What is the approximate pressure for ammonia before reaching the trans-critical phase?

The approximate pressure for ammonia before reaching the trans-critical phase is best identified as 1,650 PSIA. In thermodynamics, the behavior of ammonia as a refrigerant is well-defined within its phase change characteristics. The trans-critical phase refers to the state where the refrigerant transitions from the subcritical to the supercritical state, which occurs at high pressures. For ammonia, this pressure point typically lies in the range mentioned, as it is significantly higher than the pressures seen in typical cooling applications. Therefore, knowing that ammonia has a critical pressure of about 1,200 PSIA (which is the point above which the refrigerant can no longer exist in the liquid state regardless of temperature), the assessment shows that pressures above this critical point will shift the ammonia into a supercritical state, making 1,650 PSIA a relevant figure as it precedes the transition into that region. Understanding the normal operating and critical conditions of ammonia helps set accurate expectations for its behavior in cooling cycles.