Flanged DIN 25 PN 30 Sight Glass, Smooth Pressure Side
Where process volume is undistributed by the viewport. Notice the sapphire window is mounted flush with the metal housing on the process side. This flanged window conforms to DIN 25 PN 30 standard. Pressure rating is 30 bar. Validated operating temperature range is -20°C to +375°C. Materials of construction are 316L stainless, C-axis sapphire window, and Inconel (Alloy 718) metal seal, Silver plated for hermetic compliance. The flange required a gasket between the flat side of the process chamber and the inner side.
Figure 1: Flanged DIN 25 PN 30 Sight Glass, Smooth Pressure Side
For threaded flush designs, take a look at SAE sight glasses: Precisely Positioned, Perfectly Invisible: The Engineering Behind Flush SAE Sight Glasses