Question 1

How is vacuum measured?

Accepted Answer

Low vacuum: 1-100 mbar. Medium: 1-10⁻³ mbar. High: 10⁻³-10⁻⁷ mbar. Ultra-high: <10⁻⁷ mbar.

Question 2

What is perfect vacuum?

Accepted Answer

Zero pressure - impossible to achieve. Best lab vacuum: ~10⁻¹² mbar. Interstellar space: ~10⁻¹⁴ mbar.

Question 3

What pressure units do different industries use?

Accepted Answer

PSI in US/UK automotive and HVAC. Bar/kPa in European engineering. mmHg/torr in medicine. Atmospheres in diving and altitude.

Question 4

Is gauge pressure different from absolute pressure?

Accepted Answer

Yes! Gauge pressure reads 0 at atmospheric pressure. Absolute pressure adds atmospheric (~14.7 psi). Vacuum gauge shows negative gauge pressure.

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