Low pressure steam (with saturation temperature between 105 to 120°C) is usually used in the vacuum evaporators, which normally employ a vacuum of about _______________ mm Hg (referred to a 760 mm mercury barometer)?
Correct answer: C. 650
- A. 250
- B. 450
- C. 650
- D. 750
Explanation
A vacuum of 650 mm Hg corresponds to an absolute pressure of about 110 mm Hg when atmospheric pressure is 760 mm Hg. This low absolute pressure gives an evaporation temperature compatible with low-pressure steam at 105 to 120°C.
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