Micron to Dew Point Converter

Convert vacuum readings to moisture content and dew point

Vacuum Level Converter

1 micron = 1 μm Hg (micrometer of mercury)

Micron-Dew Point Reference Table

Microns (μ) Dew Point °C Dew Point °F Moisture (ppm) Quality
25,400 26.7 80 33,434 1" Hg - Not evacuated
5,000 0.8 33.4 6,578 Poor - Too much moisture
2,500 -8.9 16 3,289 Marginal
1,000 -19.4 -3 1,316 Acceptable minimum
500 -28.9 -20 658 Good - Industry standard
250 -37.2 -35 329 Very Good - R-410A systems
50 -50.0 -58 66 Excellent - POE oil systems
20 -56.7 -70 26 Deep vacuum

Target Vacuum Levels

  • R-22 500 microns (minimum 1,000)
  • R-410A 250-500 microns (POE oil is hygroscopic)
  • R-32 250-500 microns
  • R-454B 200-400 microns (A2L refrigerant)
  • VRF/VRV 200 microns or better

Decay Test Guidelines

  • After reaching target, isolate pump and wait 10-15 minutes
  • Rise of <100 microns = system is tight
  • Rise of 100-500 microns = check for moisture
  • Rise of >500 microns = leak present
  • Continuous slow rise indicates moisture outgassing

Important Notes

  • • POE and PVE oils are highly hygroscopic - absorb moisture from air quickly
  • • Never leave POE oil systems open to atmosphere longer than necessary
  • • Digital micron gauges are more accurate than analog compound gauges
  • • Vacuum pump oil should be changed regularly for best performance
  • • Core removal tools significantly reduce evacuation time
  • • Larger hoses (3/8" or 1/2") evacuate faster than standard 1/4" hoses