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Page 43

19.3  pH Temperature Compensation 

 

The  slope  of  a  pH  electrode  (section 

Error!  Reference  source  not 

found.

) is affected by temperature. This effect is compensated for either 

by  using  an  Automatic  Temperature  Compensation  (ATC)  probe  or  by 
entering the sample temperature manually. 

Figure 19-3

 shows the slope of 

a pH electrode at various temperatures. 

-600

-400

-200

0

200

400

600

0

7

14

m

V

Electrode
Potential (mV) at
0 oC (54mV/pH)

Electrode
Potential (mV) at
50 oC (64mV/pH)

Electrode
Potential (mV) at
100 oC
(74mV/pH)

pH Electrode Response, as a Function of Temperature

pH

 

Figure 19-3 

 
 

 
 
 
 
 
 
 
 
 
 
 
 
 
 

Summary of Contents for WP-80D

Page 1: ...ons have also been included to enable you to find the information you need at a glance 2 Introduction The introduction has a diagram and explanation of the display and controls of the WP 80D It also contains a full listing of all of the items that you should have received with your WP 80D Please take the time to read this section as it explains some of items that are mentioned in subsequent sectio...

Page 2: ...ty Ltd ABN 30 009 773 371 4 Jamberoo Street Springwood Brisbane Australia 4127 Phone 07 32 900 400 International 61 7 32 900 400 Fax 07 3808 4871 International 61 7 3808 4871 Email tps tps com au Web www tps com au ...

Page 3: ... 19 7 4 Manual Temperature Setting 19 8 Good Laboratory Practices GLP 20 8 1 To recall GLP information on the display 20 8 2 Failed Calibration 21 8 3 Printing GLP Information to the RS232 Port 21 8 4 Instrument Serial Number 22 8 5 Additional GLP Features 22 9 Notepad Function 23 9 1 Recording Readings into the Notepad 23 9 2 Recalling Records from the Notepad 23 9 3 Erasing Records from the Note...

Page 4: ...ing the Clock 35 15 Selecting Buffers for Auto Buffer Recognition 36 16 Initialising the WP 80 37 17 Instrument firmware version number 37 18 Troubleshooting 38 18 1 General Errors 38 18 2 pH and mV ORP Troubleshooting 39 18 3 Temperature Troubleshooting 40 19 Appendices pH Sensor Theory 41 19 1 Asymmetry of a pH Sensor 41 19 2 Slope of a pH Sensor 42 19 3 pH Temperature Compensation 43 20 Warrant...

Page 5: ...Page 5 1 Introduction 1 1 WP 80D Display and Controls ...

Page 6: ... selected See section 6 Press to access the user friendly menu system which makes the WP 80D a breeze to operate and The and keys are used when calibrating temperature readout section 7 setting manual temperature compensation section 7 4 setting the clock section 14 1 setting the automatic logging period section 10 and displaying GLP information section 8 1 The key is also used to initialise the W...

Page 7: ... Buffer 200mL 121381 6 Right angle BNC adapter JSBNCR 7 Battery charger 130037 8 Manual Options that may have been ordered with your WP 80D 1 Extended cable 130040 2 RS232 Serial Interface Cable 130041 3 Communication software for Windows 95 and later 130086 4 USB to Serial Adaptor requires 130041 also 130087 5 Hard Carry Case 130059 6 Battery charger lead for 12V cigarette lighter socket 130046 7...

Page 8: ...uracy 0 2 o C General Specifications Temperature Compensation pH only not for mV ORP Automatic 0 to 100 o C Manual 0 to 100 o C Calibration pH Auto Standard Recognition in pH4 01 pH6 86 pH7 00 pH9 18 or pH10 01 buffers pH Sensor Asymmetry Range 1 00 to 1 00 pH pH Sensor Slope Range 85 0 to 105 Input Impedance 3 x 1012 Ω mV ORP Sensor calibration not available Temperature Use a reference thermomete...

Page 9: ... port but is not displayed Battery Saver On Auto switch off after 5 minutes Off Continuous use Bar Graph display of battery charge level Readout of battery voltage available for troubleshooting Good Laboratory Practices Date Time and Value of last pH and Temperature calibration are stored and can be recalled or sent to the RS232 port at any time Power 6V NiMH Rechargeable Battery for approx 50 hou...

Page 10: ...ailable when Channel 1 in pH mode F2 pH2 available when Channel 2 in pH mode F3 Temp F2 Notepad F1 Recall F2 Erase F3 Print F4 Prog F1 Min F2 Sec F3 Hr Set Period F3 Mode F1 Chan1 F1 pH F2 mV ORP F3 Rel mV ORP F3 Mode F2 Chan2 F1 pH F2 mV ORP F3 Rel mV ORP F4 Setup F1 Batt F1 OFF Battery Saver F2 ON Battery Saver F2 Clock F3 GLP F1 Recall F3 Print F4 Baud F1 300 F2 1200 F3 9600 F4 19200 ...

Page 11: ...de Press to select Relative mV ORP mode Press to turn that channel off Press to quit and retain the current selection 3 The WP 80D will now display the selected modes along with Temperature and the Time eg 7 00pH 500 0m 25 0 12 00 00 Notes 1 If Channel 1 is set to Relative mV ORP then Temperature is NOT displayed 2 Temperature compensation does not apply in mV ORP mode 3 If the temperature sensor ...

Page 12: ...e 12 5 The decimal point is replaced by a if a pH or Temperature calibration has failed sections 4 1 and 0 if the unit is initialised section 16 or if the unit has lost its factory calibration section 18 1 ...

Page 13: ... detailed explanation 4 Select pH Mode Either F3 Mode F1 Chan1 F1 pH or F3 Mode F2 Chan2 F1 pH 5 Ensure that temperature has already been calibrated or manually set see sections 7 1 and 7 4 NOTE If the decimal point in the temperature reading is shown by a then the temperature readout is not calibrated 6 Remove the wetting cap from the pH sensor 7 Rinse the pH and Temperature sensors in distilled ...

Page 14: ...eference junction are both covered as per the diagram in step 8 above DO NOT place the electrodes directly into the buffer bottle pH9 18 and pH10 01 buffers are unstable once the bottles have been opened Discard immediately after use 13 Select pH Calibration for the same channel as calibrated in step 9 Either F1 Cal F1 pH1 or F1 Cal F2 pH2 14 When the reading has stabilised press the key to calibr...

Page 15: ...ffer value displayed corresponds to the buffer that you are using 4 3 Calibration Messages 1 If a 1 point calibration has been successfully performed the WP 80D will display the following message and the asymmetry of the electrode For example 1 Point Cal OK Asy 0 10pH 2 If a 1 point calibration has failed the WP 80D will display the following message and the failed asymmetry value of the electrode...

Page 16: ...emperature sensor does not need to be connected 2 Switch the meter on 3 Select Relative mV ORP Mode Either F3 Mode F1 Chan1 F3 Rel mV ORP or F3 Mode F2 Chan2 F3 Rel mV ORP 4 The display should now be showing Relative mV ORP on the top line with absolute mV ORP or date and time on the bottom line For example 500 0R 7 00pH 660 F4 Zeros 500 0R 7 00pH 31 12 12 00 00 Press to alternate between absolute...

Page 17: ...and is ready for use The readout can be re zeroed by pressing the key whenever required 6 1 Notes 1 If Relative mV ORP is selected for BOTH channels then the WP 80D offers you a choice between Channel 1 or Channel 2 when you press the key to zero the Relative mV ORP reading Select Channel F1 Chan1 F2 Chan2 2 The Relative mV ORP offset is retained in memory when the WP 80D is switched off even when...

Page 18: ...3 Temp 5 The reading from the probe is now displayed on the right of the display and the value you are going to set is shown on the left For example 25 0 20 0 Set F1 Cal 6 When the reading on the right has stabilised press the and keys until the reading on the left shows the same temperature as the mercury thermometer 7 Press the key to calibrate the temperature readout Alternatively press the key...

Page 19: ...ual Temperature Setting If the temperature sensor is not connected the temperature of the sample solution must be set manually for accurate pH measurements A separate thermometer will be required for this 1 Switch the meter on 2 Measure the temperature of the sample 3 Select Temperature Calibration F1 Cal F3 Temp 4 The current temperature setting is now displayed For example 25 0 Man Temp Set F1 S...

Page 20: ...instrument model firmware version number and instrument serial number are displayed along with a prompt describing how to scroll through the GLP information For example WP80D V2 0 S1234 More Back 5 Press the key to sequentially scroll through the GLP information for all parameters Press the key to scroll back to previous data The sequence of information displayed is shown below Press to abort at a...

Page 21: ...the RS232 port 1 Switch the meter on 2 Ensure that the WP 80D RS232 cable is connected to the instrument and to the printer or PC 3 Send the GLP information to the RS232 port F4 Setup F3 GLP F3 Print 4 The GLP information is sent to the RS232 port in formatted ASCII text For example WP80D V2 0 S1234 31 12 10 12 00 pH1 Asy 0 00pH 31 12 10 11 40 pH1 Slope 100 0 31 12 10 11 45 pH2 Asy 0 00pH 31 12 10...

Page 22: ...Dual pH mV ORP Temp where S1234 is the serial number The serial number is displayed when recalling the GLP information section 8 1 The serial number is included on the printout of GLP information section 8 3 8 5 Additional GLP Features Another GLP requirement is to record the date and time of every reading The WP 80D does this for you when readings are recorded either with the Notepad function sec...

Page 23: ...n as required The maximum number of readings that can be stored in the Notepad is 3600 9 2 Recalling Records from the Notepad To recall records from the Notepad onto the WP 80D display 1 Select the Notepad menu F2 Notepad 2 Select F1 Recall from the menu 3 Record number 1 is now displayed for example 7 00pH 500 0 1 F2 Clk 4 Press to alternatively display the date and time or the data for this reco...

Page 24: ... Charger RS232 socket of the WP 80D The charger optional solar panel or optional car battery lead can be connected into the spare socket on the cable for long term use if required 2 Connect the other end of the RS232 cable to an RS232 Printer or to COM1 or COM2 of a PC 3 Ensure that the baud rate for the printer or PC and the WP 80D are the same If necessary alter the baud rate of the WP 80D see s...

Page 25: ...has been correctly set select whether this period is in minutes seconds or hours Press to save the period as minutes Press to save the period as seconds Press to save the period as hours eg If the period was set to 05 followed by then the WP 80D will automatically log a record every 5 seconds 5 The WP 80D will ask if the records are to be logged into the Notepad or sent directly to the RS232 port ...

Page 26: ... The WP 80D will beep each time a record is sent to the RS232 port 8 Press to stop automatic logging Notes 1 The clock must be set before the WP 80D will allow automatic logging to start The message Clock Not Set is displayed if the clock is not set 2 The Battery Saver function section 12 is disabled while the meter is in Automatic Data logging mode to stop the meter switching off while logging da...

Page 27: ...ords can be sent directly to the RS232 port rather than stored in memory during automatic data logging See section 10 for details 11 3 RS232 Configuration The WP 80D RS232 configuration is 8 bits No Parity 1 Stop Bit XON XOFF Protocol 11 4 Communication and Statistical Software Communication between the WP 80D and a PC can be handled with any RS232 communication software A TPS communication softwa...

Page 28: ...ds with the message ENDS cr Erase logged data E cr Erases all logged records from the WP 80D memory Returns the message ERASED cr to confirm that the records have been erased Request status information S cr Returns the model name firmware version number instrument serial number and number of logged readings in memory eg WP80D V2 0 S1234 3600 cr where are spaces Note that the number of logged readi...

Page 29: ...tion which can be any of the following pH for pH readout mV for Millivolts readout mVR for Relative Millivolts readout TTTTTT is Temperature data 6 characters right justified uuu is the Temperature unit description which can be either of the following oC for real Temperature data oCm for manual Temperature compensation values dd mm yy is the date month and year data hh mm ss is the hours minutes a...

Page 30: ...ng the G command section 11 5 the computer must respond with a character after receiving each line For example WP80D V2 0 S1234 31 12 10 12 00 pH1 Asy 0 00pH 31 12 10 11 25 pH1 Slope 100 0 31 12 10 11 30 pH2 Asy 0 00pH 31 12 10 11 35 pH2 Slope 100 0 31 12 10 11 40 Temperature Offset 1 0oC 21 12 10 11 45 ENDS ...

Page 31: ...iles prn txt csv 3 Navigate to the folder where your data file is stored and double click it to start the Text Import Wizard Note The default data folder for the WinTPS software is C My Documents WinTPS 4 In step 1 of the Text Import Wizard select Fixed width as per the sample screen below then press Next Note that the data column headers in the first row appear only when the data is downloaded us...

Page 32: ...ss Next after the column breaks have been inserted 6 Simply press Finish at step 3 of the Text Import Wizard TPS recommends that the data format for each column be set once the data is in spreadsheet format For help on formatting the data columns charting graphing or other operations please consult the Microsoft Excel help file Alternatively please contact TPS and we will try to provide further as...

Page 33: ...e battery saver function for continuous use Press to enable the battery saver function The meter will switch itself off if no key has been pressed for five minutes Press to quit the battery saver menu and retain the current setting Notes 1 For troubleshooting purposes the battery volts can also be displayed in the battery saver menu Press to display battery volts 2 The symbol flashes when the batt...

Page 34: ...harge the battery 1 Plug the battery charger solar panel or car cigarette lighter adaptor into the Charger RS232 socket DO NOT plug into the Temperature socket as this will damage the WP 80D 2 Charge for approximately 8 hours for full capacity The WP 80D has special circuitry to prevent overcharging so the charger can be used continuously 3 To ensure optimum battery life and capacity the WP 80D sh...

Page 35: ... minutes Press the and keys until the minutes are correct 7 Check that the date and time are correct Press to save the settings If any changes are needed press the key to move left to the desired position Press to quit without resetting the clock Notes 1 The WP 80D does not test for a valid day of the month when setting the clock eg attempting to enter 31 02 10 is not corrected 2 The WP 80D does t...

Page 36: ...ect F1 7 00pH Buffer F2 6 86pH The arrow indicates the current selection 4 Press to select pH7 00 as the primary buffer Press to select pH6 86 as the primary buffer Press to quit buffer selection and retain the current setting 5 The display will now show the currently selected high pH buffer Select F1 9 18pH Buffer F2 10 0pH The arrow indicates the current selection 6 Press to select pH9 18 as the...

Page 37: ...itch the WP 80D off 2 Press and hold the key while switching the WP 80D back on 3 The following messages should be displayed Initialized MUST ReCalibrate then WP80Ds V2 0 S1234 Dual pH mV ORP Temp The s after WP 80D is shown when the RS232 serial port option is fitted 4 The meter then displays pH and Temperature Note that the decimal points have been replaced with a to indicate that the unit requi...

Page 38: ...ature see section 7 1 Flashing symbol Battery is below 5 60 volts Recharge the battery Note that the unit will switch itself off when the battery falls below 5 00 volts Meter displays the word OFF and switches off Battery is below 5 00 volts Recharge the battery If this fails check the charger If charger OK replace the battery Meter will not turn on Battery is exhausted Recharge the battery If thi...

Page 39: ...een set to automatically recognise see section 15 Clean glass bulb as per instructions supplied with the electrode Attempt rejuvenation as per instructions supplied with the electrode If not successful replace electrode Dry in a warm place Replace buffers Unstable readings 1 Electrolyte chamber needs to be refilled 2 Reference junction blocked 3 Glass bulb not clean 4 Bubble in glass bulb 5 Faulty...

Page 40: ...for all solutions Glass bulb or internal stem cracked Replace electrode Display flashes ATC and LIMIT The Temperature is not within the ATC limits Cool Heat solution before taking measurements 18 3 Temperature Troubleshooting Symptom Possible Causes Remedy Displays Man when temperature probe is plugged in 1 Faulty temperature probe Fit new temperature probe part number 121247 Temperature inaccurat...

Page 41: ...he reference junction A saturated solution of KCl is used to make contact with the sample It is vital that the KCl solution has an adequate flow rate in order to obtain stable accurate pH measurements 19 1 Asymmetry of a pH Sensor An ideal pH electrode produces 0 mV output at 7 00 pH In practice pH electrodes generally produce 0 mV output at slightly above or below 7 00 pH The amount of variance f...

Page 42: ...In practice pH electrodes usually produce slightly less than this The output of a pH electrode is expressed as a percentage of an ideal electrode For example an ideal electrode that produces 59mV pH unit has 100 Slope An electrode that produces 50 15mV pH unit has 85 Slope see Figure 19 2 600 400 200 0 200 400 600 0 7 14 mV 85 Slope at 25 oC 50 15mV pH 100 Slope at 25 oC 59mV pH Response of pH Ele...

Page 43: ...an Automatic Temperature Compensation ATC probe or by entering the sample temperature manually Figure 19 3 shows the slope of a pH electrode at various temperatures 600 400 200 0 200 400 600 0 7 14 mV Electrode Potential mV at 0 oC 54mV pH Electrode Potential mV at 50 oC 64mV pH Electrode Potential mV at 100 oC 74mV pH pH Electrode Response as a Function of Temperature pH Figure 19 3 ...

Page 44: ...orrect operation or from interpretation of information derived from the equipment Specifications are subject to change without notice This warranty becomes invalid if modifications or repairs are carried out on this unit by unauthorised persons There are no express or implied warranties which extend beyond the face hereof Procedure for Service Please read service details on our Service web page fi...

Page 45: ...d returned to you by express air freight where possible For instruments beyond warranty period a repair cost will be calculated from parts and labour costs and emailed to you If you decline to have the equipment repaired the complete instrument will be returned to you freight paid not serviced TPS Pty Ltd has only one service location which is located at our factory in Brisbane Service Department ...

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