Diaphragm Vacuum Pumps UN012, UN024, UN036_I
Servicing
16
a.) Preparatory step
1. Disconnect the pump from the power supply; check that the
pump is electrically dead and secure this.
2. Release the screws on the underside of the head insulation
(see fig. 2) and lift the head insulation out upwards.
3. For .11 designs only (pumps with thermostatically-regulated
head heating) and .26 designs (pumps with heated heads;
electronically controlled): Remote the strain relief from the
underside of the head insulation or from the compressor
housing (N036.0).
b.) Removing pump head
For pumps with heating inset (.11 and .26 designs): The heating
inset remains fitted in the head plate.
1. Mark the position of support ring (
1
), intermediate plate (
3
),
and head plate (
4
) relative to each other by a drawing line with
a felt-tip marker. This is to ensure that the parts will be
reassembled in correct position at a later stage.
2. Release the cap nuts (
6
) and remove them together with the
spring washers (
5
).
The spring washers are fitted in order to maintain the tension
of the wave diaphragm right across the temperature range of
the pump.
3. Remove head plate (
4
).
4. Remove intermediate plate (
3
).
5. Remove the valve plates (
11
) and O-rings (
10
) from the
intermediate plate (
3
).
c)
Changing diaphragm
1. Cut around the circumference of the wave diaphragm (
2
) (cut
clamping disc (
7
) free - to facilitate loosening).
2. Release the clamping disc (
7
) by turning it counter-clockwise
with a pin wrench or a clamping disc wrench. To counter hold,
insert open-ended wrench above the upper insulating plate and
onto the connecting rod extensions (
9
).
Take care to ensure that the shims do not slip under the
diaphragm support (
8
).
3. Remove wave diaphragm (
2
).
4. Check that all parts are free from dirt and clean them if
necessary (see section
6.
Cleaning
).
5. Slide a new wave diaphragm (
2)
onto the threaded bolt of the
retainer plate (
7
).
6. Screw the clamping disc (
7
) with wave diaphragm (
2
) into the
connection rod extension (
9
); to tighten the retainer plate, use
the wrench for clamping disc/the pin wrench to turn it firmly
clockwise.
