Mettler Toledo DL15 Instruction Manual

Operating Instructions

Titrator

DL15

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Table of contents

METTLER TOLEDO DL15 I

Table of Contents

1. Introduction 5

2. Safety measures 6

3. Standard equipment and Installation 7

3.1 Standard equipment DL15 Titrator 7

3.2 Installation 9

3.2.1 Attaching the titration stand to the titrator 9

3.2.2 Installing the burette 10

3.2.3 Installing the magnetic stirrer 10

3.2.4 Swiveling the titration stand 11

3.2.5 Attaching and removing the titration beaker 12

4. The titrator 13

4.1 Design of the titrator 13

4.2 Connections at the rear of the titrator 13

4.3 The operating concept 14

4.3.1 The display 15

4.3.2 The arrow keys 15

4.3.3 The function keys 15

4.3.4 The input keys 15

4.3.5 The menu keys 16

4.3.6 The Help function keys 17

4.3.7 The Escape key 17

4.3.8 The Reset key 17

4.3.9 The Home screen 18

5. Setup 19

5.1 Opening the Setup menu 19

5.2 Titrants 19

5.2.1 Adding a titrant 20

5.2.2 Modifying a titrant 20

5.2.3 Deleting a titrant 22

5.2.4 Printing a titrant 23

5.2.5 Titer determination from the titrant setup 23

5.3 Sensors 25

5.3.1 Adding a sensor 25

5.3.2 Modifying a sensor 26

5.3.3 Deleting a sensor 28

5.3.4 Printing a sensor 28

5.3.5 Sensor calibration from the sensor setup menu 29

5.3.6 Sensor test from the sensor setup menu 32

5.4 Peripherals 35

5.4.1 Setting up a printer 35

5.4.2 Setting up a balance 36

5.5 Standards 37

5.5.1 Adding a standard 37

5.5.2 Modifying a standard 37

5.5.3 Deleting a standard 39

5.5.4 Printing a standard 39

Table of contents

II METTLER TOLEDO DL15

5.6 Blank values 40

5.6.1 Adding a blank value 40

5.6.2 Modifying a blank value 40

5.6.3 Deleting a blank value 42

5.6.4 Printing blank values 42

5.6.5 Blank value determination from the blank values setup menu 43

5.7 Main methods 43

5.7.1 Assignment of a function key 44

5.7.2 Changing the assignment of a function key 44

5.7.3 Deleting the assignment of a function key 45

5.8 User management 45

5.8.1 Adding a user 45

5.8.2 Deleting a user 46

5.8.3 Defining an active user 46

5.8.4 Defining access rights 47

5.9 Settings 47

5.9.1 Setting the language 48

5.9.2 Setting the date 48

5.9.3 Setting the time 49

5.9.4 Defining the temperature unit 49

5.9.5 Entering the titrator ID 49

5.9.6 Entering a report header 50

5.9.7 Setting the beeper sound 50

5.10 Titration stand 50

6. Methods (Method) 53

6.1 Starting a method 54

6.1.1 Starting methods from the method editor 54

6.2 Creating a method 55

6.3 Modifying a method 56

6.3.1 Sample 58

6.3.2 Stir 60

6.3.3 Measure 60

6.3.4 EP titration 61

6.3.4.1 Control param. 62

6.3.4.2 Recognition 65

6.3.4.3 Termination param. 65

6.3.4.4 Evaluation 66

6.3.5 Calculation 67

6.3.5.1 Table of formulas for the calculation of results 70

6.3.6 Report 71

6.4 Deleting methods 72

6.5 Printing a methods list 73

6.6 Printing a method 73

6.7 Predefined methods 74

7. Series 75

7.1 Starting a sample determination using the Series key 75

7.2 Starting a titer determination using the Series key 76

7.3 Starting a blank value determination using the Series key 77

8. Analysis (Run) 79

8.1 Starting a sample determination using the Run key 79

8.2 Starting a titer determination using the Run key 80

8.3 Starting a blank value determination using the Run key 80

Table of contents

METTLER TOLEDO DL15 III

9. Performing a titration 83

9.1 Preparations 83

9.1.1 Filling the burette (rinsing) 84

9.2 Performing titration method 920 84

10. Auxiliary functions (Info, Sensor, Stirrer, Burette, Report, Results) 89

10.1 Information menu 89

10.2 Sensor 89

10.2.1 Measuring temperature 90

10.2.2 Measuring potential 90

10.2.3 Calibrating a sensor 91

10.2.4 Testing a sensor 91

10.3 Stirrer 91

10.4 Burette 92

10.4.1 Rinsing the burette 92

10.4.2 Rinsing the tip 93

10.4.3 Dispensing 93

10.4.4 Manual titration 93

10.5 Report 95

10.6 Results 95

10.6.1 Displaying and printing results 96

10.6.2 Statistics 96

10.6.3 Terminating the series 98

11. Error messages, malfunctions and hardware tests 99

11.1 Global errors and malfunctions 99

11.2 Hardware tests 100

11.2.1 User interface 100

11.2.2 Communication interfaces 101

11.2.3 Auxiliary I/O 102

11.2.4 pH input value 103

12. Optional accessories and maintenance 105

12.1 Optional accessories 105

12.2 Service and maintenance 107

12.2.1 Cleaning 107

12.2.2 Disposal 107

13. Technical data 109

Appendix: Predefined calibration standards 120 Index 124

Table of contents

IV METTLER TOLEDO DL15

Introduction

METTLER TOLEDO DL15 5

1. Introduction

The DL15 Titrator is the ideal solution for all requirements in the food industry, water/ wastewater analysis, and the chemical industry when all that is needed is an endpoint titration or a pH measurement. The DL15 is mainly used to determine the acid and base content of a sample. It features easy-to-understand intuitive user guidance so that, for example, pressing the Run button twice starts the method you last ran. The user can assign three other methods to individual function keys, making methods easy to find and start. The keys used for the most frequently used manual functions are identified by pictograms. Titrants and sensors can be selected from the instrument’s database. Alphanumeric input is easily entered by means of a special keypad, just like with a mobile phone. There is no need to connect an external keyboard. The DL15 calculates the analytical results in predefined units and sends an analysis report to commercially available printers.

Safety measures

6 METTLER TOLEDO DL15

2. Safety measures

The titrators have been tested for the experiments and purposes documented in this Operating Instructions. This does not, however, absolve you from the responsibility of performing your own tests on the products supplied by us regarding their suitability for the methods and purposes you intend to use them for. Please adhere strictly to the following safety measures.

Measures for your protection

Risk of an electrical shock

Risk of explosion

Corrosive chemicals

Caution

– Make sure that the power cable supplied is plugged into a power outlet that is

ground! A technical defect could otherwise have lethal consequences.

– Switch off the instrument and pull out the power cable before you open the instru-

ment housing! An electrical shock could have lethal consequences.

Do not work in an environment subject to the risk of explosions! The instrument

housing is not gastight (risk of explosion through spark formation, corrosion through the ingress of gases).

– Make sure that the titration beaker is always securely attached in the titration head!

If the beaker falls out, you could injure yourself when working with poisonous titrants and solvents, strong bases or acids.

– When using chemicals and solvents, follow the manufacturers' instructions and the

general rules for safety in the laboratory!

Measures for operational safety

– Have the instrument serviced only by METTLER TOLEDO Service! – Wipe off any droplets of liquid! The instrument is not watertight. – Eliminate the following environmental effects:

• strong vibrations,

• direct sunlight,

• humidity over 80%,

• temperatures below 5 °C and over 40 °C,

• strong electric or magnetic fields!

Standard equipment and Installation

METTLER TOLEDO DL15 7

3. Standard equipment and Installation

3.1 Standard equipment DL15 Titrator

The parts are given with order number and the number of items supplied. For additional orders, some parts are only available as a minimum order quantity. In this case, the minimum order quantity is noted after the order number. The standard equipment and the optional accessories for the DV1020 burette are listed in the operating instructions for the interchangeable burette. This is supplied with the burette.

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Titrator

External power supply

51107777

Power cable (country specific)

(example)

Holder for titration stand

51109361

Fixing screw (for holder)

51109084

Magnetic stirrer

51108750

Magnetic stirrer bars

51191159

Cap (2x)

51107608

Dummy cover

51107600

Titration stand, manual

51109058

Spacing ring

00023842

Clamping ring

00025653

Threaded ring

00025652

DG115-SC Combined glass electrode with sleeve frit for titrations in aqueous media

00089806

Standard equipment and Installation

8 METTLER TOLEDO DL15

Stopper ST 7.5 (4x)

00023452

(minimum order quantity 5 pcs.)

Connection cable for HP compatible printer

51107780

2 g glass wool 51108143

Interchangeable burette, complete (for further accessories: see operating instructions for the interchangeable burette)

DV1020

DL15 Applications Brochure English

Operating Instructions English

Triaxial cable SC-LEMO-60 (length: 60 cm)

00089601

Electrode sleeve 00025654 (minimum order quantity 5 pcs.)

Titration vessel 100 mL polypropylene (2x)

00101974

(set of 1400 pcs.)

Drying tube holder

00023915

Drying tube

00023961

Protective cover for keypad

51107666

(minimum order quantity 3 pcs.)

Stopper ST 14.5 (5x)

00023451

(minimum order quantity 5 pcs.)

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Standard equipment and Installation

METTLER TOLEDO DL15 9

3.2 Installation

3.2.1 Attaching the titration stand to the titrator

When the titration stand is delivered, the spacing ring, clamping ring and threaded ring are already mounted. The holder for the titration stand still has to be fixed to the titrator with the corresponding screw. Afterward, the assembled titration stand can be inserted from above. The diagram below shows how the titration stand is attached to the titrator and how the titration stand can be assembled and disassembled.

Cap

Screw

Titration stand

Spacing ring

Clamping ring

Threaded ring

Titration beaker

Holder for titration stand

Standard equipment and Installation

10 METTLER TOLEDO DL15

3.2.2 Installing the burette

1. Screw the burette with holder onto the titrant bottle (see operating instructions for burette.

2. Slide the burette onto the titrator: The slot on the cam and piston rod must be parallel plug-in unit. (If this is not the case, press the Reset key.)

3. Turn the arrestment knob in the direction shown by the arrow to fasten the burette.

4. Place the dispensing tube into one of the openings in the titration stand.

• When you rinse the burette and tubing, place the dispenser tube in a waste container!

Fixing screw for titration stand holder

Cam

Piston rod of the burette drive

Arrestment knob

3.2.3 Installing the magnetic stirrer

The titrator has a slot on the right side of the housing into which the METTLER TOLEDO magnetic stirrer can be inserted as shown in the following diagram. The magnetic stirrer is inserted into the slot of the titrator from the right so that it slides into the guide rail. The connection cable of the magnetic stirrer is guided out to the rear in the slot on the right side of the housing between the housing and the holder for the titration stand. To do this you may have to briefly remove the holder for the titration stand. The connection cable of the magnetic stirrer is connected to the "Magnetic stirrer" connection at the rear side of the housing. The arrow on the mini-DIN plug must point toward the head of the screw.

Magnetic stirrer

Standard equipment and Installation

METTLER TOLEDO DL15 11

3.2.4 Swiveling the titration stand

The titration stand can be swiveled in order to work with the magnetic stirrer. If the compact stirrer is used, it is advisable to use the titration stand in the swiveled position.

You can swivel the titration stand in and out. To do this, you lift the titration stand slightly and pull it upward a little bit out of the holder. Now you can swivel it to the desired position and then let it slide back into the holder.

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Standard equipment and Installation

12 METTLER TOLEDO DL15

3.2.5 Attaching and removing the titration beaker

To insert a titration beaker in the titration stand, you must first make sure that the threaded ring is loose (a quarter to half a turn is sufficient). Then, carefully insert the titration beaker from below into the titration stand A, and tighten the threaded ring B.

To remove the titration beaker from the titration stand, loosen the threaded ring about a quarter to half a turn C, and then carefully remove the titration beaker downward out of the titration stand.

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The titrator

METTLER TOLEDO DL15 13

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4. The titrator

4.1 Design of the titrator

4.2 Connections at the rear of the titrator

Magnetic stirrer

Titrator stand

Burette

Titrant bottle

Arrestment knob

Sample beaker

Keypad

RS-P42 printer

Balance

HP compat.

printer

Power supply

Magnetic stirrer

Overhead stirrer

mV / pH electrode

Reference electrode

Temperature sensor

Polariz. electrode

Rondolino

not assigned

The titrator

14 METTLER TOLEDO DL15

The following devices can be connected to the corresponding interfaces:

Connection Device

mV/pH mV / pH electrode (sensor)

Ref Reference electrode

PT1000 PT1000 temperature sensor

Pol polarized electrode (sensor)

Overhead Stirrer Overhead stirrer

Magnetic Stirrer Magnetic stirrer

Balance Balance (RS232C)

Rondolino TTL I/O Rondolino, external devices

RS-P42 RS-P42 (GA-42) printer (RS232C)

Computer not assigned

Printer HP-compatible printer (Centronics)

5V/24V DC Power supply

4.3 The operating concept

The operating console of the titrator consists of the display in the middle with several groups of keys arranged around it. The various functional areas are described in the following sections.

The titrator

METTLER TOLEDO DL15 15

4.3.1 The display

The display consists of four different elements. The title line across the top shows the name of the menu (B) and submenu (A) that you are currently using, or the name of the screen. On the right-hand side of the screen there is a scroll bar (D). This has a small black bar that represents the portion of the menu shown on the display. You can move the visible part of the menu upward or downward through the display area using the arrow keys. The black-inverted line (C) always displays the current selection.

The three black-inverted boxes (E) across the bottom line of the display show the functions to which the function keys directly below (F1, F2 and F3) are assigned for the menu item selected.

4.3.2 The arrow keys

The arrow keys are located on the right of the display. You can use these to move the black scroll bar up or down within a menu to select a menu item. If you simultaneously press an arrow key and the Shift key (arrow pointing upward), the scroll bar is shifted upward (or downward) three lines.

4.3.3 The function keys

The function keys are located directly below the display. Their assignment depends on the particular menu item selected and is shown by the three black-inverted boxes across the bottom line of the display, for example, Print for the command to print, or OK to confirm a selection or a change.

4.3.4 The input keys

The input keys are located on the right-hand side of the operating console. They allow alphabetical, numerical and special characters to be entered.

Entering character strings into text boxes

To enter a number or one of the letters written above a number, press the corresponding number key repeatedly until the desired character appears in the display. After a short pause, the cursor jumps one step further for you to enter the next character.

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The titrator

16 METTLER TOLEDO DL15

- Pressing the number key 2 once, for example, writes the letter "a"; pressing it three time, the letter "c", and so on.

- To obtain large characters, you must press and hold down the Shift key (arrow pointing upward) while selecting the character.

- You can delete the last character by pressing the Del key. If you simultaneously press the Delete key and the Shift key, the entire content of the text box is deleted.

- To insert a space, press the number key 0.

- You can insert special characters by simultaneously pressing the number key 1 and the Shift key. A screen appears displaying all the available special characters. The black box indicates the character currently selected.

- Select the desired character using the arrow keys and the < and > keys.

- Press OK to enter the special character in the text area.

Entering numbers into number boxes

Only numbers, a point, and a minus sign can be entered into number boxes.

- To enter a number, press the desired number key.

- To enter a negative sign, simultaneously press the . and the Shift keys.

4.3.5 The menu keys

Using the menu keys, you can call up the four main menus of the titrator. Each of these three menus has a particular assignment for performing an automatic analysis.

The Setup key opens the Setup menu of the titrator. All the resources such as titrants, sensors, standards and blank values necessary for the titration are stored and managed in this menu. In addition, you can select the internal titrator settings you require and configure peripheral devices.

The Method key opens the Method menu of the titrator. The methods stored in the titrator are managed in this menu. You can store your own methods, delete and modify them. A number of methods developed by METTLER TOLEDO are already stored and can be directly used to perform analyses or be used as templates for new methods. The resources you want to use for a method must be defined and stored beforehand in the Setup menu.

The Run key opens the Start menu to perform an analysis. Methods used for different determinations can be selected and started.

The Series key opens the start menu to perform a sample series analysis. Methods used for different determinations can be selected and started An automation of the series determination can be achived by using a Rondolino sample changer.

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The titrator

METTLER TOLEDO DL15 17

4.3.6 The Help function keys

The Help function keys let you access functions that are not directly involved in performing a sample analysis, but nevertheless in some way support it (hence the name Help functions). Examples of such functions are the rinsing of burettes, the calibration or testing of a sensor or the display and management of analytical results.

This menu lets you measure the pH, potential or temperature of a solution and test and calibrate pH and ISE sensors.

The burette and the burette tip can be rinsed, and any volume you like dispensed. You can perform a manual titration.

The variable speed stirrer can be switched on and off.

You can view the titrator information and open a menu to test the titrator hardware and the connected devices.

You can view, print and manage the results of your analyses including statistical evaluations.

In the Report menu you can define and print additional reports.

4.3.7 The Escape key

By pressing the Escape key, you can quit a menu or a selection at any time and discard the changes you made. You always return to the previous menu and the original values and names remain the same.

4.3.8 The Reset key

Pressing the Reset key terminates analyses, rinsing or dispensing processes, and other actions. The titrator is then reset and you return to the Home screen. Data that was not saved beforehand is lost.

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The titrator

18 METTLER TOLEDO DL15

4.3.9 The Home screen

The Home screen appears on the display as soon as you switch on the titrator. It is the starting point for operating the titrator. Each time you reset the titrator by pressing Reset, you return to the Home screen. The screen displays the following important information:

• the current date and time.

• the current user. (See "5.8.3 Defining an active user")

• the access rights for the active user: Expert or Routine.

(See "5.8.4 Defining access rights for active users")

• the assignment of the F1, F2 and F3 function keys with the main methods.

(See "5.7 Main methods")

Setup

METTLER TOLEDO DL15 19

5. Setup

In this chapter you learn how to set up the titrator for your specific requirements.

To perform a titration, you must first define and configure the resources (titrants, sensor, peripherals, etc.) used for the method in the titrator.

5.1 Opening the Setup menu

- Press the Setup button to open the Setup menu.

- A list of the resources appears.

You can scroll the list upward or downward using the arrow keys on the right next to the display. The black-inverted line always shows the current selection.

If you press Print, the list with the available entries for the selected resource is printed. See "5.4.1 Setting up a printer" If you press OK, the list of the selected resources appears on the display.

5.2 Titrants

- Press Setup to open the Setup menu.

- Select "Titrant" using the arrow keys and press OK to confirm. The list of the titrants

stored in the titrator appears.

The titrants used by the METTLER methods are already preset in the titrator. You can delete titrants, and modify or print the parameters of the selected titrants. Furthermore, you can determine and store the titer for each titrant using an automatic function.

• You can add a new titrant by modifying the parameters of an existing titrant and then

storing it under a new name.

• A maximum of 30 titrants can be stored in the titrator.

 

Setup

20 METTLER TOLEDO DL15

5.2.1 Adding a titrant

Proceed as follows to define a new titrant:

- Press Setup to open the Setup menu.

- Select "Titrant" using the arrow keys and press OK to confirm. The list of the titrants stored in the titrator appears.

- Select an existing titrant from the list of titrants and press Modify.

- Change the name to the name of the new titrant you want to define.

- Change the parameters of the titrant corresponding to the new titrant you want to define. See "5.2.2 Modifying a titrant".

- Press Save to confirm the changes you have made.

- The new titrant appears in the list.

• You can discard the changes you have made by pressing Esc to quit the selection. In this case, the titrant is not stored.

• Determine the titer of the new titrant using the automatic titer determination (Titer key) if you have not already entered it manually. See "5.2.5 Titer determination from the Titrant setup".

• In any case, first change the name of the titrant. Otherwise the changes you made for the existing titrant will be effective on pressing the Save key, and no new titrant will be stored in the titrator!

5.2.2 Modifying a titrant

- Press Setup to open the Setup menu.

- Select "Titrant" using the arrow keys and press OK to confirm. The list of the titrants stored in the titrator appears.

- Select the titrant whose parameters you want to change.

- Press Modify.

- The list of parameters of the selected titrant appears and the individual parameters can be selected and changed.

- Press Save to accept your changes and quit the menu, or press Esc to discard your changes and quit the menu.

All titrants contain the following parameters:

Setup

METTLER TOLEDO DL15 21

Name The name of the titrant.

Conc. [mol/L] The concentration of the titrant in [mol/L].

Titer The titer can be automatically determined using a titer determi-

nation, or manually entered. If the titer is determined through a titer determination, the current date and time are stored.

Minimum The "Minimum" parameter lets you define the lower limit for the

range within which the titer must be.

Maximum The "Maximum" parameter lets you define the upper limit for the

range within which the titer must be.

Titer This parameter indicates whether the titer determination was

automatically determined ("Determined") or manually entered ("Edited").

Standard Here you can select one of the standards defined in the titrator

to determine the titer of your titrant.

Burette Using this parameter you can define the burette volume. Pos-

sible values are 1, 5, 10 and 20 mL.

Charge With this parameter you can record information about the batch

from which the titrant originates.

Fill rate [%] The "Fill rate" indicates how quickly the burette is filled with

titrant. Filling the burette at the highest rate corresponds to a fill rate of 100%, and at the lowest rate to a fill rate of 30%. The preset value is 100%

Check after [day] This value is used to calculate the expiration date for the titrant.

A period of 0 to 100 days can be defined. If the parameter has the value 0, no expiration date is determined.

Expiry If the value 0 is entered for the "Check after" parameter, no

expiration date is calculated.

Date The date of the last titer determination. Each time you store the

titrant, the date is set to 00-00-0000.

Time The time of the last titer determination. Each time you store the

titrant, the time is set to 00:00.

Setup

22 METTLER TOLEDO DL15

• If you change the name of a titrant and save your changes, a new titrant is created under the new name.

• If the value for the titer determined by a titer determination or the manually entered value is outside the range defined by "Minimum" and "Maximum", an error message appears and the titer must either be determined or entered again.

• When you use a titrant of higher viscosity, it is advisable to reduce the fill rate in order to prevent air being sucked-in when filling the burette.

• If, at the start of an analysis, the titant has expired (the expiration date has been exceeded), a message appears to draw your attention to this. If you still want to perform the determination, you must confirm the message. In the report, a corresponding line appears that notes that the titrant has expired.

5.2.3 Deleting a titrant

- Press Setup to open the Setup menu.

- Select "Titrant" using the arrow keys and press OK to confirm. The list of the titrants stored in the titrator appears.

- Select the titrant you want to delete.

- Press Delete.

- In the dialog that follows, you are asked whether you really want to delete the selected titrant. Confirm deletion by selecting "Yes" and pressing OK, or terminate deletion by selecting "No" and pressing OK to confirm.

• You can only delete titrants that have not been used in a method.

• Titrants referenced by METTLER methods cannot be deleted.

Setup

METTLER TOLEDO DL15 23

5.2.4 Printing a titrant

- Press Setup to open the Setup menu.

- Select "Titrant" using the arrow keys and press OK to confirm. The list of the titrants

stored in the titrator appears.

- Select the titrant whose parameters you want to print.

- Press Print.

- The parameters of the selected titrant are printed on the printer as soon as you con-

firm by pressing OK.

5.2.5 Titer determination from the titrant setup

The accuracy of the results of your analysis depends on the accuracy with which you determine the concentration of your titrant. When you prepare a titrant, a number of errors can occur that cause the actual concentration (C

actual

) to deviate from the desired concentration (C

nom

) of your titrant. The quotient of the actual concentration of the titrant and its desired concentration is called the titer of the titrant:

In the ideal case, C

actual

= C

nom

and the titer, t, is 1. If the concentration of the titrant is too high, t is > 1. If the concentration of the titrant is too low, t is <1.

The titer enables the titrator to calculate the results of your analyses corresponding to the actual concentration of the titrant used. It is therefore essential for you to accurately determine the actual concentration of the titrant against a reference substance before you first use it. The titrator can store the corresponding titer as a parameter for every titrant defined in the titrator. As long as the titer for a titrant has not been determined, the default value 1 is used. You can determine the titer yourself, enter the value for the titrant manually in the Setup menu, or to determine it through automatic titer determination with the titrator. Before doing this, you should make sure that a suitable standard is already stored in the titrator for the primary standard you want to use. If this is not the case, you must first define a new standard in the instrument. See "5.5.1 Adding a standard".

actual

nom

t =

Setup

24 METTLER TOLEDO DL15

Performing the titer determination from the Titrant setup

- Press Setup to open the Setup menu.

- Select "Titrant" using the arrow keys and press OK to confirm. The list of the titrants stored in the titrator appears.

- Select the titrant whose titer you want to determine.

- Press Modify.

- Select "Standard".

- Check whether the parameters of the selected standards match your primary standard substance. If this is not the case, press Modify and select the suitable standard from the list of standards stored in the titrator. Press OK to confirm your selection.

- Press Titer to open the titer determination function.

- A list of the methods appears. It shows only methods that use the titrant whose titer you want to determine.

- Select a suitable method using the arrow keys and start the titer determination by pressing Start.

- The titer determination is performed according to the conditions predefined for the method used. (See "6.3 Modifying a method"). The calculations from the method are ignored. The sample data from the method is replaced with default data.

- After the determination, you can view the statistics of the current sample series by pressing Stat..

- If the titer determined in this way is within the defined limits, press Save to accept the result of the titer determination (or the mean results if you have performed the titer determination several times).

- The date and time of the last titer determination are automatically updated.

- Quit the display that follows by pressing Esc. in order to prevent the date and time being set to 00-00-0000 and 00:00.

• It is also possible to perform the automatic titer determination from the Analysis menu. See "8.2 Starting a titer determination using the Run key"

• The concentration of a titrant can change after you have determined the titer. It is therefore absolutely essential to determine the titer at regular intervals in order to guarantee constant accuracy of the analysis results. The titrator can also generate a specific expiration date for each titrant, which requests the user to determine the titer again after a certain period.

Setup

METTLER TOLEDO DL15 25

5.3 Sensors

- Press Setup to open the Setup menu.

- Select "Sensors" using the arrow keys and press OK to confirm. The list of sensors

stored in the titrator appears.

Some sensors are already predefined in the titrator. You can add new sensors, change them or delete them from the list. For pH and ISE sensors you can also perform an automatic sensor calibration. You can define:

• mV sensors

• pH sensors

• ion selective sensors (ISE)

• polarized sensors

• To add a new sensor, you must change the parameters of one of the existing sen-

sors and then save it under a new name.

• A maximum of 20 sensors can be stored in the instrument.

5.3.1 Adding a sensor

To define a new sensor, proceed as follows:

- Press Setup to open the Setup menu.

- Select "Sensors" using the arrow keys and press OK to confirm. The list of sensors

stored in the titrator appears.

- Select an existing sensor from the list of sensors and press Modify.

- Change the name to the name of the new sensor you want to define.

- Change the parameters of the sensors according to the new sensor you want to

define. See "5.3.2 Modifying a sensor".

- Press Save to confirm your changes.

- The new sensor appears on the list.

• You can discard your changes at any time by pressing Esc to quit the selection. In

this case the sensor is not stored.

Setup

26 METTLER TOLEDO DL15

• Before using it for the first time, you must calibrate a newly defined pH or ISE sensor using the automatic calibration function (the Calib. key) if you have not already manually entered the slope and zero point. See "5.3.5 Sensor calibration from the sensor setup menu".

• In any case, first change the name of the sensor. Otherwise when you press Save, your changes will be effective for the existing sensor and no new sensor is stored in the instrument!

5.3.2 Modifying a sensor

- Press Setup to open the Setup menu.

- Select "Sensors" using the arrow keys and press OK to confirm. The list of sensors stored in the titrator appears.

- Select the sensor whose parameters you want to change from the list of sensors.

- Press Modify.

- The list of parameters of the selected sensor appears; the individual parameters can be selected and changed.

- Press Save to accept your changes and to quit the menu, or press Esc to discard your changes and quit the menu.

The following parameters can be changed, depending on the type of sensors:

Name The name of the sensor.

Input Depending on the type of sensor, either the pH or the pol. input

can be selected to connect the sensor. (see "4.2 Connections at the rear of the titrator")

Type This parameter lets you define the sensor type for sensors at the

pH input. There is a choice of pH, mV and ISE.

Unit A possible unit can be selected for the sensor (pH, mV or pX).