When I heard the term Sight Glass, my first association was with a Spy Glass from a sweet flick movie where the good character used a spyglass to see far into the horizon. Little did I know that sight glasses are amazing devices that indeed are used to see into unknown worlds. In fact, it is by the virtue of a sight glass the unknown worlds become visible, understood and comfortably predictable.
A sight glass is an industrial device, hardly inspiring a conversation about a romantic movie, yet it inspires development of a lot of technology projects. Like bolts and nuts, sight glasses are staple industrial commodities taken for granted. As an engineer, I find them remarkably interesting; a sight glass is a perfect blend of dissimilar materials that work together as one when properly designed and fabricated. This is a challenging feat to create a glass window that holds against pressure, at high temperature, often in an aggressive chemistry. While a sight glass is a mechanically challenged device, its main purpose is to see through it, so the sight glass must be done in such a way as all the complexities of the design do not impede the view.
Advancements in material science offer new solutions for creating sight glasses for difficult applications. Our world has reached greater depth for energy exploration, finer wavelengths in lasers, we are getting closer to plasma inside their generators. We are surrounded by a lot of opportunities for new sight glass designs. The point of all of this a delicate balance of gloomy economy and booming opportunities in technology and engineering. I feel that the need to explore, discover the new, find growth will prevail. As far as sight glasses are involved, the world has created NPT, Metric, ASME, Conflat, all well engineered and field tested sight glasses, usually in stock, ready to purchase.