Servicing
Diaphragm pump N922 EX
34
Translation of Original Operation and Installation Instruction, english, KNF 313600 11/19
6. Screw the new diaphragm (6) onto the diaphragm support clockwise
and hand tighten.
If the zone diaphragm is overtightened, there is risk of the PTFE
coating detaching.
Replacing valve plate and seal
1. Remove the pressure plate (4) with the six screws (5) from the pump
head.
2. Loosen the screw (7) and remove it together with the washer (8).
3. Separate the head plate (3) from the intermediate plate (2).
Carefully set down the head plate to so as not to damage its sealing
edge.
4. Remove the valve plates/seals (9) from the intermediate plate (2).
5. Only for .29 versions:
Remove the O-ring (10) from the intermediate plate.
6. Check the valve seats, intermediate plate (2), head plate (3) and, if
necessary, O-ring groove for soiling and damage. Clean the parts if
necessary.
Contact KNF in the event of unevenness, scratches or corrosion. Order
and replace the damaged parts.
7. Inserting valve plate/seal:
Valve plates/seals are identical for the pressure and suction side;
the same applies for the top and bottom of the valve plates/seals.
Insert the new valve plates/seals (9) in the valve seats of the inter-
mediate plate (2).
8. By moving the valve plates/seals (9) sideways slightly, make sure that
the valve plates/seals (9) are centered in the valve seats of the inter-
mediate plate (2).
9. Only for .29 versions:
Insert the new O-ring (10).
10. Place the head plate (3) on the intermediate plate (2) according to the
locating pin (12) and the felt-tip pen marking.
11. Check the centering of the head plate (3) by means of a slight lateral
movement.
12. Connect the head plate (3) and the intermediate plate (2) to one an-
other by tightening the screw (7) with underlying washer (8) (tightening
torque: 100 Ncm).
13. Place the pressure plate (4) with the six screws (5) on the head plate
(3) and the intermediate plate (2) according to the felt-tip pen marking.
14. Properly dispose of the replaced diaphragm, valve plates/seals and, if
applicable, O-ring.
Mounting the pump head
1. Place the pump head on the housing according to the felt-tip pen mark-
ing.
2. Screw in the screws (5) and tighten them lightly crosswise.
3. Check for ease of movement of the pump by turning the counterweight.
4. Tighten the screws (5) crosswise (tightening torque: 450 Ncm).
5. Position the housing cover ( Fig. 7/1) and screw down with the four
Allen screws ( Fig. 7/2) (tightening torque: 15 Ncm).
Final steps
1. Reconnect the suction line and the pressure line to the pump.
