Maintenance And Care; Cleaning The Instrument; Maintenance Of Electrodes - Mettler Toledo SevenDirect SD20 Benutzerhandbuch

Temperature Reading
Temperature
limit
Inactive
Active

6 Maintenance and Care

Do not open the housing of the instrument; it does not contain any parts that can be maintained, repaired or
replaced by the user. If you experience problems with your instrument, contact your authorized METTLER
TOLEDO dealer or service representative.

6.1 Cleaning the Instrument

NOTICE
Danger of damage to the instrument due to inappropriate cleaning agents!
The housing is made of acrylonitrile butadiene styrene/polycarbonate (ABS/PC). This material is
sensitive to some organic solvents, such as toluene, xylene and methyl ethyl ketone (MEK). If
liquids enter the housing they can damage the instrument.
1 Use only water and a mild detergent to clean the housing.
2 Wipe off any spills immediately.
The instrument is turned off and disconnected from the electrical outlet.
Clean the housing of the instrument using a cloth dampened with water and a mild detergent.
If you have questions about the compatibility of cleaning agents, contact your authorized METTLER TOLEDO
dealer or service representative.

6.2 Maintenance of electrodes

The instrument monitors the condition of the attached pH electrodes.
Slope: 95-105%
and offset: ± (0-20) mV
Electrode is in good condition
When cleaning, always follow the instructions in the manual of the electrodes used. Make sure the pH electrode
is always kept filled with the appropriate filling solution. For maximum accuracy, any filling solution that may
have "crept" and encrusted the outside of the electrode should be removed with deionized water. Always store
the electrode according to the manufacturer's instructions and do not allow it to dry out.
If the electrode slope falls rapidly, or if the response becomes sluggish, the following procedures may help. Try
one of the following, depending on your sample.
Problem
Fat or oil build-up
SevenDirect™ SD20
In progress
Within limit Out of limit
font: light blue
background: white
font: light blue font: red
background: white
Slope: 90-94%
or offset: ± (20-35) mV
Electrode needs cleaning
Endpoint reached
Within limit
font: white
background: dark blue background: light
font: white
background: green
Action
Either rinse the membrane with soap solution or acetone/ethanol
or shortly soak the tip of the electrode in warm water. When
rinsed with organic solvent, place the membrane overnight in
0.1 mol/L HCl.
Out of limit
blue
background: red
▶
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Slope: 85-89%
or offset: ± (>35) mV
Electrode is defective or too old
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