Metrohm 709 IC Pump User Manual

Page 37

4.2 Maintenance and servicing

709 IC Pump

To install a new piston seal

68 the special tool 73 is used:

•

First the new seal is inserted firmly in the recess of tool

73 by

hand (see Fig. 10B). The seal spring must be located on the

outside.

•

The tool

73 together with the seal is then inserted in the pump

head

18 and the seal pressed into the pump head recess

with the aid of tool

72 (see Fig. 10C).

The seal surface in the pump head

must not be damaged (avoid

contact with tool)!

5 Cleaning/replacement of inlet valve

and outlet

valve

Different valves are used depending on the pump version. In the

2.709.0010 IC Pump, the 6.2824.020 Inlet valve and the 6.2824.010

Outlet valve are built-in, in the metal-free 2.709.0110 IC Pump, the

6.2824.090 Inlet valve and the 6.2824.080 Outlet valve are built-in..

Contaminated or blocked valves are cleaned by rinsing with dist.

water, RBS solution or acetone. The rinsing effect can be

reinforced by brief treatment in an ultrasonic bath (max. 20 s; if

longer the sapphire sphere of the valve can be damaged).
If this does not have the desired effect, the valves can be

disassembled as shown in Fig. 11. The valve components are

pushed out with the aid of a syringe needle inserted through the

upper opening in the valve housing

74. The individual compo-

nents are rinsed with dist. water and/or acetone, and the sap-

phire sphere cleaned with a paper towel. The valve is then

reassembled in accordance with Fig. 11. The components of the

inlet and outlet valves are identical, they are distinguished only

by the positioning of the sapphire sleeve

77 and the ceramic

holder

79 (see Fig. 11).

Valves that fail to function faultlessly after such cleaning must be

replaced.
In the reinstallation of the inlet valve

69 or the outlet valve 70 on

no account must the two outwardly identical valves be inter-

changed. To determine which valve is which, note that the liquid

flows through the pump head from the bottom up. The flow

direction of the valves can be checked simply by blowing

through the clean valve. Both valves are installed with the black

face in the direction of the pump head (see Fig. 9).