Vacuum Pump System SC 920G
Servicing
Translation of original Operating Instructions, English, KNF 121308-121311 07/18
37
Change valve plates
1. Mark the position of head plate (
9
) and intermediate plate (
10
)
relative to each other by a drawing line with a felt-tip pen. This
helps avoid incorrect assembly later.
2. Mark the position of head plate (
9
) and intermediate plate (
13
)
relative to each other by two drawing lines with a felt-tip pen.
3. Mark the position of head plate (
9
) and intermediate plate (
14
)
relative to each other by three drawing lines with a felt-tip pen.
4. Undo the three screws (
6
) in head plate (
9
) and remove head
plate from intermediate plates (
10
), (
13
) and (
14
).
5. Remove valve plates (
12
) and O-rings (
11
) from intermediate
plates (
10
), (
13
) and (
14
).
Instead of lying on intermediate plate, O-rings could stick to
head plate (
9
).
6. Lay the new valve plates (
12
) and the new O-rings (
11
) on the
intermediate plates (
10
), (
13
) and (
14
).
Upper and lower sides of the valve plates are identical. For
correct position see fig. 17.
7. Dispose of the old diaphragms and valve plates/sealings
properly.
Mount pump head
1. Place head plate (
9
) on intermediate plates (
10
), (
13
) and (
14
)
in the position indicated by the drawing lines.
At the front edge the three intermediate plates must lie in a line
on which head plate is placed flushly.
2. Tighten the three screws (
6
) of head plate (
9
) carefully slightly
hand-tight (tightening torque: 0.6 Nm).
For position and orientation of disk spring (
7
) and washer (
8
) of
screw (
6
) see fig. 18.
3. Place head cover (
3
) on pump housing (
17
).
4. Tighten the nine screws (
2
) of head cover (
3
) slightly in the
first instance. Start with the screws of medium pump stage,
then tighten the screws on the right, and finally on the left.
5. Now, tighten the screws (
2
) firmly (tightening torque: 6 Nm);
tighten the center screws first, then continue outward.
If the screws are stiff to turn, the intermediate plates do not lie
in a line at front edge, or intermediate plates and head plate
are not placed flushly (see step 1).
6. Remount the covers (
4
).
7. Tighten the two screws (
1
) on the head cover (tightening
torque: 5 Nm).
Fig. 17: Position of valve plates (12)
Fig. 18: Position and orientation of
disk spring (7) and washer (8) at
screw (6)
