KNF LABOPORT N820.18 EX Operating Instructions Manual page 105

Chemically-resistant Laboratory pump N820.18 EX / N840.18 EX
Translation of Original Operating Instruction, KNF 317428-317425 05/21
Replacing the valve plates/seals
On the pump, the valve plates/seals (4) are replaced suc-
cessively.
1. Remove the head cover (3) from the intermediate plate
(6).
2. Remove the old valve plates/seals (4).
3. Carefully clean the intermediate plate (6) (if there are de-
posits on it).
4. Insert the new valve plates/seals (4) into the correspond-
ing seats on the intermediate plate (6).
5. Perform steps 1 – 4 for the second pump head.
6. Dispose of the old diaphragm (7) and valve plates/seals
(4) properly.
7. Insert the connection tube (10/Fig. 10) into the head cover
(3).
Fitting the pump head
1. Move the diaphragms (7) to the center position.
2. Press on the entire perimeter of the diaphragm (7). Only
press on the diaphragm (7) on one pump head.
3. Place the intermediate plate (6) with valve plates/seals (4)
on the mount according to the pencil line.
4. Place the head cover (3) on the intermediate plate (6) in
line with the locating pin (5).
5. Place the pressure plate (2) on the head cover according
to the pencil line.
6. Tighten the screws in a crosswise pattern (tightening
torque: N820: 4 Nm; N840: 5 Nm).
7. Tighten the screw (1) in the center of the pressure plates
(tightening torque: 1 Nm).
8. Perform steps 1 to 7 for the second pump head.
9. Place the pump heads (consisting of head cover (3), inter-
mediate plate (6) with valve plates/seals (4) and pressure
plate (2)) together with the connection tube on the pump
housing according to the pencil line.
10. Mount the handle cover (3/Fig. 8).
Servicing
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