P 2.1L user manual V6840, version 3.6
34
Maintenance and Care
Check Valves
Dirty check valves do not open and close properly. They cause pressure
fluctuations and irregular flow. If it is impossible to clean the check valves,
replace the whole unit.
Removing the Check Valves
Prerequisite
The pump head has been purged.
The capillaries have been removed.
The pump head has been dismounted.
Tools
Open-end wrench, sizes 10, 17
Next steps
You can either replace or clean the check valves.
Cleaning the Check Valve
The check valves are not disassembled for cleaning but they are cleaned
as a unit.
1. Put the valve in a beaker with solvent e. g. isopropanol.
2. Put the beaker in an ultrasonic bath for at least 10 minutes.
Installing the Check Valves
Prerequisite
The pump head has been purged.
The capillaries have been removed.
The pump head has been dismounted.
Tools
Open-end wrench, sizes 10, 17
Device defect
Damage to the pump head caused by overtightened capillary fittings.
Note the torque of the fittings.
Note:
PEEK fittings can withstand pressures up to 400 bar for 1/16" and
200 bar for 1/8".
Torque
Pump head stainless steel
Torque for inlet and outlet fitting
100 ml
15 Nm
250 ml
15 Nm
500 ml
12 Nm
1000 ml
12 Nm
Process
Figure
1. Unscrew the outlet fittings
1
.
2. Remove the check valve
2
.
3. Unscrew the inlet fittings
3
.
4. Remove the check valve.
Fig. 33
Removing the check valve
2
1
3
