Servicing
Swing Piston Pumps NPK 25
14
Translation of original Operating and Installation Instructions, english, KNF 121581-121584 08/16
Prepatory step
1. Remove the front fan cover (Fig. 1/
3
, see page 6) of the pump
after loosening the four fixing screws.
Front fan is visible.
Removing pump head
1. Mark the position of head plate (
2
), intermediate plate (
6
) and
pump housing relatively to each other by a drawing line with a
felt-tip pen to ensure proper assembly.
2. Unscrew the four screws (
1
) and remove the head plate (
2
).
3. Remove the valve plate (
4
) from the intermediate plate (
6
).
4. Remove the intermediate plate (
6
).
5. Remove O-rings (
5
) from intermediate plate (
6
).
6. Remove O-rings (
3
) from head plate (
2
).
7. Check the intermediate plate (
6
) and head plate (
2
) for soiling
and damage. Clean the parts if necessary.
8. Contact KNF in case of roughness, scratches and corrosion.
Order and replace damaged parts.
9. Move the retainer plate (
9
) to the upper point by turning the
fan.
10. Pull cylinder (
13
) upwards.
11. Remove O-ring (
12
) from cylinder (
13
).
12. Hold on fan while loosening the countersunk screw (
7
) of
retainer plate (
9
).
13. Remove countersunk screw (
7
), O-Ring (
8
), retainer plate (
9
)
with piston seal (
10
).
14. Remove piston seal (
10
) from retainer plate (
9
).
15. Remove spacer(s) (
11
) from connecting rod (
14
).
16. Dispose of the old piston seal (
10
), valve plate (
4
), countersunk
screw (
7
) and O-rings properly.
Mounting pump head
1. Hold the connecting rod (
14
) from the front through the fan
opening, and replace the cylinder (
13
) on the pump housing.
2. Lay new O-ring (
12
) on cylinder (
13
).
3. Re-
assemble the “piston-assembly”:
a. Lay the new piston seal (
10
) on the retainer plate (
9
).
For orientation of piston seal (
10
) see fig. 6.
b. Fit new O-ring (
8
) onto new countersunk screw (
7
).
c. Push the new countersunk screw (
7
) with new O-ring (
8
)
through the retainer plate (
9
).
4. Fit the same number of washer(s) (
11
) as previously used on
connecting rod (
14
).
Fig. 5: NPK 25 AC / NPK 25 DC:
Parts of pump head
Fig. 6: Orientation of piston seal
(10) in relation to retainer plate (9)
