Sight Glass Function, Moisture Indicator & Installation Position
Sight glass is fitted on liquid line after filter drier; technician observes liquid state and moisture condition of refrigerant. Clear liquid without bubbles: normal full liquid supply to expansion valve; continuous bubbles mean insufficient refrigerant or flash gas. Built-in chemical indicator changes color according to water content in refrigerant, the most convenient on-site moisture detection method. Color standard: green = dry qualified; yellow = excessive moisture, need replace filter drier and vacuum again. Sight glass cannot be installed near heat source; high temperature causes flash gas and misjudgment of liquid shortage. Xiteliduo sight glass supports R404A, R507, R448A, R449A, compatible with POE oil system. Even green indicator does not guarantee zero moisture; it only means moisture is below safe threshold for this refrigerant. Sight glass blockage or oil film covering glass will block observation; replace if cannot see internal state clearly. For multi-circuit rack system, each independent circuit should be equipped with separate sight glass for troubleshooting. Refrigeration maintenance & repair company combines sight glass reading with superheat, subcooling data to judge system charge.
FAQ
- What is the normal state in sight glass? Stable clear liquid, no continuous bubbles.
- What color means moisture exceed limit? Yellow.
- What color means dry and qualified? Green.
- What does continuous bubble in sight glass usually indicate? Refrigerant shortage or flash gas generation.
- Where to install sight glass? Liquid line after filter drier.
- Can one sight glass serve multiple refrigeration circuits? Not recommended; separate sight glass per circuit.
- Will high ambient temperature cause false bubble signal? Yes, heat causes flash gas.
- Does green indicator represent zero moisture in system? No, moisture is just within safe range.
