What could you expect to happen to the operating pressures if a hermetic system is low on refrigerant?

In a hermetic system that is low on refrigerant, both the head and suction pressures would decrease. This is primarily because refrigerant is essential for maintaining the necessary pressure levels for proper operation. The ammonia vapor in the system is what allows for the heat exchange to occur, and when there is insufficient refrigerant, the ability to absorb and reject heat is compromised.

When the refrigerant level drops, there is less refrigerant to vaporize in the evaporator, leading to a reduction in the suction pressure. This lower suction pressure means the compressor is not able to draw in enough vapor, resulting in a subsequent drop in head pressure as well. As the system operates with inadequate refrigerant, it cannot maintain the designed pressure levels, leading to decreased performance overall. This reduction in both head and suction pressures ultimately affects the efficiency and effectiveness of the cooling process.