Global Processing

When are fused glass/metal sight glasses appropriate in biopharm applications?

July 13, 2005

Myth: Fused glass/metal windows are only designed for safety. They are appropriate only for use in high pressure/vacuum, thermal shock, and high mechanical shock applications.

Fact: Although such demanding circumstances are ideal applications for MetaClamp ® sight glasses, they are beneficial in all sanitary applications. In addition to their inherent safety, they also have a longer service life, require little maintenance, seal better, are easier to clean, and are more durable.

Myth: MetaClamp sight glasses allow media to become trapped between the glass and metal, forming bacteria traps.

Fact: There is no space between the glass and metal components of a MetaClamp sight glass, only a surface transition that results when surfaces of differing hardness are polished.

Myth: Fused glass/metal sight glasses using soda-lime glass are appropriate for most low-pressure applications.

Fact: As standard, MetaClamp sight glasses are made of borosilicate glass to DIN 7080 for good reason. In addition to having less strength than borosilicate glass, soda lime is also more susceptible to corrosion, thermal shock, and high temperatures.

Myth: Fused glass/metal sight glasses have small bubbles and crevices along the glass/metal seam that create bacteria traps.

Fact: It is possible that tiny bubbles will develop at the transition from glass to metal in the manufacturing process when using either soda-lime glass or, to a lesser extent, borosilicate glass. But, in a MetaClamp sight glass such bubbles are inconsequential since they are quite small and few in number, and they will not be found at or near the surface. Also, MetaClamp sight glasses comply with DIN 7079 which dictates the allowable number and size of bubbles resulting from the manufacturing process.

Myth: MetaClamp sight windows are limited in that they cannot be electropolished.

Fact: All MetaClamp sight glasses can be electropolished to any desired finish.

Myth: Traceability can be a problem with fused glass/metal sight glasses.

Fact: This may be true of some sight glasses but not MetaClamp sight glasses. They are permanently marked with Heat Number, Material, Size, and Manufacture. Other markings are available upon request.

Myth: Compliance with USP Class VI is vital in many biopharm applications.

Fact: Not a myth, this is true! And MetaClamp sight glasses are fully compliant with USP Class VI, tested to confirm biocompatibility