Anschutz manometer

A frequently used simple mercury manometer which is employed for the measurement of pressure in the range 0.5-17 cm (6.6 to 226 mbar) is the U-tube design illustrated in Fig. 2.124 (Anschutz manometer, Gallenkamp). It consists of a U-tube charged with mercury and mounted in a wooden stand. The scale B, graduated in millimetres and sometimes made of mirror glass in order to eliminate errors due to parallax, is sited between the two arms and is movable. This... 

Safety note Do not allow air to rush into an Anschutz manometer, otherwise the mercury in the left-hand limb of the manometer will shoot up the tube and may break the glass at the top. 

A manometer to measure the pressure (vacuum) in the apparatus, since the boiling point of a liquid varies with pressure. Two types are in common use (Fig. 15.3) the Anschutz manometer, which gives a constant reading of the vacuum throughout the distillation, and the Vacustat , which is used to take a sample of the vacuum at a given instant. Vacustats are very accurate and are more often used in eombination with a rotary oil pump. 

Using thick-walled rubber pressure tubing, connect the water pump (via the anti-suck-back trap) to the three-way tap and then to the Anschutz manometer. Connect another piece of pressure tubing to the manometer but do not connect it to the pig for the moment. 

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