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Critical Standards for Specifying Sight Glasses

Sight glasses are highly engineered products. Although brands look alike, differences in their specs have tremendous importance for worker safety, sanitary processes, and maintenance costs. Here are the critical specs and standards for sight glass selection:

USP Type I Standard for Pharmaceutical Use
USP Type I glass is the most resistant to heat and chemical corrosion. To meet this standard, a sight glass must pass test procedures defined by USP29-661. USP standards require the use of Type 1 glass for many applications.

Many sight glasses on the market fail to meet this important standard, and some sight glasses are not even Type 2 or Type 3; rather they are non-parenteral, which means they should not be used in applications where chemical durability and heat shock are factors.

DIN 7079 Standard for Fused-Glass Sight Glasses in Metal Frames
The DIN 7079 standard for fused-glass sight glasses sets standards for fusion, thermal properties, strength, and chemical resistance. This is a stringent standard, and not all sight glasses can meet its specifications.

DIN 7080 Standard for Glass Quality
The DIN 7080 standard means the glass has passed tests for material strength, shock endurance, chemical resistance and compression. There is no reason not to insist on high this quality glass.

The ASME BPE (bio-processing equipment) Standard standardizes specifications for the design, manufacture and acceptance of vessels, piping and related accessories for use in equipment used in the biopharmaceutical industry. Some sight glasses do not meet ASME BPE standards which require the absence of crevices where glass meets metal.

Factory Mutual has defined standards that sight glasses should meet in order to provide safe operation. Use of FM approved products may in some cases reduce plant insurance costs.

L.J. Star’s METAGLAS® sight glasses meet all the critical standards. No wonder it is the number 1 selling sight glass, proven in thousands of installations.

Documentation Guarantee: L.J. Star will always provide third-party documentation of standards compliance and product performance claims.