The Source Selection IPT consists of standing members from the NAVAIR Acquisition Policy and Processes Department, AIR-2.1, AIR-4.10E, Logistics Management Integration Department, and a AIR-11.0 Senior Attorney, with AIR-4.10E and AIR-2.1 as the Co-Chairs.
9.2.7.1 Basic Definitions Critical temperature (T c)The maximum temperature at which a gas can be converted into a liquid by an increase inpressure. Critical pressure (p c)The minimum pressure which would suffice to liquefy a substance at its criticaltemperature. Above the critical pressure, increasing the temperature will not cause a fluidto vaporize to give a two-phase system.
what you mean is gage pressure, which refers to the pressure difference to a reference pressure. In most cases the gage is open to atmosphere. so you reference pressure is 1 atm (or 14.7 psi). so if your gage pressure is - 1 psi, you have 13.7 psi actual pressure. Negative to atmosphere.