Danfoss SGI / SGN Series

Danfoss sight glasses (SG, SGI, SGN and the SGR/SGRI/SGRN variants) are standard liquid-line fittings that give fast visual indication of two critical system conditions: refrigerant charge state (bubbles in the liquid line indicate flash gas from undercharge or restriction) and moisture content via a colour-indicating element.

The moisture indicator changes colour when moisture in the refrigerant exceeds safe limits — a yellow indication signals that the filter drier must be replaced. Mounted after the filter drier and ahead of the expansion valve, the sight glass is the simplest diagnostic window into system health, and standard practice pairs it with a DML/DCL filter drier.

Types available: Danfoss SG (plain sight glass, no indicator), SGI (flare connections with moisture indicator), SGN (solder ODF connections with moisture indicator), and the SGR, SGRI and SGRN variants. Supplied across the common line sizes in both flare and solder ODF. Send the line outside diameter and whether you want the moisture indicator, and we will confirm the code number.

Fit a sight glass when you are commissioning a system, chasing an undercharge, or replacing a filter drier — bubbles in the liquid line mean flash gas from undercharge or a restriction, and a yellow indicator means moisture in the circuit and a drier that needs changing.