VWR VP 820 Manual Del Usuario página 12

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4. Carefully remove pump head / pump heads.
The magnetic valve of the drying system remains fitted in this
situation.
Change diaphragm
Replace the diaphragms of two-headed pumps consecutively
in order to ensure that the same number of diaphragm spacers
is used.
1. Push down one diaphragm until other diaphragm is pushed upwards
to its highest position.
2. Carefully unscrew this diaphragm (1) anti-clockwise using both
hands.
3. Replace spacer thick (2) and spacers thin (3) onto the screw thread
of the new diaphragm (same number and order).
4. Screw in the new diaphragm and tighten it by hand.
5. Complete steps 1 through 4 for the second pump head.
Change valve plates/sealings
Replacing the valve plates/sealings of two-headed pumps
consecutively.
1. At one pump head: Loosen screw (1) in the center of the top plate
(2).
2. Remove top plate (2) and head plate (3) from intermediate plate (5).
Valve plates/sealings (4) are visible
3. Remove old valve plate/sealings.
4. Clean intermediate plate (5) carefully (if there should be deposits in the
recesses in the intermediate plate).
5. Insert new valve plates/sealings (4) in the recesses in the intermediate
plate (5).
6. Carry out the steps 1 to 5 for the second pump head.
7. Dispose of the old diaphragm and valve plates/sealings properly.
Refitting pump head
1. At one pump head: Apply pressure all around the edge of the
diaphragm.
2. Place the intermediate plate (8) with valve plates/sealings on the
adapter in accordance with the felt-tip pen marking.
3. Place the head plate (6) on the intermediate plate (8) in the position
indicated by the guide pin (7).
4. Place the top plate (5) on the head plate (6) in accordance with the felt-
tip pen marking.
5. Gently tighten screws (4) in diagonal order.
6. Insert screw (1) with disk springs (2, 3) in the center of the top plate (5).
In doing so, make sure that the disk springs are arranged properly.
7. Screw in the screw (1) in the centre of the pump top plate (5) until it is
flush with the top plate, then screw one final half turn to tighten.
8. Carry out steps 1 to 7 for the second pump head.
9. Refit the pneumatic head connection: Place tube onto the connecting
part of the angle fitting, turn angle fitting to a straight position and
tighten the union nut.
Final steps
1. Reconnect suction and pressure line to the pump.
2. Reconnect system to the electricity.
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Fig. 7: Change diaphragm
Fig. 8: Change valve plates/sea-
lings
1
2
3
4
5
6
7
8
Fig. 9: Refitting pump head