What pressure is applied to a system after opening the cylinder valves during a triple evacuation?

In a triple evacuation process, the primary goal is to remove moisture and contaminants from a refrigeration system. After the cylinder valves are opened during this procedure, it's essential to introduce a slight pressure into the system to facilitate this evacuation process effectively.

Applying a pressure of 0 to 3 psig allows for the introduction of refrigerant vapor into the system without over-pressurizing it. This range of pressure is safe and sufficient to help push out air and non-condensables while avoiding any potential damage to the system components that could occur with higher pressures.

This low-pressure application also helps ensure that the vacuum can adequately pull out moisture, as having a controlled and low-pressure environment is crucial for effective moisture removal. Higher pressures could lead to inefficient evacuation and risks damaging sensitive components within the HVAC/R system.

By understanding that the goal is to lightly pressurize the system for proper scavenging of contaminants, it's clear why maintaining a range of 0 to 3 psig is the appropriate choice.