In a refrigeration system say that the pressure is negative or that the system is under vacuum when the value of the relative pressure in the system is less than atmospheric pressure.
• The atmospheric pressure equals 1 atm, 760 mm Hg, 760 Torr, M.C.A. 10.33, 14.696 psi 1.0133 bar, 1,033 kgf / cm2 or 29.92 inHg. Any value situated below these is considered void.
