Final answer:
The minimum evacuation level when opening a system with POE oil is typically 500 microns, which must be held to ensure removal of moisture and non-condensables before charging the system.
Step-by-step explanation:
When a system using POE oil has been opened to atmosphere, it is essential to achieve and hold a minimum evacuation level to ensure that moisture and non-condensables are removed before the system is charged with refrigerant.
The minimum evacuation level commonly recommended is 500 microns (0.5 mmHg), which should be maintained for a suitable duration to verify that the system is properly evacuated and free of leaks.
To ensure proper dehydration and the removal of air, pulling a low vacuum is not sufficient; the evacuation must reach and hold the specific level of 500 microns, sometimes even lower depending on the system specifications.
Any higher level could result in inadequate removal of contaminants, which can degrade the performance of the HVAC system and potentially lead to component failures.
The minimum evacuation level that should be achieved and held before charging a system using POE oil is 500 microns of Hg. Evacuation is the process of removing air and moisture from the system to create a vacuum. Holding the evacuation level for at least 15 minutes is recommended.