According to independent laboratory tests conducted by a division of West Pharmaceutical Services, a type of glass widely offered as the equivalent of borosilicate glass and said to be appropriate for both pharmaceutical and general processing use, including critical sight glasses and prestressed sight glass elements, is actually general purpose soda-lime glass.
The product is Boro Plus™ glass, offered by J.M. Canty, Inc. in its Fuseview™ brand sight glasses. While J.M. Canty’s published technical specifications indicate that Boro Plus glass contains up to five percent boric oxide (B2O3), in fact the independent test shows that it contains no detectable boric oxide whatsoever, making it indistinguishable from common soda lime glass. According to the Glass Engineering Handbook (McGraw-Hill, 1984), true borosilicate glass contains 11 percent boric oxide. Boric oxide is the key ingredient that gives borosilicate glass superior performance to soda lime glass, in terms of temperature, thermal shock and chemical resistance. Boro Plus glass specifications are to be found on an interior page of the J.M. Canty website.
What’s more, the independent test lab classified Boro Plus glass according to United States Pharmacopoeia (USP) Standards as “Non-Parenteral,” the lowest grade type of glass defined by USP. According to the USP Standard, this is defined as general purpose glass suited for non-parenteral applications where chemical durability and heat shock are not factors. Unlike products that have passed test procedures defined by USP29-661 for USP Type I glass, Boro Plus glass failed to meet this important standard and did not even qualify as USP Type II or Type III, according to the lab test results.
A copy of the independent laboratory tests, including methodology and full results, is available upon request via e-mail at view@LJStar.com or by phone from the L.J. Star Applications Engineering Department at 330-405-3040.
To obtain additional information on borosilicate glass or on fused glass sight glass technology in general, contact L.J. Star Incorporated, P.O. Box 1116, Twinsburg, OH 44087. Phone: 330-405-3040. Fax: 330-405-3070. Email: view@ljstar.com. Website: www.ljstar.com/pubs/9.htm.
Boro Plus™ and Fuseview™ are trademarks of J.M. Canty Inc.
Note to Editors: The "2" and "3" in "B2O3" should be subscript.