014L0006, Danfoss, Sight Glass. Type - SGP 1/2 RN High Pressure Sight Glass with socket connections, Ambient temperature: –50 °C to +80 °C. Max. working pressure: PS/MWP = 52 bar. SGP RN is a socket type sight glass for non-flammable HFC refrigerants. Indicates too high moisture content in the refrigeration system, lack of subcooling or refrigerant deficiency.