in the temperature mode indicates that the ATC has failed. Illegal limit Limit ed is outside range. Check value Rev. A, 11/96

41 4.4 Problem Solving (cont) Meter Error Codes (cont) 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 4.1 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. 4 Refer to the electrode manufacturer s instructions for full details on maintenance, cleaning and reconditioning electrodes Electrode Problem Solving 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 Rev. A, 11/96 41

42 4.4 Problem Solving (cont) Electrode Problem Solving (cont) 4 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 be very drifty. 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. Information on ISE electrodes can be found in the Corning Guide to ISE Measurement Rev. A, 11/96

43 4.5 Meter Specifications Operating Ranges ph to mv ± Rel. mv ± Temp. 30 to 130 C Conc to Resolution ph / 0.01 / 0.1 mv 0.1 Rel. mv 0.1 Temp. 0.1 C Relative Accuracy* ph ±0.001 mv ±0.2 Rel. mv ±0.2 Temp. NTC C ±1% 0-50 C ±0.5 C C ±1% PT C ±0.4 C C ±0.2 C C ±0.4 C Conc. ±0.5% * ±1 least significant digit Time 0 to 23 hours 59 minutes Timer User selectable 0 seconds to 11 hours 59 mins 59 secs Memory 100 memories Isopotential Point ph, user adjustable ph Calibration 5 point Temperature Compensation 5 to 105 C, automatic and manual Display Dot matrix LCD display Outputs RS232 Recorder (Channel A only) Karl Fischer Input Conditions Impedance greater than ohms Operating Conditions Operating temperature: 5 to 40 C Operating humidity: max 80% at 35 C (non condensing) Installation category 2 Pollution category degree 2 Size / Weight 10 x 8 x 4 inches (255 x 200 x 95 mm) / 2.9 lbs (1.3 kg) Power Requirements The 450 is supplied with an appropriate power supply unit, e.g. USA/Japan 100V - 120V 50/60Hz, 9VA Europe 230V 50Hz, 9.7VA Output from PSU 9V DC NOTE The 450 should only be used with the power supply unit provided. 450 Power Rating 4.5VA Rev. A, 11/96 43

44 4 4.5 Meter Specifications (cont) Regulatory Compliance The 450 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 450 also complies with the European EMC Directives and therefore carries the CE mark. Environmental Compliance The casework components of the 450 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, 11/96

45 Consumables and Accessories Catalog # Description Quantity Automatic Temperature Probe - Basic Automatic Temperature Probe - PT Disposable Meter Cover Electrode Arm Assembly Electrode Fill Solution 3M KCl (125 ml) 6 bottles Electrode Storage Container Electrode Conditioning Solution (30 ml) 3 bottles Guide to ph Measurement Guide to ISE 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 Power Supply, 100/120V - 50/60Hz Power Supply, 230V - 50Hz RS232C Cable Shorting Test Clip Dot Matrix Printer with Cables 1 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

46 1992. All rights reserved. Corning Incorporated Science Products Division Corning, New York USA Telephone: (US and Canada) (Outside US) Fax: ? Rev. A, 6/96