Sanhua SYJ28H51 Sight Glass – 3/4" ODF Solder, with Moisture Indicator, 46 bar

Sanhua SYJ28H51 is a 3/4" ODF solder sight glass installed in the liquid line of a refrigeration circuit. Its ring-type color indicator shows the moisture level in the system.

Shows Two Things at Once in the Liquid Line — Refrigerant Condition and Moisture Level

First task — refrigerant condition. When viewed through the glass, the liquid should appear clear. If bubbles are visible, either the charge is low or there is a restriction ahead of the expansion valve. This is the quickest way to check the charge in the field.

Second task — moisture. Moisture entering the circuit combines with the refrigerant and oil to produce acid; the acid first destroys the winding insulation and then the compressor. Moisture also freezes and blocks the line at the outlet of the expansion valve. When the indicator color changes from green to yellow, the filter drier is saturated — it is replaced before the compressor is damaged.

The body is brass, and sealing is provided by low-creep PTFE; since the indicator is bonded to the glass, surface contamination does not affect the reading.

Technical Specifications (Official Sanhua SYJ Series Datasheet)

• Connection: 3/4" ODF solder, same size at both ends
• Max. working pressure (PS): 4.6 MPa = 46 bar
• Medium temperature (TS): −50 … +80 °C | Ambient temperature: −50 … +80 °C
• Body: corrosion-resistant brass
• Sealing: low-creep PTFE — leak-free operation
• Indicator: ring-type moisture color indicator, bonded to the glass (prevents surface contamination)
• Passage: full port — low pressure loss
• Glass: wide-angle, high clarity — highly readable
• Certificate: PED 2014/68/EU Article 4.3 (Fluid Group 2) · ANSI-ASHRAE 34 Group A1
• Compatible refrigerants: R22 · R134a · R404A · R410A · R507 · R407C · R407A/F · R448A/R449A · R452A · R450A/R513A

• 🔧 Location: installed in the liquid line AFTER the filter drier. It can also be used in the suction line.
• 🔧 Mounting position: Sanhua recommends a vertical line. If it is to be fitted in a horizontal line, the glass must face upward and must not be tilted in any direction — with tilted mounting the indicator reads incorrectly.
• ⚠️ Brazing warning: wrap the body in a wet cloth when brazing. Excessive heat permanently damages both the PTFE seal and the color agent of the moisture indicator — the indicator will never read correctly again.
• Reading the color: GREEN = dry (system safe) · YELLOW = wet (filter drier saturated, replace it). The color change is not instantaneous; read it after waiting at least 12 hours with the system running.
• Bubbles do not always mean a low charge. A restriction ahead of the expansion valve, a blocked filter drier or insufficient subcooling also cause bubbles.
• Other options in the same size: SYJ19H51 and SYJ19H11 (3/4" solder) · flare versions are also available — with male/male and male/female (D/E) options.