A standard gauge pressure of 160-185 psi applies to which of the following?

• A. Laboratory vacuum
• B. Laboratory air
• C. Instrument air
• D. Non-medical air

Answer: (C)

Instrument air is the dry, oil-free compressed air used to power and operate pneumatic instrumentation and medical devices. It’s kept at a relatively high supply pressure so that regulators, filters, and long piping runs don’t drop the pressure below what equipment needs during peak flow. The typical gauge pressure of 160–185 psi matches the standard instrument air supply in many hospital systems, making it the best fit for this question.

Laboratory vacuum involves negative pressure, not positive gauge pressure. Laboratory air and non-medical air aren’t standardized for the high, clean, instrument-grade supply required by medical instrumentation, so they don’t fit the same role or pressure characteristics as instrument air.