Vacuum Pump Time Calculator
Estimate evacuation time for proper system dehydration
System Parameters
Vacuum Pump
Target Vacuum
Estimated Results
Evacuation Process
Enter values to see breakdown
Evacuation Best Practices
Before Evacuation
- ✓ Verify system is leak-free (nitrogen pressure test 24+ hours)
- ✓ Change vacuum pump oil (if not fresh)
- ✓ Use large diameter hoses (3/8" minimum)
- ✓ Connect directly to system (bypass manifold if possible)
- ✓ Open all valves in refrigerant circuit
During Evacuation
- ✓ Use a digital micron gauge (not just pump gauge)
- ✓ Perform standing vacuum test (isolate pump, watch for rise)
- ✓ If vacuum rises, find leak or moisture source
- ✓ Consider triple evacuation for wet systems
Standing Vacuum Test
After reaching target, isolate pump and monitor for 10 minutes. Rise of <100 microns = acceptable. Rise of >500 microns = leak or moisture present.
Triple Evacuation
For contaminated systems: Evacuate → Break with dry nitrogen → Evacuate → Break with nitrogen → Final evacuation. Dramatically speeds moisture removal.
Vacuum Level Reference
| Microns | mmHg | inHg | Water Boiling Point | Application |
|---|---|---|---|---|
| 5,000 | 5.0 | 0.20 | 1°C (34°F) | Too high - not acceptable |
| 1,000 | 1.0 | 0.04 | -17°C (1°F) | Minimum acceptable |
| 500 | 0.5 | 0.02 | -24°C (-11°F) | Standard target |
| 300 | 0.3 | 0.01 | -29°C (-20°F) | Better practice |
| 200 | 0.2 | 0.008 | -34°C (-29°F) | Best practice |
Why microns matter: At lower vacuum levels, water boils at lower temperatures. To remove moisture from a system at 20°C (68°F), you need a vacuum below 17,530 microns. Lower is always better for thorough dehydration.