Mettler Toledo GA42 Operations Instructions download pdf (Page 31)

METTLER TOLEDO DL36 29

11.3 Greasing the glass joints

– Turn the stopper/electrode/drying tube of the titration cell about once a week to check their

contact and to prevent them from sticking.

– Apply a very thin coating of grease if the contact (tightness) is no longer assured.

Notice: If an execessive amount of grease is applied, it could enter the titration cell and

increase the drift owing to the moisture it contains!

11.4 Changing the septum

– Change the septum of the injection port at frequent intervals. As old septums can easily

break, air can enter the titration cell and increase the drift.

11.5 Changing the silica gel

You should change the silica gel as soon as it starts turning pink.

– Unscrew the cover.

– Change the silica gel and screw the cover back on.

11.6 Changing the reagents

Switch the DL36 off and place it in a fume hood! Never inhale the vapors of

Karl Fischer reagents and avoid skin contact! The reagents could hazard

your health.

1. Catholyte

You should change the catholyte when

• the capacity limit is reached (see Section 8.1),

• the drift is too high (>10 µg/min) or the status "Stable" is no longer reached,

• the membrane is contaminated.

Changing the catholyte at regular intervals avoids high drift values and measurement errors.

– Siphon off the catholyte using the polyethylene bottle.

– Add 5 mL catholyte using a syringe (up to lower mark on the titration cell).

Notice: After the change, select Setup 1 and enter 0 for "C.Capacity". This sets the value of

the summed electric current (converted to mg H

O) of the catholyte to zero (see

Section 8.1).

WARNING

Maintenance and servicing

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Mettler Toledo GA42 Operations Instructions Page 31