Mettler Toledo MP220, MP225 Installation Manual

1

Installation

1. Unpack the meter, power supply, electrode,
electrode arm, buffer sachets, Guide Book and
calibration certificate. Keep the calibration
certificate in a safe place.

2. Check the power supply unit is the correct
voltage for your local supply. If it is not, contact
your distributor.

3. Attach the electrode arm to the left or righthand
side of the meter:

a. Turn the meter upside down and seat the

dome of the electrode arm base into the left
or righthand meter recess.

b. Insert and tighten the fixing screw.
c. Turn the meter and base the right way up

and locate the electrode arm onto the base
fixing post. Press down to snap into place.

Input and Output Connections

MP220 Rear Panel

power supply
unit socket

combination
electrode socket

automatic temperature
compensation probe socket

2

Display

stability/auto endpoint
indicator

electrode
condition
shown
here

prog. menu icons shown
here (and data transfer
icon - MP225 only)

temperature,
electrode
offset/slope
shown here

memory,
cal and
error
number
shown here

automatic or
manual
temperature
compensation
indicator

power supply
unit socket

pH or
combination
electrode socket

data output
socket

recorder output
socket

reference
electrode
socket

Input and Output Connections (continued)

MP225 Rear Panel

1. Disconnect the shorting clip from the pH socket
and retain it by clipping it over the socket.

2. Connect the electrode to the pH socket. If you
are using an electrode incorporating ATC
connect the other lead to the ATC socket.

3. If you are using a separate ATC probe connect it
to the ATC socket.

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

automatic temperature
compensation probe
socket

3

3. Repeat steps 1 and 2 using other buffers for a
2 point (or 3 point - MP225 only) calibration.

Electrode Condition Indicator

95.0 - 105.0% 90.0 - 94.9% 85.0 - 89.9%
electrode in electrode electrode
good needs needs
condition cleaning conditioning

n When you press Cal the pH buffer you selected for

cal 1 (Program Menu) is displayed for 2 seconds, and
then the meter starts measuring. If you want to use
another pH buffer (choice of 3) press Cal again. Press
Cal repeatedly to exit the calibration routine.

n The decimal point flashes during calibration

measurement. When the electrode output
has stabilized the stability indicator appears.

Manual endpoint - press Read to endpoint.
Auto endpoint - the meter automatically endpoints.

n When a calibration has endpointed you can press

Mode to display the absolute mV value and tempera­ture of the buffer. The display reverts to the buffer and
E0 values, or buffer and slope values for a 2 point (or 3
point - MP225 only) calibration after 2 seconds.

buffer

Calibrating

1. 1-point calibration

Example

Use auto endpoint or
to freeze the reading.

2. Rinse the electrode and blot dry

to return to sample measurement, or
continue with step 3 for further cal points

↓ 2 seconds

4

n If you press Mode to select pH or mV mode the meter

begins measuring immediately. You will not need to
press Read to start the reading.

n The decimal point flashes during sample

measurement. When the electrode output
has stabilized the stability indicator appears.

Manual endpoint - press Read to endpoint.
Auto endpoint - the meter automatically endpoints.

n If you have the RS232 cable connected to the Data

socket (MP225 only), sample data is transmitted at
endpoint.

Measuring Samples

1. Select pH or mV mode

2. Measure sample

Use auto endpoint or
to freeze the reading.

3. Rinse, blot and store the electrode.

5

Operating Hints

n Remove the wetting cap from the end of the

electrode and the rubber cap from the fill hole (if
fitted) before using the electrode.

n Calibrate using buffers with values that bracket

that of the sample. With a new pH electrode, or
after maintenance, we recommend you use a
buffer close to pH 7 for the first calibration point.

n For greatest accuracy, buffers and samples

should be at the same temperature.

n Do not use solutions after the expiry date.
n When transferring the electrode from one

solution to another, rinse it with distilled water
and blot dry with tissue paper - do not wipe the
electrode as this may cause polarization and
slow response.

n When you select the calibration buffers

(Program Menu), set the buffer you will use
most frequently for 1-point calibrations as cal 1
and the one you will use most frequently for the
second calibration point as cal 2, and for the
MP225, the one you will use most frequently for
the third calibration point as cal 3.