Metrohm 940 Professional IC Vario ONE/ChS/HPG - Manual (Page 80)

5.8 Servicing the high-pressure pump
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940 Professional IC Vario ONE/ChS/HPG (2.940.1240)
Figure 20 Components of the piston cartridge
1 Piston cartridge screw 2 Retaining washer
3 Zirconium oxide piston (6.2824.070) 4 Spring retainer
5 Spring (6.2824.060) 6 Inner plastic sleeve
Protects from metallic abrasion.
7 Piston cartridge 8 Backup ring
2 Cleaning the parts of the piston cartridge
￭ If the zirconium oxide piston has become contaminated due to
abrasion or deposits, then clean it using a fine abrasive cleaning
powder, rinse it using ultrapure water until it is free of particles
and dry it.
The zirconium oxide piston has to be replaced if it is heavily conta-
minated or scratched.
￭ Rinse the other parts of the piston and dry with a lint-free cloth.
3 Putting the piston cartridge together
￭ Insert the inner plastic sleeve, the spring and the spring retainer
into the piston cartridge.
￭ Slide the zirconium oxide piston carefully into the piston cartridge
until its tip emerges from the small opening of the piston car-
tridge.
￭ Attach the screw and tighten it by hand.
4 Reinserting the piston cartridge
Screw the assembled piston cartridge back into the pump head and
tighten, first by hand, then also using an adjustable wrench by
approx. 15°.
Clean the second piston cartridge in the same way.
Mounting the pump head
Accessories For this step you need the following accessories: