Improperly specified, installed or maintained sight glasses can represent the weakest link in a processing system. The wrong glass or materials used will limit observation, require extra maintenance and replacements, and even fail under pressure with catastrophic results – since glass can fracture at 5 miles/second.
safe sight glass
Since it was developed in the 1970s, Metaglas has been known as the safest sight glass in the world. A number of chemical and manufacturing companies collaborated to create Metaglas, and to establish the standard with which it complies and by which all other sight glass is measured, a standard now called DIN7079.