Sanhua SYJ19H51 Sight Glass – 3/4" ODF Brazed, with Moisture Indicator, 46 bar

Sanhua SYJ19H51 is a 3/4" (19.05 mm) ODF brazed sight glass fitted in the liquid line of the refrigeration circuit. Its ring-type color indicator shows the moisture level in the system.

Shows Two Things at Once in the Liquid Line — The State of the Refrigerant and the Moisture Level

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

Second function — moisture. Moisture entering the circuit combines with the refrigerant and oil to produce acid; the acid destroys first 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, sealing is provided by low-creep PTFE; because the indicator is bonded to the glass, surface contamination does not affect the reading.

Technical Specifications (Official Sanhua SYJ Series Datasheet)

• Max. working pressure (PS): 4.6 MPa = 46 bar
• Media 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
• Certification: 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

• 🔧 Installation location: fitted 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 on 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 while brazing. Excessive heat permanently damages both the PTFE seal and the color agent of the moisture indicator — the indicator will never read correctly again.
• Color reading: GREEN = dry (system safe) · YELLOW = wet (filter drier saturated, replace it). The color change is not instantaneous; wait at least 12 hours with the system running before reading.
• Bubbles are not always a sign of low charge. A restriction ahead of the expansion valve, a blocked filter drier or insufficient subcooling also cause bubbles. First check the pressure drop ahead of the sight glass.

• Other version of the same size in our catalog: SYJ19H11 (3/4" brazed). Flare versions are also available — with male/male and male/female (D/E) options.