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Material properties
Manual vacuum pump with bell jar and manometer
Ref : 251 009
The device consists of a practically unbreakable transparent plastic vacuum chamber bell
jar firmly fitted with a vacuum gauge and a dual shut-off valve. The bell jar is placed on a
white plastic mounting plate consisting of a built-in pump and a retention valve.
The airtight joint of the bell jar to the base is done with a rubber ring inserted in a groove
on the base. The bell jar can be used in complete safety as soon as it is placed on the
rubber ring (do not use seal grease).
At the top of the bell jar is a double action valve. The flush-mounted red button can be
pulled to let in small amounts of air into the bell jar. By unscrewing the valve completely,
the large opening is freed for connecting other devices and instruments using its sleeve.
The vacuum valve located on the mounting plate is covered with a brass nozzle which,
once the bell jar is removed, can receive a rubber tube that can be connected either to an
independent mounting plate (Magdebourg hemispheres experiment) or a device that needs
to be vacuumized (Dutch tears).
In this case the air input is obtained by unscrewing the nozzle slightly. To remove the tube
it is recommended that the nozzle be completely unscrewed and the rubber be removed to
avoid applying extra stress on the plastic threading.
The vacuum gauge consists of a relative pressure graduated scale of 0 to - 600 mm Hg.
For example, if the air from the device is evacuated till the red line marking - 250, the
pressure in the bell jar will be about 760*- 250 = 510 mm Hg i.e. 0.67 atmosphere.
ENGLISH
1 – Air input valve
2. - Operating button to unscrew the valve
3 - Manometer
4 – Bell jar
5 – Vacuum valve nozzle
6 – Pump handle
7 - Base
8 – Rubber foot
3
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