Laboratory vacuum pumps N 8__.3 FT.40.18
Servicing
Translation of original Operating Instructions, English, KNF 121350-121429 11/18
27
6. Put the diaphragm spacer(s) (
7
) on the thread of the new
diaphragm.
7. Fit the new diaphragm (
6
): hold the connecting rod (
8
) with one
finger, and gently screw in (clockwise) the diaphragm with dia-
phragm spacers.
8. Turn the fan until the diaphragm is at the top dead centre.
Using a small screwdriver, between the housing and the outer
edge of the diaphragm, carefully lift the edge of the diaphragm
lightly upwards at one point. Now grip the edge of the dia-
phragm on opposite sides (do not overstretch the diaphragm!)
and tighten the diaphragm clock-wise.
9. Carry out steps 1 to 8 for the second pump head.
Changing valve plates/sealings
Replacing the valve plates/sealings of pump heads
consecutively.
1. Undo the two screws (
3
).
2. Separate the head plate (
10
) with top plate (
2
) from intermedi-
ate plate (
9
).
3. Remove the valve plates/sealings (
1
) from the intermediate
plate.
4. Check that the valve seats, the head plate and intermediate
plate are clean. If scratches, distortion, or corrosion are evident
on these parts they should be replaced.
5. Lay the new valve plates/sealings (
1
) in the recesses in the
intermediate plate. The valve plates/sealings for suction and
pressure sides are identical, as are upper and lower sides of
the valve plates/sealings.
6. Carry out steps 1 to 6 for the second pump head.
7. Dispose of the old diaphragms and valve plates/sealings
properly.
Refitting pump head
1. Turn the fan to bring the diaphragm (
6
) of one pump head to
medium position.
2. Place the intermediate plate (
9
), with valve plates/sealings (
1
),
on the housing, in the position indicated by the marking (M).
3. Place the head plate (
10
) on the intermediate plate (
9
) in the
position indicated by the marking (M).
4. Place top plate (
2
) in position and insert screws (
3
) with disk
springs (
4
), and tighten them until the screw heads are just ful-
ly seated (do not completely tighten them!).
Summary of Contents for N 820.3 FT.40.18
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