Metrohm 807 Dosing Unit - Manual (Page 47)

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5 Troubleshooting
807 Dosing Unit
￭￭￭￭￭￭￭￭ 39
Problem Cause Remedy
Wear Replace dosing piston and cylinder.
[PREP] / [Preparing] is
not carried out or false
parameters- ￭ Carry out [PREP] / [Preparing]
￭ Correct tubing length and diameter.
No dosing takes
place at all Tubing connections are
blocked or dosing unit is
not assembled correctly. ￭ Check whether the dosing tip is blocked.
￭ Check whether the dosing tubing is con-
nected to the correct port.
￭ Check whether the dosing port is sealed off
with a stopper.
￭ Check whether the VENT port is sealed off
with a stopper (vacuum in the supply bot-
tle!). The VENT port must be open for pres-
sure compensation.
￭ Remove dosing drive and check whether
the dosing piston is connected to the dos-
ing drive. The piston stopper must be flush
with the upper side of the housing.
￭ Check whether the connection cable is
attached to the dosing drive.
Not possible to
rotate the stopcock Valve disc and distributor
disc stick to one another. Clean valve disc and distributor disc (see Chap-
ter 4.1.2, page 32).