450 pH/ion Meter Instruction Manual - Cole-Parmer · Instruction Manual This manual contains ... likely to cause interference in which case the user at his own expense ... For example,

1109120-1 Rev. A, 11/96

Instruction ManualThis manual contains complete instructions for setting up and usingthe 450 pH/ion meter. Applications information is also available.

The information contained in this manual was correct at the time ofgoing to print. However, we continue to improve products and reservethe right to change specifications, equipment and maintenanceprocedures at any time.

This manual is copyrighted, and all rights are reserved. No part ofthis manual may be reproduced by any means or in any form withoutprior consent in writing.

The power supply unit is classed as IEC Class II equipment(equipment providing an adequate degree of protection againstelectric shocks, in which additional safety precautions, for example,double or reinforced insulation, are included). The 450 is intended foruse by persons knowledgeable in safe laboratory practices. If the 450is not used in accordance with these instructions for use, theprotection provided by the equipment may be impaired.

The 450 is suitable for direct current only.

This equipment generates, uses and can radiate radio frequencyenergy and if not installed and used in accordance with theinstruction manual, may cause interference with radiocommunications. It has been tested and found to comply with thelimits for a Class A computing device pursuant to Subpart J ofPart 15 of FCC Rules, which are designed to provide reasonableprotection against such interference when operated in a commercialenvironment. Operation of this equipment in a residential area islikely to cause interference in which case the user at his own expensewill be required to take whatever measures may be required tocorrect the interference.

There are no user replaceable parts in the 450 or power supply unit.Do not remove the covers.

450 pH/ion Meter

2 109120-1 Rev. A, 11/96

Contents

1 Set Up

1.1 Unpacking and Installation ................................................ 51.2 Input and Output Connections........................................... 6

1.3 Display and Controls ......................................................... 7

1.4 Programming Menu Overview ........................................... 8

2 Operation

2.1 Calibrating a pH Electrode .............................................. 102.1.1 pH Measurements ........................................................... 11

2.2 mV Measurements .......................................................... 112.2.1 Absolute mV .................................................................... 112.2.2 Relative mV ..................................................................... 12

2.3 Calibrating an Ion Selective Electrode ............................ 122.3.1 Concentration Measurements ......................................... 13

2.4 Automatic Endpoint (Auto Read) ..................................... 14

2.5 Temperature Measurements ........................................... 15

2.6 Karl Fischer Titrations ..................................................... 16

2.7 Chart Recorder ................................................................ 16

2.8 Interfacing via the RS232 Output .................................... 17

3 Meter Programming

3.1 Calibration Menu ............................................................. 203.1.1 Calibration Point Setting .................................................. 203.1.2 Last Calibration Recall .................................................... 213.1.3 Isopotential Point Setting (pH) ........................................ 21

3.2 Display Menu ................................................................... 223.2.1 Channels to Display......................................................... 223.2.2 Units for Concentration to Display ................................... 223.2.3 Resolution for pH to Display ............................................ 23

3109120-1 Rev. A, 11/96

Contents (cont)

3 Meter Programming (cont)

3.3 System Menu ................................................................... 243.3.1 Time and Date ................................................................. 243.3.2 Language ......................................................................... 243.3.3 Baud Rate ........................................................................ 253.3.4 Beeper on/off ................................................................... 25

3.4 Temperature Menu .......................................................... 263.4.1 Temperature Probe Selection ......................................... 263.4.2 Manual Temperature Set ................................................. 26

3.5 Limits Menu ..................................................................... 273.5.1 Alarm Visual and Audible On/Off .................................... 273.5.2 Set High/Low Limits for pH .............................................. 273.5.3 Set High/Low Limits for Temperature .............................. 28

3.6 Datalog Menu .................................................................. 293.6.1 Datalogger On/Off ........................................................... 293.6.2 Timer Setting ................................................................... 293.6.3 Recall Logged Data ......................................................... 303.6.4 Clearing Logged Data ..................................................... 31

3.7 GLP (Good Laboratory Practice) Menu ........................... 323.7.1 GLP On/Off ...................................................................... 323.7.2 Calibration Alarm Setting ................................................. 323.7.3 Entering an ID Number .................................................... 33

3.8 Diagnostics Menu ............................................................ 343.8.1 Meter Self Test ................................................................ 343.8.2 Meter Reset ..................................................................... 35

4 109120-1 Rev. A, 11/96

Contents (cont)

4 Support Information

4.1 Basic Theory .................................................................... 36

4.2 Operating Hints ................................................................ 37

4.3 Maintenance .................................................................... 384.3.1 Meter Maintenance .......................................................... 384.3.2 Electrode Maintenance .................................................... 38

4.4 Problem Solving .............................................................. 394.4.1 Meter Test ....................................................................... 394.4.2 Meter Error Codes ........................................................... 404.4.3 Electrode Problem Solving .............................................. 41

4.5 Meter Specifications ........................................................ 43

Consumables and Accessories ............................... inside rear cover

Warranty .................................................................. inside rear cover

5109120-1 Rev. A, 11/96

1.1 Unpacking and Installation

1. The main carton will contain the following:Meter with shorting (test) clips in the input socketsMeter Dust CoverPower SupplyThis Instruction ManualMemo Cards, English, French, German, Italian, SpanishGuide to ISE MeasurementsWarranty CardCalibration Certificate

2. If you ordered the meter with an electrode, electrode armand accessories, the top tray of the main carton willcontain these items. Refer to the accessories packing sheetfor 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 right-

hand side. Using the screwdriver supplied remove theappropriate end cap from the pH/ion meter.

b. Slide the arm base into the recess and tighten the fixingscrew. Replace the end cap.

c. Fit the electrode arm onto the post. Adjust the tensionscrew as required.

4. Fill in and return the warranty card. For your record makea note of the serial number, date of purchase and supplieron the inside front cover of this manual.

1

electrode arm

arm base

fixing screw

end cap

screwdrivertension screw

6 109120-1 Rev. A, 11/96

DC - powersupply unitsocket

KF - polarizingcurrent sourcefor Karl Fischertitrations1

1.2 Input and Output Connections

1. Disconnect the shorting clips from the pH sockets andretain by clipping over the socket. If you are using twosensing electrodes connect them to Channel A and B. If youare using one electrode, connect it to Channel A.

2. Connect the reference electrode(s), if using, to the REFsocket(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 PTsockets.

4. Connect the power supply unit to the DC socket.

5. When the 450 is powered up it carries out a display selftest.

ATC - ATC (automatic temperaturecompensation) probe socket

pH - combination or pH electrodesockets, Channel A & B

PT - PT1000(automatictemperaturecompensation)probe sockets

DATA - dataoutput socket,see Section 2.8for interfacingdetails

REC - recorderoutput socket,see Section 2.7for details

REF -referenceelectrodesockets,Channel A & B

A B

7109120-1 Rev. A, 11/96

1

arrows

Selects pH, mV, relative mV or concentration mode (forChannel A or Channel B).

Accesses software menu from current mode. Exitssoftware␣ menu one step at a time.

Selects automatic endpoint detection.

Turns the display off, and places the meter in standbymode. Wakes the meter up.

Starts a calibration sequence in pH, relative mV andconcentration modes.

Starts sample measurement in all modes. Press again tofreeze display in manual endpoint mode. Starts and stopstimed data logging. Returns to measurement fromsoftware␣ menu.

Selects options in software menu, and enters data orselection.

Used to move around software menu.

Data entry keys, to set calibration buffers, date/time,high/low limits etc. Can also be used to move aroundsoftware menu quickly.

numerickeypad

mode

prog

on/off

read

enter

autoread

cal

1.3 Display and Controls

8 109120-1 Rev. A, 11/96

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1.4 Programming Menu Overview

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9109120-1 Rev. A, 11/96

1.4 Programming Menu Overview (cont)

To access the menus:

press the display shows three menus at a time (if you areusing both measurement channels (A and B), you haveto select which channel you want to set up).

Press and to move round the menus.You can moveeither way, and the menu wraps round ateach end. Each time you press an arrow keythe next menu appears, e.g. press

< calibration display system >

< display system temp >

To access the menu sub routines, press or whenyour required menu is highlighted,

e.g. to access the display menu sub routine press

< display system temp >

channel

conc units

pH resolution

To access your chosen sub routine press or

To choose from options displayed use and then

press

Before you can enter or change a value the value must beflashing, for example: cal 1 = 7.000

Press Change the flashing value using the keypad, then

press again.

Press to return directly to measurement.

prog

< <<

enter <

<

enter

<< <

enter

enter

enter

enter

read

1

Use to move down through thesub routines.

10 109120-1 Rev. A, 11/96

2

2.1 Calibrating a pH Electrode

If you are using an ATC probe (or an electrode incorporatingATC), temperature is being measured and the buffer value isbeing corrected for temperature (see Section 2.5). If you are notusing an ATC in the system, the temperature can be enteredmanually (see Section 3.4.2).

If you have the 'auto read' feature (see Section 2.4) turned on,the meter will automatically endpoint when the reading is stable.To manually endpoint and freeze the display press

1 point calibrationPlace the tip of the electrode in the first buffer and press

If you are displaying both channel A and B, select the one youare calibrating and press

The calibration buffer screen will display. Five calibrationbuffers are shown on the display. If you want to use otherbuffers, you will need to enter the values (see Section 3.1.1). Atthe measurement endpoint a tick (✔) will appear next to thecalibration buffer and the electrode offset will display (in mV).

Rinse the tip of the electrode with distilled or deionized waterand goto pH Measurements (Section 2.1.1) or 2 point calibration.

2 point calibrationPlace the tip of the electrode in the second buffer and press

At the measurement endpoint a tick (✔) will show next to thebuffer and the electrode slope will display.

Rinse the tip of the electrode with distilled or deionized waterand goto pH Measurements (Section 2.1.1) or 3 point calibration.

read

cal

enter

cal

11109120-1 Rev. A, 11/96

2.1 Calibrating a pH Electrode (cont)

3, 4 and 5 point calibrationRepeat above procedure using the third, fourth and fifth buffers.

NOTES The five buffers can be selected for calibration in anyorder.

Use and to select the buffer you want to

use for the calibration and press

2.1.1 pH Measurements

NOTE Good laboratory practice dictates that electrodesshould be calibrated at least daily.

Place the tip of the electrode in the sample and press tostart the measurement. The decimal point will beflashing whenever the electrode is reading.

If you are using the 'auto read' function the display freezes whena stable endpoint is reached (see Section 2.4). To manually freeze

the display when the reading is stable, press

2.2 mV Measurements

The millivolt capability of pH meters can be used to determine theactual slope of pH electrodes but is most frequently used for doingpotentiometric readings or titrations with Platinum Oxidation-Reduction electrodes.

2.2.1 Absolute mV

Press until mV shows at the top of the display.

Put the tip of the electrode in the sample and press Themeter will display absolute millivolts.

When the reading is stable, press to freeze the display (oruse 'auto read', see Section 2.4).

2read

read

mode

read

read

< <cal

12 109120-1 Rev. A, 11/96

2

2.2 mV Measurements (cont)

2.2.2 Relative mV

Press until Rel mV shows at the top of the display.

Put the tip of the electrode in the reference solution and press

The meter will be displaying absolute millivolts.

When the reading is stable, press to freeze the display (oruse 'auto read', see Section 2.4).

The display will update to a relative mV value 0.0 mV.

Put electrode in test sample and press (or use

'auto read'). The meter will show the change in mV from 0.0 mV.

2.3 Calibrating an Ion Selective Electrode

If you have the 'auto read' feature (see Section 2.4) turned on,the meter will automatically endpoint when the reading is stable.

To manually endpoint and freeze the display, press

To calibrate an electrode:

Press If you are using both measurement channels (Aand B), select the one you want to calibrate

using and then␣ press

Five calibration standards are shown on the display. If you wantto use other standards, you will need to enter the values (seeSection 3.1.1).

1 point calibrationPlace the tip of the electrode in the first standard. At themeasurement endpoint a tick (✔) appears.

The electrode offset is displayed.

To return to sample measurement press

read

cal

enter

< <

read

read

mode

read

cal

13109120-1 Rev. A, 11/96

2.3 Calibrating an Ion Selective Electrode (cont)

2 point calibrationTo continue with a 2 point calibration:

Place the tip of the electrode in the second standard and

press

When the display freezes the electrode slope value will bedisplayed.

To return to sample measurement press

3, 4 and 5 point calibrationRepeat the procedure using the third, fourth and fifth calibrationstandard.

NOTES The standard set for the first calibration standard isthe isopotential point.

The five standards can be selected for calibration inany order.

Use and to select the standard you want to

use for the calibration and press

2.3.1 Concentration Measurements

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 unitscan be changed (see Section 3.2.2). If you are using atemperature probe, temperature of the sample will be displayed.

If you are using 'Auto' endpoint the display will freezeautomatically (see Section 2.4). To endpoint manually

press

2read

cal

read

< <

cal

read

14 109120-1 Rev. A, 11/96

2.4 Automatic Endpoint (Auto Read)

The 'auto read' function checks the electrode output for stabilityand automatically freezes the display when the reading appearsstable. It can be used during calibration and routinemeasurements.

Turn auto endpoint on by pressing

The auto endpoint indicator will appear at the top of themeter display. While the meter is reading, the decimal will flash.When the endpoint is reached, it will stop flashing.

To start another reading press

To cancel auto endpoint press again.

2

autoread

read

autoread

A

15109120-1 Rev. A, 11/96

2.5 Temperature Measurements

To measure temperature you must be using an ATC probe or the3-in-1 Combination electrode which includes an ATC probe. Ifyou do not have an ATC probe the temperature will default to25°C or the temperature that you have set manually (see Section3.4.2). 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 (orthe manually set temperature).

The Model 450 uses the temperature value to correct the pHelectrode slope for temperature. Be aware that pH meters do notcorrect the displayed values back to what they would be at 25°C.The ATC probe allows the meter to give the correct buffer valuefor the temperature at which it is being used. When a hot or coldsample is measured, the ATC probe will allow the meter tocorrect the calibration slope to the new temperature so that thereadings are accurate for that temperature.

Temperature should always be recorded along with the pH value.For others to duplicate your readings they must know what thesample temperature was when you read it. The pH of mostsamples will change with temperature and very few will changeby exactly the same amount. To know what the pH of a hot orcold sample is at room temperature, it must be measured atroom temperature.

Buffer Temperature Correction Table

If you use standard buffers (listed below) the 450 automaticallycorrects for temperature using the values shown in the table.

1.679 4.000 4.008 4.010 6.860 6.865 7.000 7.413 9.180 9.210 10.010

0°C 1.666 4.000 4.003 4.010 6.980 6.948 7.120 7.534 9.464 9.520 10.3205°C 1.668 4.000 3.999 4.010 6.950 6.951 7.090 7.500 9.395 9.450 10.25010°C 1.670 4.000 3.998 4.000 6.920 6.923 7.060 7.472 9.332 9.380 10.18015°C 1.672 4.000 3.999 4.000 6.900 6.900 7.040 7.448 9.276 9.320 10.12020°C 1.675 4.000 4.002 4.000 6.880 6.881 7.020 7.429 9.225 9.260 10.060

25°C 1.679 4.000 4.008 4.010 6.860 6.865 7.000 7.413 9.180 9.210 10.010

30°C 1.683 4.010 4.015 4.010 6.850 6.853 6.990 7.400 9.139 9.160 9.97035°C 1.688 4.020 4.024 4.020 6.840 6.844 6.980 7.389 9.102 9.110 9.93040°C 1.694 4.030 4.035 4.030 6.810 6.838 6.980 7.380 9.068 9.060 9.89045°C 1.700 4.040 4.047 4.040 6.830 6.834 6.970 7.373 9.038 9.030 9.86050°C 1.707 4.060 4.060 4.060 6.830 6.833 6.970 7.367 9.011 8.990 9.830

2

16 109120-1 Rev. A, 11/96

—ve

+ve

2.6 Karl Fischer Titrations

The KF socket on the back of the meter provides a constant 1 mApolarizing current. This output may be used to polarize metallicelectrode pairs for Karl Fischer moisture determinations or otherdead-stop titrations.

2.7 Chart Recorder

REC Socket Polarity

The REC socket (2.5 mm phone jack) provides a voltageproportional to the displayed reading in pH, mV, relative mV andconcentration modes. The polarity of the output is the same asthe polarity of the input signal.

NOTE The recorder output is only available for Channel A.

Approximate Recorder OutputspH - Output follows display and provides approximately 60 mVoutput per pH unit. This value will vary with changes inelectrode slope.

mV/relative mV - Output follows display, i.e. as display variesfrom –1999.9 to 1999.9 mV, output varies from –1999.9 to+1999.9 mV.

concentration - Output depends on valency and charge of ionicspecies being measured, and is typically approximately ±60 or±30 mV per concentration unit.

The recorder output is not available for temperature readings.

2

17109120-1 Rev. A, 11/96

2.8 Interfacing via the RS232 Output

The Model 450 can transmit data in RS232C Serial format tocompatible devices such as Serial Printers and computers. Thedata can be received and manipulated by most data acquisitionsoftware packages.

The high/low limits for pH process control are available at pins 8and 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 computersis part number 477788 and can be ordered from your distributor.The pin configuration of that connector and Model 450 outputprotocols are as follows:

Pin Signal1 not used2 RS232 Tx (signal transmit)3 RS232 Rx (signal receive)4 not used5 protective ground (0V)6 CTS (clear to send)7 not used8 output 1 (0V within limit, 5V below low limit)9 output 2 (0V within limit, 5V above high limit)

Type of communication - bi directionalBaud rate - 1200 (adjustable, see Section 3.3.3)Data format - 1 start bit

8 data bits2 stop bitsno parity

protective ground (0V)

CTS

signal receive

signal transmit

low limit output

high limit output

15

69

2

18 109120-1 Rev. A, 11/96

2.8 Interfacing via the RS232 Output (cont)

Example Printout (RS232, 24 character printer)

------------------------------------------------------------------------------------------------------------------------G L P O NG L P O NG L P O NG L P O NG L P O N23/11/93 10:35:5223/11/93 10:35:5223/11/93 10:35:5223/11/93 10:35:5223/11/93 10:35:52ID NUMBER 09ID NUMBER 09ID NUMBER 09ID NUMBER 09ID NUMBER 09MODEL M450MODEL M450MODEL M450MODEL M450MODEL M450ELECTRODE ID..........ELECTRODE ID..........ELECTRODE ID..........ELECTRODE ID..........ELECTRODE ID..........CHANNEL ACHANNEL ACHANNEL ACHANNEL ACHANNEL ATEMP COMP MTCTEMP COMP MTCTEMP COMP MTCTEMP COMP MTCTEMP COMP MTCCAL 1 25.0CAL 1 25.0CAL 1 25.0CAL 1 25.0CAL 1 25.0° C 7.000pHC 7.000pHC 7.000pHC 7.000pHC 7.000pH

OFFSET –5.8mVOFFSET –5.8mVOFFSET –5.8mVOFFSET –5.8mVOFFSET –5.8mV------------------------------------------------------------------------------------------------------------------------N A M EN A M EN A M EN A M EN A M E........................................................................................................................

GLP OFFGLP OFFGLP OFFGLP OFFGLP OFF

S/N 1 10:41 23/11/93S/N 1 10:41 23/11/93S/N 1 10:41 23/11/93S/N 1 10:41 23/11/93S/N 1 10:41 23/11/93A 7.554 pH 25.0A 7.554 pH 25.0A 7.554 pH 25.0A 7.554 pH 25.0A 7.554 pH 25.0° C M T CC M T CC M T CC M T CC M T CM E / PM E / PM E / PM E / PM E / PB 0.98E–4mmol/L 25.0B 0.98E–4mmol/L 25.0B 0.98E–4mmol/L 25.0B 0.98E–4mmol/L 25.0B 0.98E–4mmol/L 25.0° CCCCC

M T CM T CM T CM T CM T CM E/P NH3-M E/P NH3-M E/P NH3-M E/P NH3-M E/P NH3-

GLP function selectedDate and timeID number (user enterable)pH meter model numberElectrode ID (e.g. serial number)Measurement channel identifierTemperature mode (manual)Cal point, temperature and result

Electrode offset

Authorization

GLP function deselected

Sample number, time and dateChannel, result, temperature and temp. modeEndpoint method (manual)Channel, result, temperature and temp. modeEndpoint method (manual), and electrode type2

19109120-1 Rev. A, 11/96

2.8 Interfacing via the RS232 Output (cont)

To move around the software menu easily you can use thenumeric keypad as quick access keys. See Section 1.4 for a menuoverview, and the relevant ‘quick keys’. The 450 can also becontrolled by a PC with terminal software.To turn on the remote function send: TONTo return to a known position in the software menu send: S (forstandby) H (for home). This returns the 450 to pH mode, channelA measurement only.To turn the remote function off send: XNOTE Allow a 1 second delay between sending characters.

RS232 Keyboard Definitions

Key RS232 Key RS232 Key RS232Command Command Command

M

P

A

S

C

R

E

U

D

<

>

1

2

3

4

5

6

7

8

9

0

–

mode

on/off

prog

enter

autoread

cal

read

<<

<

<

2

3

1

4

5

6

7

8

9

0

-

2

20 109120-1 Rev. A, 11/96

3.1 Calibration Menu

This menu allows you to set 5calibration points for pH orconcentration; recall the time anddate of the last calibration and setthe isopotential point for pH.Default refers to the factory settingwhich the 450 uses if noinformation is entered.

3.1.1 Calibration point setting

Press or when the cal points sub routine ishighlighted.

If you enter the cal points sub routine from pH mode, the calpoints for pH calibration are set up. If you enter fromconcentration mode, the concentration calibration points are setup, and the standard set as the first calibration point is theisopotential 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

# appears if you set a pH calibration value to a standard buffer.The 450 stores temperature corrected values for the standardbuffers (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

enter

<

< <

enter

enter

enter

< <

calibration

cal points

last cal

iso

3

21109120-1 Rev. A, 11/96

3.1.1 Calibration point setting (cont)

press or to leave the sub routine without any furtherchanges.


3.1.2 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 3.3.1.)

press or to leave the sub routine.


3.1.3 Isopotential point setting (pH)

The default isopotential point is pH7.00 (0.00mV). See Section 4for further information.

Press or when iso sub routine is highlighted.

Press the display flashes showing that the value can bechanged.

Enter the required value using the keypad and press


3.1 Calibration Menu (cont)

< prog

read

enter

<

read

< prog

read

enter

<

enter

enter 3

22 109120-1 Rev. A, 11/96

display

channel

conc units

pH resolution

3.2 Display Menu

This menu allows you to selectmeasurement channel A, B or A &B; select the units of measurementfor concentration and change thedisplay resolution for pH mode.Default refers to the factorysetting, which the 450 uses if noinformation is entered.

3.2.1 Channels to display

The default selection is channel A only.

Press or when the channel sub routine ishighlighted.

Use and to select the measurement channel(s) you

want to use and press


3.2.2 Units for concentration to display

The default setting is no units (blank) selected. The unitsavailable are ppm, mmol/L, % and M. eq.

Press or when the conc units sub routine ishighlighted.

Use and to select the units of measurement you want

to use and press


NOTE Calibrate the 450 in the units you want to use forsample measurement. Changing the units does notchange the reading; for example, the 450 will not convertfrom ppm to mmol/L.

enter

<< <

enter

read

enter

<

< <

enter

read3

23109120-1 Rev. A, 11/96

3.2 Display Menu (cont)

3.2.3 Resolution for pH to display

The default setting is maximum resolution.

Press or when the pH resolution sub routine ishighlighted.

Use and to select the resolution you want to use and

press


enter

enter

<

< <

read

3

24 109120-1 Rev. A, 11/96

3.3 System Menu

This menu allows you to set thetime and date; set the language forthe display; set the baud rate fordata output and turn the key pressbeeper on or off. Default refers tothe factory setting, which the 450uses if no information is entered.

3.3.1 Time and date

Press or when the time/date sub routine ishighlighted.

Use and to select the time display, or one of the dateoptions.

Press the display flashes showing that the value can bechanged.

Enter the time or date using the keypad and and press

For example, to enter 4/12/96:

press


3.3.2 Language

Default language is English.

Press or when language sub routine is highlighted.

Use and to select the language you want to use andpress There will be a short delay while

the 450 initializes the language.


system

time/date

language

baud

beeper

enter

<

< <

enter

enter

<

0 4 2 9 6

< <

enter

read

enter

enter

<

< <

read

31

25109120-1 Rev. A, 11/96

3.3 System Menu (cont)

3.3.3 Baud rate

Default baud rate for the DATA socket is 1200. The other optionsavailable are 300, 4800, 7200, 9600. (See Section 2.8 for furtherinformation 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


3.3.4 Beeper on/off

A ‘beep’ accompanies valid key presses. This routine allows youto turn the beeper off. Default setting is beeper on.

Press or when the beeper sub routine ishighlighted.

Use and to select beeper on or off and press


enter

enter

enter

enter

<

< <

read

read

< <

<

3

26 109120-1 Rev. A, 11/96

3.4 Temperature Menu

This menu allows you to select thetype of temperature probe youwant to use (standard ATC orPT1000), or to enter thetemperature of solutions manually.Default refers to the factorysetting, which the 450 uses if noinformation is entered.

3.4.1 Temperature probe selection

Default probe is ATC.

Press or when the ATC type sub routine ishighlighted.

Use and to select which mode you want to use and

press␣


3.4.2 Manual temperature set

Default temperature is 25°C.

Press or when the manual sub routine ishighlighted.

Press the display flashes showing that the temperaturecan be changed.

Enter the required temperature using the keypad and press


NOTE Temperature can be entered manually when atemperature probe is connected, but the 450 will use thetemperature probe value.

enter

enter

enter

enter

enter

<< <

read

read

<

temptemp mode

ATC type

manual

3

27109120-1 Rev. A, 11/96

3.5 Limits Menu

This menu allows you to set highand low limits to monitor samplemeasurement in pH mode, andalso for temperature readings. Thealarm (to alert you to ‘out of limits’readings) can be set to show ondisplay only, to ‘beep’ and show ondisplay, or it can be turned off. Thelimits for pH are available at theDATA socket. Default refers to thefactory setting, which the 450 usesif no information is entered.

3.5.1 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


3.5.2 Set high/low limits for pH

Press or when the set limits sub routine ishighlighted.

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 19.999 and low–1.999.

enter

enter

<< <

read

limits

alarm

set limits

temp

enter

enter

enter

<

< < 3

28 109120-1 Rev. A, 11/96

3.5 Limits Menu (cont)

3.5.2 Set high/low limits for pH (cont)

Repeat for other limit.


The high/low limits for pH are available at the DATA socket. SeeSection 2.8 for further information.

3.5.3 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 130.0 and low–30.0.

Repeat for other limit.


enter

enter

enter

<

< <

read

read

3

29109120-1 Rev. A, 11/96

datalog

on/off

timer

recall data

clear data

3.6 Datalog Menu

This menu allows you to set uptimed measurements and print, orprint and log, the last 100 results.The data can be recalled to thedisplay, or to an external printer.The timer must be used with thedatalog function. Default refers tothe factory setting, which the 450uses if no information is entered.

3.6.1 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


NOTE You can use the on/off function to temporarily stop datalogging, without cancelling the timer and other options.Reselect an ‘on’ option to restart data logging.

3.6.2 Timer setting

Press or when the timer sub routine is highlighted.

Press the display flashes showing that the interval can bechanged.

Enter the timer interval using the keypad and andpress

For example, to enter 1 hour 30 minutes 30 seconds:

press

enter

enter

enter

enter

enter

<

<

< <

read

<

0 1 3 0 3 0

< <

enter

3

30 109120-1 Rev. A, 11/96

3.6 Datalog Menu (cont)

3.6.2 Timer setting (cont)


starts and stops data logging.

NOTES Use the following checklist to make sure you have setdatalogging up correctly:

check manual endpoint facility is selected, notautomatic (see Section 2.4).

check 'datalogging on' is selected (print only or store& print - see Section 3.6.1).

check a timer interval is entered (Section 3.6.2).

check the decimal point is flashing (i.e. the 450 ismeasuring) when you return to measurement mode.

If it is not press to start the measurementsequence.

You can change mode, or channel, or other variableswhile using the timer facility. The sample number willrestart at␣ 1.

The 450 can log up to 100 results. After 100 results the450 starts to overwrite the first results logged. So, if forexample 150 measurements have been made, the 450will retain the data for results 51 to 150.

3.6.3 Recall logged data

Press or when the recall data sub routine ishighlighted.

Use and to select recall option and press

If you recall the data to the external printer, it will print all thedata logged (up to 100 results).

read

read

enter

enter

<

< <3

read

31109120-1 Rev. A, 11/96

3.6.3 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 If you have changed mode, or channel, duringmeasurement there will be more than one sample

number 1, etc. Press twice to see other samples

with the same number.

Press to leave the sub routine.

3.6.4 Clearing logged data

Press or when the clear data sub routine ishighlighted.

To clear all the data held in memory press

To leave the routine without clearing data press

3.6 Datalog Menu (cont)

enter

enter

<

<

< <enter enter

enter

<

3

32 109120-1 Rev. A, 11/96

3.7 GLP (Good Laboratory Practice) Menu

This menu allows you to set up thegood laboratory practice (GLP)function. The␣ 450 can be set toforce calibration after a presettime interval, after a presetnumber of samples, or both. Theprintout shows all the calibrationinformation. If using bothmeasurement channels (A and B)the GLP function applies to bothchannels - the channels cannot beset up individually. Default refersto the factory setting, which the450 uses if no information isentered.

3.7.1 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


3.7.2 Calibration alarm setting

Press or when the cal alarm sub routine ishighlighted.

Use and to select time interval or number ofsamples.

Press the display flashes showing that the value can bechanged. The time interval can be set between1 second and 23 hours 59 minutes and 59 seconds;the number of samples can be set between 0 and 99.

GLP

on/off

cal alarm

ID no.

enter

enter

enter

enter

<

<

< <

< <

read

3

33109120-1 Rev. A, 11/96

3.7 GLP Menu (cont)

3.7.2 Calibration alarm setting (cont)

Enter the required value using the keypad and press


After the time interval has elapsed, or the number of sampleshave been measured, a message will appear on the 450 displayrequesting calibration. The 450 will not allow further samplemeasurement until a calibration has been carried out.

3.7.3 Entering an ID number

Press or when the ID no. sub routine is highlighted.

Press the display flashes showing that the number can bechanged.

Enter the required ID number (e.g. operator ID or meter serial

number) using the keypad and press

Up to eight digits can be entered.


The ID number is printed with the calibration information.

enter

enter

enter

enter

<

read

read

3

34 109120-1 Rev. A, 11/96

3.8 Diagnostics Menu

This menu allows you to request aself test - the 450 will test thekeyboard controls, ROM, display,RS232 and RAM. You can alsoreset all variable information tothe default values. Default refersto the factory setting, which the450 uses if no information isentered.

3.8.1 Meter self test

Press or when the self test sub routine ishighlighted.

Press to enter the self test.

The 450 displays the keyboard test. Press each control and checkthat the highlighting on the display goes off. When all thecontrols have been checked the 450 will test the ROM (read onlymemory) 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 DATAsocket (RS232)

0 1 2 3 4 5 6 7 8 9 A B C D E F G H I J K L M N

check the printout on the external printer.

The 450 finally tests the RAM (random access memory). Therewill 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 return directlyto measurement.

read

enter

enter

<

diagnostics

self test

reset

3

35109120-1 Rev. A, 11/96

3.8 Diagnostics Menu (cont)

3.8.2 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, andreinitialize the display.

Press to leave the sub routine without resetting data.

enter

enter

<

<

3

36 109120-1 Rev. A, 11/96

4.1 Basic Theory

pH is the unit of measurement of the acidity or alkalinity of asolution, and is expressed as the negative logarithm of thehydrogen 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 areference electrode or a combination electrode (both electrodes inone body) are used along with a meter capable of displaying themeasurements.

The pH sensing electrode has an internal solution with a constantpH value, and develops a potential when placed in a solution. Thisis caused by the activity of the H+ ions in the solution. The referenceelectrode has a defined, stable potential irrespective of the H+

activity in the sample. The Model 450 measures and converts theresulting minute electrode voltages into a pH reading.

The response of a pH electrode (or its slope) is defined by theNernst equation:

Electrode response = E0 – 2.3RT . pH nF

where: E0 = a constant factor T = the temperature (Kelvin)R = the gas constant n = the ionic chargeF = the Faraday constant

The theoretical slope for an electrode is 59.16 mV where the H+

ionic charge (n) = 1 at 25°C (298K). This means that for a oneunit change in pH the system will sense a change of 59.16 mV.The measurement of electrode slope is a good indication ofelectrode condition.

Temperature is also an important consideration when measuringpH. It affects the electrode slope. ATC probes are recommendedso that the slope can be corrected for temperature. There aremany other factors that affect pH.

Further information on pH theory and the factors that affect theability to do accurate pH readings is included in ‘Guide to pHMeasurement’.

4

37109120-1 Rev. A, 11/96

4.2 Operating Hints

This section gives some brief operating hints and good laboratorypractices 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 4.0buffer for several hours prior to their use. Make sure that thewetting cap has been removed from the tip of the electrode.

2. Always remove the wetting cap and fill hole plug duringcalibration and measurements. Replace the fill hole plugwhen done.

3. Calibrate the electrode daily. Though a one pointcalibration may be suitable for some applications, werecommend that a two point calibration (that brackets theexpected pH range) be performed.

4. Be aware that if you are measuring hot or cold sampleswithout the use of an ATC probe, the values displayed arenot accurate. You should be calibrating and measuring atroom temperature.

5. When transferring from one sample to another, alwaysrinse the electrode with distilled water and blot dry. Handlethe electrode carefully and do not use it as a stirring rod.

6. Do not use calibration buffers after the expiration dateprinted on the package. Keep the bottles tightly capped andstored according to the manufacturer's instructions. Neverput used buffer back into the bottle of new buffer.

7. For small sample volumes, make sure that both the pH bulband the reference junction are in contact with the sample.

8. Response time is a function of both the electrode and thesolution. Some solutions have very fast response whileothers, particularly those with low ionic strength, may takeseveral minutes.

9. Samples must be in solution (water). You cannot measurethe pH of a dry sample.

Refer to the electrode manufacturer's instructions for properelectrode care and maintenance. See Section 4.3.2 for generalelectrode maintenance and Section 4.4.3 for problem solving.

4

38 109120-1 Rev. A, 11/96

4.3 Maintenance

4.3.1 Meter Maintenance

The Model 450 Meter needs no maintenance except for anoccasional wipe with a damp cloth. The front panel is made ofpolyester and is not affected by most solvents. Polyester is knownto be affected by some organic solvents, including toluene, xyleneand methyl-ethyl-ketone. It is good laboratory practice to wipeaway any spills as soon as they occur.

4.3.2 Electrode Maintenance

CAUTION Solutions used to clean electrodes must be handledwith the care accorded to toxic or corrosivesubstances.

• Do not allow the reference chamber of the electrode to dryout. Always keep it filled with the proper fill solution.

• Formation of KCl salt at the tip and side of the electrode isnormal and should be rinsed off with warm water.

• Leave the tip of the electrode in an inch (25 mm) of pH 7.0or 4.0 buffer when it is not being used. Do not leave it indistilled water. For long term storage follow the electrodemanufacturer's instructions.

• If the electrode slope is off or the electrode response hasbecome sluggish or inaccurate, change the fill solution. Ifthat does not improve the response then the pH sensingglass and the junction have probably become coated withsome 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 15minutes. A proper flowing junction should have KCl saltcrystals forming on it. If none appear, review the followingsuggestions for cleaning.

Protein contamination - soak the tip of the electrode for1-2 hours in a solution of 10% Pepsin and water withenough Hydrochloric acid added to bring the pH of thesolution to 1.0. Rinse the electrode and soak in pH 7.0buffer until stable.

4

39109120-1 Rev. A, 11/96

4.3 Maintenance (cont)

4.3.2 Electrode Maintenance (cont)

Oil contamination - Carefully clean the tip of theelectrode using a cotton swab soaked with alcohol oracetone. The tip of Glass body electrodes can be putdirectly into organic cleaners but do not put plastic orepoxy body electrodes into organic solvents. Rinse theelectrode and soak in pH 7.0 buffer until stable.

All others - Soak tip of the electrode in 0.1 MHydrochloric acid for one hour. Rinse the electrode andsoak in pH 7.0 buffer until stable.

4.4 Problem Solving

Most problems are caused by electrode faults rather than by theModel 450 but power fluctuations can corrupt calibration valuesbeing held in the meter memory.

4.4.1 Meter TestTo assure that the meter memory and calibration points have notbeen corrupted by power fluctuations, perform the Meter Test asfollows:

1. Press or when the self test sub routine ishighlighted, see Section 3.8.1.

The 450 tests the ROM and RAM, and allows the keyboardcontrols, RS232 output and display to be checked.

2. Disconnect the electrode from the pH socket, and connectthe shorting clip (or shorting plug). Select mV mode. The450 displays 0 ±4 mV. Disconnect the shorting clip (orshorting plug), and the reading changes. Test bothchannels.

3. Disconnect the temperature probe – the display showsMTC. Reconnect the temperature probe (or electrodeincorporating ATC); the display shows ATC or PT1000 andthe ambient temperature.

4. Reconnect electrode.

enter

<

4

40 109120-1 Rev. A, 11/96

4.4 Problem Solving (cont)

4.4.1 Meter Test (cont)

If the meter passes the above test the problem is electroderelated. Refer to Section 4.4.3 for electrode troubleshooting.

If the meter fails the above test call the number on the back ofthis manual for warranty and service information.

4.4.2 Meter Error Codes

Error codes are designed to give the user information onelectrode performance problems.

E1 pH Electrode is not reading a value close enoughto the first calibration buffer. Electrode needsmaintenance (see Section 4.4.3).

E2 pH Electrode is not giving a value within 0.5 pH ofthe second calibration buffer. Electrode needsmaintenance.

Ion Selective Electrode is not giving sufficientchange between calibration points. Change mustbe at least 15 mV but not more than 90 mV. Checkcalibration standards and electrode.

E3 Temperature of pH buffer outside limits of 0° to50°C. Check manually entered temperature orreplace ATC probe.

E4 Calibration points must have different values.Check cal point settings (see Section 3.1.1).

E5 pH buffer is outside range of 0 to 14. Check calpoint settings.

E6 Illegal date or time entered (see Section 3.3.1).

Measurement is out of range of the display. Themeter would display dashes if the electrode were notin a solution, the pH of the solution is not between-1.999 and 19.999 or if the fill solution in theelectrode is low or wrong. Dashes in the temperaturemode indicates that the ATC has failed.

Illegal limit Limit entered is outside range. Check value.

4

41109120-1 Rev. A, 11/96


4.4.2 Meter Error Codes (cont)

Slope is a value that compares the actual slope determined bythe calibration to the theoretical slope defined by the Nernstequation. This value is displayed as a percent of theoretical andis called electrode efficiency (see Section 4.1 for Basic Theory).Generally the slope value can be interpreted as follows:

95 - 100% Everything is probably working fine.90 - 95% Electrode needs maintenance. Fresh fill solution

and general cleaning.85 - 90% 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 detailson maintenance, cleaning and reconditioning electrodes.

4.4.3 Electrode Problem Solving

Slow response or unstable readings in calibration buffers isusually related to the condition of the reference fill solution or itsflow through the junction.

1. The fill solution acts as an electrical conductor between thereference inside the electrode and the solution under test.Empty the electrode and refill with fresh fill solutionregularly.

2. The junction is designed to allow the fill solution to leakout of the tip of the electrode at a slow controlled rate. Totest for proper flow, rinse the tip of the electrode, blot dryand let the electrode hang in the open air for 15 minutes. Ifit is flowing properly, salt crystals of the fill solution willform on the junction. If they do not, refer to themanufacturer's instructions for junction cleaning orreplacement.

4

42 109120-1 Rev. A, 11/96


4.4.3 Electrode Problem Solving (cont)

Slow response or unstable readings in samples can be caused bya number of things. Those listed below assume that everythingwas fine in the calibration buffers.

1. Low ionic strength samples will tend to be very drifty. Youare trying to take an electrical measurement in a solutionthat is a very poor conductor. Try adding a drop of KCl fillsolution to about 5 mL of the sample. In most cases it willnot change the pH but will give the sample enough ionicstrength for the electrode to finish the reading.

2. Non aqueous samples (organics) do not follow the normalpH scale and can cause some measuring problems. Thesesolutions are usually low in ionic strength, may dehydratethe pH membrane and often cause the junction to plug dueto incompatibility with the electrode fill solution. The mostreliable way to pH organics is to dilute them with wateruntil stable readings can be generated.

3. Concentrated samples can cause pH measuring errors.This is caused by problems with the pH sensing glass andits ability to distinguish the Hydrogen ion activity over themass of other ions in the sample. The creation of newjunction potentials due to KCl dissociation problems canalso cause instability. The best solution is to dilute thesamples into measurable ranges.

For more information refer to the Corning Guide to pHMeasurement.

Information on ISE electrodes can be found in the Corning Guideto ISE Measurement.

4

43109120-1 Rev. A, 11/96

4.5 Meter Specifications

Operating RangespH –1.999 to 19.999mV ±1999.9Rel. mV ±1999.9Temp. –30 to 130°CConc. 0.0001 to 19999

ResolutionpH 0.001 / 0.01 / 0.1mV 0.1Rel. mV 0.1Temp. 0.1°C

Relative Accuracy*pH ±0.001mV ±0.2Rel. mV ±0.2Temp.

NTC -30 - 0°C ±1%0 - 50°C ±0.5°C50 - 130°C ±1%

PT1000 -30 - 0°C ±0.4°C0 - 100°C ±0.2°C100 - 130°C ±0.4°C

Conc. ±0.5%* ±1 least significant digit

Time0 to 23 hours 59 minutes

TimerUser selectable0 seconds to 11 hours 59 mins59 secs

Memory100 memories

Isopotential Point7.000 pH, user adjustable

pH Calibration5 point

Temperature Compensation–5 to 105°C, automatic andmanual

DisplayDot matrix LCD display

OutputsRS232Recorder (Channel A only)Karl Fischer

Input ConditionsImpedance greater than 1012 ohms

Operating ConditionsOperating temperature: 5 to 40°COperating humidity: max 80% at35°C (non condensing)Installation category 2Pollution category degree 2

Size / Weight10 x 8 x 4 inches (255 x 200 x95 mm) / 2.9 lbs (1.3 kg)

Power RequirementsThe 450 is supplied with anappropriate power supply unit, e.g.USA/Japan 100V - 120V

50/60Hz, 9VAEurope 230V 50Hz, 9.7VAOutput from PSU 9V DCNOTE The 450 should only be

used with the powersupply unit provided.

450 Power Rating 4.5VA

4

44 109120-1 Rev. A, 11/96

4.5 Meter Specifications (cont)

Regulatory ComplianceThe 450 is manufactured in a FDA (Food & DrugAdministration) and ISO 9001 approved plant for Corning, andcomplies with the following regulatory standards: UL1262,CSA151, IEC1010. The 450 also complies with the EuropeanEMC Directives and therefore carries the CE mark.

Environmental ComplianceThe casework components of the 450 are marked with theappropriate recycling identification symbol. The packaging ismanufactured using recycled cardboard, and printed with waterbased ink. The packaging is recyclable. The manual is printed onenvironmentally friendly paper.

4

Consumables and Accessories

Catalog # Description Quantity

477968 Automatic Temperature Probe - Basic 1477969 Automatic Temperature Probe - PT1000 1477389 Disposable Meter Cover 5478109 Electrode Arm Assembly 1477006 Electrode Fill Solution 3M KCl (125 mL) 6 bottles477965 Electrode Storage Container 3478353 Electrode Conditioning Solution (30 mL) 3 bottles477989 Guide to pH Measurement 1477959 Guide to ISE Measurement 1476436 pH Combination Electrode, ‘3 in 1’ Refillable 1476466 pH Combination Electrode, ‘3 in 1’ Gel 1476146 pH Combination Electrode, Hi-Performance 1478540 pH 4.00 Buffer (500 mL) 2 bottles478570 pH 7.00 Buffer (500 mL) 2 bottles478510 pH 10.01 Buffer (500 mL) 2 bottles473651 pH 4.00 Buffer Sachets 30 packs473650 pH 7.00 Buffer Sachets 30 packs473652 pH 10.01 Buffer Sachets 30 packs473676 pH Buffer Multi-Pack Sachets 32 packs473653 pH Electrode Rinse Sachets 30 packs471226 Power Supply, 100/120V - 50/60Hz 1471228 Power Supply, 230V - 50Hz 1477788 RS232C Cable 1470109 Shorting Test Clip 3470493 Dot Matrix Printer with Cables 1

Warranty:Corning warrants this product to be free from defects in materials and workmanship. Thewarranty period for the meter is two (2) years from the date of purchase and the probe issix (6) months from the date of purchase.

THIS WARRANTY IS MADE IN LIEU OF ALL OTHER WARRANTIES EXPRESSED ORIMPLIED INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FORA PARTICULAR PURPOSE. CORNING SHALL NOT BE LIABLE FOR ANY LOSS ORDAMAGES ARISING FROM THE USE OF THESE PRODUCTS NOR FORCONSEQUENTIAL DAMAGES OF ANY KIND.

In the event that a meter or probe fails under normal laboratory conditions within thespecified period because of a defect in material or workmanship, Corning will, at itsoption, repair or replace the product. Contact Corning Customer Service for returnauthorization and shipping instructions at 1-800-222-7740.

© 1992. All rights reserved.

Corning Incorporated

Science Products Division

Corning, New York 14831

USA

Telephone: 1-800-222-7740 (US and Canada)

1-607-974-0353 (Outside US)

Fax: 1-607-974-0345

430 ? Rev. A, 6/96

Documents

450 pH/ion Meter Instruction Manual - Cole-Parmer · Instruction Manual This manual contains ... likely to cause interference in which case the user at his own expense ... For example,