Metrohm 700 Dosino - Manual (Page 39)

3.4 Troubleshooting / Problems
700 Dosino, Instructions for Use
33
The whole system is blocked.
Possible cause:
• The Dosino or control instrument is in an exceptional
faulty condition.
⇒ Check cable connections.
⇒ Switch control instrument off and on again.
⇒ Remove dosing drive from dosing unit. With the instrument
switched on check whether the drive carrier can be rotated.
– If yes then the dosing drive is faulty.
– If no then dismantle the dosing unit. Clean the black stop-
cock washer in the cylinder base, see page 29.
3.4.2 Dosing unit
Air bubbles in cylinder or dosing tubing
Possible causes:
• Leaking connections.
⇒ Check the tubing ends, in particular that of the aspiration tub-
ing.
⇒ Tighten all tubing connections manually.
⇒ Check whether the housing is properly locked. If necessary
remove the housing and then put it back on again.
• The reagent releases a lot of gas, i.e. dissolved air forms
bubbles.
⇒ Carry out PREP.
⇒ Lower the filling speed.
⇒ If necessary degas the reagent ultrasonically.
• Wear and tear.
⇒ Replace piston and/or cylinder.
• PREP not carried out or incorrect parameters.
⇒ Carry out PREP.
⇒ Correct tubing lengths and diameters.
Stopcock washer and distributor disk stick together
Possible cause:
• Precipitation of crystals from the reagent.
⇒ Clean the stopcock washer and distributor disk, see page 29.