If you have a pressure reading of 30 psi absolute, what would it be in gauge pressure at sea level?

To convert absolute pressure to gauge pressure, you need to subtract the atmospheric pressure from the absolute reading. At sea level, atmospheric pressure is typically around 14.7 psi.

Given an absolute pressure reading of 30 psi, the calculation for gauge pressure would involve taking the absolute pressure and subtracting the atmospheric pressure:

30 psi (absolute) - 14.7 psi (atmospheric) = 15.3 psi (gauge pressure).

This conversion is essential in many practical applications, as gauge pressure reflects the pressure in a system above ambient atmospheric pressure, which is often the pressure measurement most relevant in operational scenarios. Understanding this distinction can help millwrights and technicians make appropriate decisions regarding equipment design, maintenance, and safety. This is why the answer of 15.3 psi accurately represents the gauge pressure at sea level corresponding to the given absolute pressure reading of 30 psi.