Description: Proper System Evacuation as Close to -29.92 Inches of Vacuum (HG) at Sea Level is Critical to Provide a Clean Dry System along with Proper Flushing Techniques. When working with an A/C Service Vacuum Pump Single Stage 3CFM, do not rely on a gauge set or time alone, and the use of a Micron Gauge is recommended for best practice to ensure proper evacuation levels.