Model 3540 Combined pH & Conductivity Meter Operating Manual Safety This is important information; please read carefully before installing or using this instrument. 1. The Model 3540 pH/Conductivity meter is only for operation by personnel who are trained and aware of the principles and applications involved in making electrochemical measurements. For further help and advice please contact your local distributor, e-mail sales@jenway.com or visit www.jenway.com 2.
Contents: Section 1 Section 2 Section 3 Section 4 Section 5 Section 6 Section 7 Section 8 Introduction Instrument description Display & controls Outputs Electrode Selection Good practice guidelines - pH Good Practice Guidelines – Conductivity 1.1 1.2 1.3 1.4 1.5 1.6 Getting Started Unpacking Installation 2.1 2.2 Set Up - General Instrument Set Up GLP Set Up Data Logging Set Up Time/Date Set Up 3.1 3.2 3.3 3.
Section 9 Section 10 Addendum Accessories and Spares Optional accessories Spares 9.1 9.2 Specification & Data Technical specification Analogue output RS232 serial interface Keypad emulation Printing Alarm Outputs 10.1 10.2 10.3 10.4 10.5 10.6 Buffer/Standard Vs Temperature Tables Jenway NIST DIN JIS Conductivity Ad.1 Ad.2 Ad.3 Ad.4 Ad.
Section 1 Introduction 1.1 Instrument Description The model 3540 pH/conductivity meter is a dual channel, dual readout instrument that displays both pH and conductivity values simultaneously. The model 3540 is designed to show both readings in real time and eliminates cross channel interference, as well as the need to either switch manually or automatically between measurements. The design also enables both dual channel and independent single channel operation.
1.2 Display and Controls The model 3540 has a back lit 1/8 VGA dot matrix LCD. In normal measurement mode the left-hand side displays the conductivity value and the right hand side the pH value. Both channels have their own temperature/ATC input displayed below the measured value, making them fully independent. The display includes a number of icons and prompts used to inform and indicate to the user the instrument status and measurement conditions.
The Enter key confirms selections as they are made in the set up menus. With the measurement screen displayed it acts as the Store [STO] key and stores the current readings in the internal memory. Up to 250 pH and conductivity readings can be stored. The action taken when the memory is full can be selected in the data logging set up menu. The four Cursor keys enable easy navigation through the set up menus, as well as selection of the required screen on the tabbed menu bar.
1.5 Good Practice Guidelines – pH 1. Selection of the correct electrode for your application is the most important factor in achieving good performance and extended electrode life. The use of Application Specific electrodes is recommended for all but the simplest sample matrix and measurement conditions. Please contact Jenway if you require further help or advice on electrode suitability and application support. 2. For best results follow Good Laboratory Practice (GLP) at all times.
13. Storage conditions can have a greater impact on electrode performance and operational life than sample type. Store only as directed in the instructions supplied with the electrode. For general guidance: Refillable Electrodes After Use Rinse thoroughly with deionised water. Leave the fill port open and immerse in a beaker of 4 pH buffer solution. Ensure both glass bulb and reference junction are covered. Overnight Rinse thoroughly with deionised water.
1.6 Good Practice Guidelines – Conductivity 1. After using the conductivity probe ensure it is rinsed thoroughly, or cleaned then rinsed if used in adhering samples. Between samples and for short-term storage the probe should be stored with the measuring plates immersed in a beaker of deionised water. This should be replaced regularly to ensure no contamination or growth occurs.
11. The temperature coefficient is very dependent on the solution being measured and its concentration level. The effect of temperature change on conductivity can be very significant, and if the temperature coefficient is not know it is wise to measure all samples at the reference temperature. 12. The TDS mode displays results that have been calculated from the conductivity measurement and assumes some knowledge of the electrolyte balance of the sample.
Section 2 Getting Started 2.1 Unpacking Remove the 3540 from the packaging and ensure the following items are included: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.
2.22 Electrode Holder Assembly The electrode holder requires minimal assembly (refer to the diagram below). 4 1 2 3 Decide on which side of the instrument you require the electrode stand to be positioned. Align the base plate with the shorter edge to the front of the instrument, so that the tapered sides match the taper on the instrument. Screw the rod into the base on the side required.
2.2.3 Power Supply, probes and accessory connection Rear Panel showing Input and Output Connectors 1. Ref Socket 2mm-pin type socket. Connection socket for separate reference electrode. When performing measurements with some pH and ion selective electrodes a separate reference electrode is needed. 2. pH Socket BNC type socket which allows combination pH or redox electrodes to be used. 3. Temp Socket 8-pin mini-DIN socket.
Section 2.24 Installation Verification 1. Connect the power supply, conductivity cell and ATC probe to the rear panel, as described in the previous section. (Do not immerse the probes in solution at this stage). 2. Connect the BNC shorting plug (009 146) to the pH input in place of the pH electrode. 3. Switch on the power at the mains supply socket, if necessary, then press the power on/off key on the instrument. 4.
Section 3 Set Up - General 3.00 General Set Up The general set up options include instrument wide functions that are relevant for both pH and conductivity channels. Functions that can be set in these menus are language, display brightness, GLP options, data logging options, clock, security and printer set up. Adjustments made to these settings are stored in non-volatile memory so will not need to be re-entered unless further changes are required.
3.10 Instrument Set Up The Instrument Set Up menu contains options for selecting the operating language and adjusting the brightness of the display to compensate for adverse lighting situations. Access the Instrument Set Up menu by carrying out paragraphs 3.01 to 3.05, then use the up or down arrow keys [ ] to move the highlight over the Instrument Set Up option then press the Enter key [ ]. The Instrument Set Up screen below will be displayed… Instrument Set Up screen 3.
To change the brightness of the display press the down arrow to highlight the LCD Brightness (%) option in the Instrument Set Up screen, then press the Enter key. The highlight will move across to the percentage previously set (or the default value of 050). A data entry box will appear in the centre of the screen. The box around the least significant digit will be flashing to indicate that this digit can be changed by pressing the up or down arrow keys.
3.20 GLP Set Up The GLP Set Up menu contains options for entering a User ID (4-digit code), a Batch ID (3-digit code) and the Security Code options. GLP functions relating to Calibration periods and calibration performance data are included in the Calibration Set Up menus for each channel individually. Access the GLP Set Up menu by carrying out paragraphs 3.01 to 3.05, then use the up or down arrow keys [ ] to move the highlight over the GLP Set Up option then press the Enter key [ ].
To change or set a Batch ID, press the down arrow to highlight the Batch ID option in the GLP Set Up screen, then press the Enter key. The highlight will move across to the Batch ID previously set (or the default value of 000). A data entry box will appear in the centre of the screen. The box around the least significant digit will be flashing to indicate that this digit can be changed by pressing the up or down arrow keys.
The following sub-menu is displayed. Security Set Up sub-menu 3.23 Data Entry Security To enable or disable data entry security (as described above) press the down arrow key in the Security Set Up sub-menu to highlight the Data Entry Security option in the menu. Then press the Enter key to move the highlight to the current selection. Press the up or down key to toggle between the Disabled and Enabled options.
3.30 Data Logging Set Up The data logging set up menu enables all the functions of the data logger to be set, including the event trigger, logging period and data destination. The function of the Clear [CLR] key on stored data can also be set, there is also a sub-menu for the Printer options. Access the Data Logging Set Up menu by carrying out paragraphs 3.01 to 3.05, then use the up or down arrow keys [ ] to move the highlight over the Data Logging Set Up option, then press the Enter key [ ].
To change the data logging trigger press the down arrow to highlight Data Log Event in the Data Logging Set Up screen, then press the Enter key. The highlight will move across to the default setting of ‘Manual’ or an alternative from the above if this has previously been changed. Use the up or down arrow keys to review the options and Use the up or down keys to select required Data Log Event press the Enter key to accept your preferred setting when this is highlighted on the display.
To change the data log interval from the default value or to set a new interval press the down arrow to highlight Data Log Interval in the Data Logging Set Up screen. Press the Enter key to move the highlight to the current selection. A data entry box will appear in the centre of the screen. The box consists of three pairs of digits separated by colons, from the left these represent hours, minutes and seconds.
3.35 Prompt Before Deleting Data stored in memory can be deleted by use of the clear [CLR] key on the keypad. If this option is enabled it allows the operator to be prompted by a message to confirm the deletion, or if disabled the result is deleted on the first press of the clear [CLR] key. The function of the clear [CLR] key can also be set in the Data Logging Set Up screen.
To change the clear key function, press the down arrow to highlight ‘Clr Key’ in the Data Logging Set Up screen, then press the Enter key. The highlight will move across to the default setting of ‘Disabled’ or an alternative from the above if this has previously been changed.
3.38 Print Channel This enables the print data to be configured so that just conductivity, just pH or conductivity and pH results are printed, reducing the print out of unnecessary data. To select which channel(s) are printed press the down arrow to highlight Print Channel on the Printer Set Up screen, then press the Enter key. The highlight will move across to the default setting of ‘Conductivity & pH’ or one of the above options if this has previously been changed.
3.43 Time Setting To adjust the time (see warning in paragraph 3.40) Press the down arrow to highlight the Time option in the Clock Set Up screen. Then press the Enter key to move the highlight to the current time setting. A data entry box will appear in the centre of the screen. The box consists of three pairs of digits separated by colons, from the left these represent hours, minutes and seconds.
Section 4 Conductivity Set Up 4.00 General Set Up The conductivity set up options include settings for all the functions that are relevant for the conductivity channel only. Functions that can be set in these menus are calibration settings, alarm settings, endpoint stability and ATC/temperature settings. Adjustments made to these are stored in non-volatile memory so will not need to be re-entered unless further changes are required.
4.10 Conductivity Calibration Set Up The conductivity calibration set up menu contains options for setting the Cell Constant (K factor), the EC ratio for TDS measurement, the Reference temperature and co-efficient as well as the ultra-pure water compensation algorithm. There are also sub-menus for entering Calibration standard values and for the calibration reminder. Access the Conductivity Calibration Set Up menu by carrying out paragraphs 4.01 to 4.
4.12 EC Ratio Setting The EC ratio is the factor that calculates the TDS value from the conductivity measurement. There are a number of different international and trade standards that specify this value. The model 3540 offers adjustment over the range of 0.5 to 0.8, this covers all potential requirements for this value. The most common standard requires a value of 0.60 that is the default setting.
Should you require to change the temperature co-efficient press the down arrow key to highlight Temperature Co-efficient (%) in the Conductivity Calibration set Up screen, then press the Enter key to move the highlight to the current selection. A data entry box will appear in the centre of the screen. Data entry box for setting the Temperature Co-efficient The box around the least significant digit will be flashing to indicate that this digit can be changed by pressing the up or down arrow keys.
4.16 Calibration Standard Set up A sub-menu for the selection of calibration standards, including the manual or automatic recognition of from one to three values is available. To select the sub-menu press the down arrow key to highlight Calibration Buffer Set up… in the Conductivity Calibration Set Up screen, press the Enter key to display the screen below… Calibration Standards for conductivity calibration Cal Buffers Used This option enables the number of standards used for calibration to be selected.
Press the down arrow in the Conductivity Calibration Set Up sub menu to highlight the Cal 1 (2 or 3) Buffer(mS) option. Press the Enter key to move the highlight to the current value. Use the Escape [ESC] key to move to other menu levels or continue with the Conductivity calibration settings as follows. A data entry box will appear in the centre of the screen. This has 7 digits and represents the calibration standard in value in mS, with three decimal places the least significant digit represents 1µS.
To select the sub-menu for setting the Calibration Reminder options press the up or down arrow key to highlight Calibration Reminder Set up… in the Conductivity Calibration Set Up screen, press the Enter key to display the screen below… Calibration Reminder Set Up screen Cal Reminder The calibration reminder function can be enabled or disabled.
Cal Reminder Audible Alarm When the cal reminder interval has elapsed a visual warning is displayed in place of the relevant reading, to enhance this warning an audible alarm that bleeps every 5 seconds can also be enabled. This audible warning is active whenever the conductivity tab on the menu bar is selected. To enable the audible alarm, press the down arrow to highlight the Cal Reminder Audible Alarm option on the Cal Reminder sub-menu, then press the Enter key.
To enable the alarms and set the relevant high and low alarm levels press the down arrow key in the Conductivity Set Up menu to highlight Alarms Set Up… Conductivity Set Up menu – Alarms Set Up highlighted Press the Enter key to display the Alarms Set Up menu as below… Alarms Set Up Menu 4.21 Alarm Outputs This option enables or disables all of the alarm functions and overrides the audible alarm warning that can be separately disabled/enabled only when this function is enabled.
4.23 Alarm Point Settings… A sub-menu for setting the high and low alarm points for each mode can be accessed by pressing the down arrow in the Alarms Set Up menu to highlight Alarm Point Settings… then press the Enter key for the following display… High and Low alarm settings High and Low alarm levels are available for Conductivity, TDS and Resistivity, these are effective when the relevant mode is selected (use the up or down arrow when the Cond tab is highlighted in the main measurement screen).
icon will then be displayed and an optional audible alarm can be enabled. The period over which the instrument looks for stability can be adjusted for special applications where slow changes, reaction rates and special probe types are used. Measurement display showing two endpoint icons To adjust the Endpoint Detection settings select Endpoint Detection Set Up… in the Conductivity Set Up menu and press the Enter key to display the menu as follows… Endpoint Detection Set Up menu 4.
4.33 Endpoint Stability (Sec) The endpoint algorithm looks for a reading that is stable, within a certain window of variation, over a set period of time. The default is 5 seconds and this is ideal for all normal measurement applications, giving the fastest result with maximum confidence in stability. Should a specific application require this time period to be increased or decreased it can be adjusted as follows.
Escape key to return to other menu levels or continue with setting the Manual Temperature Compensation value as follows. 4.42 Manual Temperature (oC) Should manual temperature compensation be required a suitable value can be entered by pressing the up or down arrow key in the Temperature Set Up menu to highlight the Manual Temperature (oC) option. Then pressing the Enter key will display a data entry box.
Section 5 pH Set up 5.00 The pH set up options include settings for resolution, calibration values and number of buffers as well as alarm settings, endpoint stability and ATC/temperature settings. Adjustments made to these are stored in non-volatile memory so will not need to be re-entered unless further changes are required. They will also be retained regardless of the power connection to the instrument. 5.01 Connect the power supply as described in section 2.2.3.
5.10 pH Resolution The pH display can be set to have a resolution of 0.1pH, 0.01pH or 0.001pH depending on your application and regulatory/reporting requirements. To change the displayed resolution press the down arrow key in the pH Set Up menu to highlight pH Resolution, then press the Enter key. The current setting will be highlighted, use the up and down arrow keys to cycle through the three options detailed above.
5.30 Calibration Set Up A separate sub-menu is available for entering and setting calibration data. To access this sub-menu press the down arrow key in the pH Set Up menu to highlight Calibration Set Up… then press the Enter key. The following sub-menu will be displayed… pH Calibration Set Up Sub-Menu Cal Buffers Used Up to three different buffers can be used to perform a calibration.
Selecting the Manual option enables alternative buffers to be used by entering their respective values as the Manual Cal 1 to 3 Buffers in this sub-menu. The buffer values entered must be the temperature-corrected values at the temperature the calibration is carried out – for maximum accuracy buffers and samples should be maintained at this temperature when using this calibration method.
right or left arrow keys can be used to move the highlight to the other digits which in turn can be set, with the up or down arrow keys, to the desired level. When all digits are set and the desired value displayed in the data entry box then press the Enter key to confirm the setting. Press the Escape [ESC] key to return to other menu levels or continue with the pH Calibration set up as follows.
calibration reminder interval can be set from 1 hour to 999 hours and can only be cleared by carrying out a new calibration. To set the calibration reminder interval press the down arrow key in the Calibration Reminder sub-menu to highlight the Cal Reminder Interval (Hr); then press the Enter key. A data entry box will appear in the Cal Reminder Interval data entry box centre of the screen.
An output from the rear panel sockets is also available to switch external audio/visual alarms or for simple control/telemetry functions via external relays. Details of the relevant connections for these outputs are contained in Section 10.6.
when it is highlighted on the display. Then use the ESC key to return to other menu levels, the main measurement screen or continue with the alarms settings as follows. 5.42 Audible Alarm Warning With the Alarm Outputs enabled the internal audible alarm can be separately enabled or disabled so as not to be intrusive when not required or to complement the visual alarm bell icon when necessary.
the Enter key to accept this value. Use the up or down arrow key to adjust other alarm settings as required or press the ESC key to escape to other menu levels or return to the main measurement screen. 5.44 pH Endpoint Set Up All measurements made with electrochemical sensors are subject to a response time for the sensor to equilibrate to the sample conditions and while the temperature sensor compensates for temperature differences between samples and ambient conditions.
5.46 Endpoint Audible Alarm To complement and re-enforce the display of the endpoint icon an audible alarm can be enabled to indicate a reading reaching stability. To change the Endpoint Audible Alarm setting press the down arrow key to highlight Endpoint Audible Alarm in the Endpoint Detection Set up menu then press the Enter key. The highlight will move to the current setting.
5.48 pH ATC/MTC Set Up Temperature measurement and compensation processes are carried out automatically during measurement procedures. However adjustments can be made to display temperature values in the Celsius or Fahrenheit scales and where automatic compensation is not required, or possible, then a manual compensation value may be entered.
Section 6 6.10 Calibration pH Calibration Up to three calibration points may be used during a pH calibration procedure. Autobuffers may be selected from any one of four sets of five values. These will be automatically recognised and so can be measured in any order. Their temperature corrected values will also be automatically displayed. Up to three values can be entered manually, but these must all be entered as values at a fixed temperature and calibration must be carried out at this same temperature.
The prompts in the preceding display request the first point of a three point calibration (1 / 3) indicating that the current buffer is 7.015 at 21.6oC. The following display shows how this varies if a 4pH buffer is used as the first calibration point. pH calibration screen showing 4pH as the first of three calibration points When the endpoint icon is displayed a further press of the CAL key will confirm the calibration and set the display to the temperature-corrected value for that buffer.
The display now changes to request the third buffer (3 / 3), rinse the electrode with de-ionised water and blot up any excess with clean, soft tissue, before immersing the electrode in the next buffer. While the electrode is not transferred a warning triangle will be displayed in the icon bar. Buffer 3 of 3 with an expected value of 10.039 When the endpoint icon is displayed a further press of the CAL key will confirm the calibration and set the display to the temperature-corrected value for that buffer.
6.20 Conductivity Calibration There are three methods for calibrating the conductivity channel. The simplest is by setting the cell constant (K factor) in the set up menu, or alternatively a one, two or three point calibration can be carried out against any of the four automatically recognised standard solutions. If calibration to alternative standards is required these can be entered for manual calibration. 6.
careful re-calibration against precision standards a new cell constant can be determined after a period of use. To calibrate against a known cell constant (K Factor), select the Setup tab using the right or left arrow keys, then select Conductivity Set up using the up or down arrow keys. Press Enter and select Calibration Set up using the up or down arrow keys. Press Enter and use the down arrow key to highlight the Cell Constant (K) option then press Enter.
Details and prompts are shown in the Icon bar throughout the calibration procedure. The following display shows the first point in a three point calibration (1/3), if a two or one point calibration had been selected then 1/2 or 1/1 will be displayed. The first standard has been recognised as 84µS. Prompt shows first calibrant is recognised as 84.
If a two-point calibration has been selected then the main measurement screen is returned at this point. The display now changes to request the third standard (3 / 3), rinse the probe with de-ionised water and blot up any excess with clean, soft tissue, before immersing it in the next solution Prompt shows third standard recognised as 12.
Section 7 7.1 Measurements pH and Conductivity Measurement Following successful calibration of one or both channels, measurement is simply carried out by immersing the relevant electrodes in the sample and taking the reading when a stable endpoint is reached. Remember to rinse all the probes with deionised water between samples and blot off any excess with clean, soft tissue before immersing in the next sample.
7.20 mV Measurement The mV measurement mode can be used for Redox (ORP) measurement as well as probe diagnostics. The mV mode can be accessed by pressing the up or down arrow key when the pH tab is highlighted in the main measurement screen. In many instances calculation and comparison are made easier by calibrating out any probe off-set, this can be done using the Relative mV (Rel mV) function. This function can pull in to zero + or – 1999.9 mV which is half the full-scale range.
An example screen of stored results To review stored results use the right or left arrow key to highlight the Results tab. See section 3.3 for details of the alternative actions that can be taken when the memory is full and for the various functions of the clear [CLR] key. Results can be transmitted to a PC by pressing the print key. 7.4 Resistivity Measurement Resistivity is the reciprocal of conductivity and is sometimes used as the unit for measurement of pure waters.
An example screen of stored results To review stored results use the right or left arrow key to highlight the Results tab. See section 3.3 for details of the alternative actions that can be taken when the memory is full and for the various functions of the clear [CLR] key. Results can be transmitted to a PC by pressing the print key. 7.
Maintenance & Troubleshooting 8.1 General The Model 3540 is designed to give optimum performance with minimum maintenance. It is only necessary to keep the external surfaces clean and free from dust. To give added protection when not in use the unit should be disconnected from the mains supply and covered with the optional dust cover (060 406). For longer-term storage or re-shipment it is recommended that the unit be returned to the original packing case.
8.3 Troubleshooting - pH Fault Possible Cause Action No display Check power supply Check that correct 9V ac power supply is connected and switched on Erratic display Check power supply The 3540 must be used with the supplied 9V ac power supply The 3540 will not operate with other power supply units Drifting, erratic readings Electrode fault Use BNC shorting plug to test the 3540 (refer Section 8.
8.
8.60 Functional Check – Conductivity A simple but effective method for checking the conductivity channel can be made with two 10K ohm resistors. One for checking the ATC function and the two together for checking the conductivity function. Disconnect all probes and connectors from the 3540 except for the power supply jack plug. The Temperature display below the conductivity reading should indicate 25.
conductivity reading should be between 180 and 220µS depending on the last calibration or cell constant setting – if in doubt set the cell constant to 1.000 and recheck. If this functions correctly then any problem is most likely to be associated with the probe – if it fails to work correctly contact your local distributor or Jenway for service advice. 8.
Section 9 Optional Accessories 9.1 Accessories The following items are available as optional accessories: 060 406 037 701 037 801 Dust cover IrDA/Serial printer supplied with a roll of thermal paper, serial connection lead, power supply (UK), power connection lead and pouch Interface cable kit pH Electrodes 924 001 924 005 General purpose, epoxy bodied combination, 12mm diameter. General purpose, glass bodied combination, 12mm diameter.
Miscellaneous 025 160 025 161 3M KCl electrode fill solution (100ml) Electrode cleaning solution (500ml) Conductivity Calibration Standards 025 138 025 156 025 164 025 139 025 165 1413µS calibration standard (500ml) 12.
Section 10 Specification & Data 10.
10.2 Analogue Output The Model 3540 is provided with 2 x 4mm sockets, marked as Analog O/P on the rear panel. The level is proportional to the displayed reading, depending on the measurement mode: pH measurement and calibration modes mV measurement mode Conductivity 10.3 1mV per 0.01pH 1mV per 1mV 1mV per least significant digit RS232 Serial Interface The bi-directional RS232 interface is available on the rear panel 9 way D type connector.
Setting of these options is detailed in Section 3.37 and 3.38 The Model 3540 supports both hardware (CTS/RTS) flow control and software XON/XOFF flow control. Pressing the PRINT key outputs from the RS232 interface. Sending an ASCII “D” to the 3540 causes a printout of the current displayed reading, plus sample number. Sending an ASCII “C” causes a printout of the last calibration parameters. Sending an ASCII “P” causes a printout of the stored readings. 10.
Most recent calibration information Eo value Slope efficiency Buffer type This will also be followed by result data dependent on the mode selected. Time and date of the stored readings will be displayed. An asterisk (*) indicates that manual temperature compensation is being used. The letter R will indicate a reading in the Relative mV mode. A batch number will identify each reading. A calibration will reset the print out and the header information will be re-printed.
Addendum pH Auto-Buffer & Conductivity Auto-Standard Sets Ad.1 Temperature pH 2 at 25oC pH 4 at 25oC pH 7 at 25oC pH 9.2 at 25oC pH 10 at 25oC 0oC 2.010 4.000 7.120 9.520 10.270 Jenway Auto-Buffer Set 10oC 20oC 25oC 30oC 2.010 2.010 2.000 19.90 4.000 4.000 4.005 4.009 7.065 7.020 7.005 6.990 9.381 9.261 9.207 9.152 10.180 10.005 10.000 9.950 0oC 1.670 4.000 6.975 9.460 13.410 10oC 1.670 4.000 6.925 9.340 13.010 0oC 3.140 4.680 6.895 9.485 13.770 40oC 2.010 4.027 6.975 9.060 9.866 50oC 2.000 4.050 6.
EC Declaration of Conformity JENWAY Model 3540 pH/Conductivity Meter complies with the following European Standards: EN 50081-1:1992 electromagnetic compatibility – Generic emission standard EN 50082-1:1992 electromagnetic compatibility – Generic immunity standard (Performance criterion B) EN 61010-1:2001 Safety requirements for electrical equipment for measurement, control and laboratory use Following the provision of: EMC Directive – 89/336/EEC and Low Voltage Directive – 73/23/EEC Carl Warren Technical
