Laboratory glassware is even more complicated than which beer glass is appropriate for a craft brew. After all, drinking an IPA from a pilsner glass won’t ruin an experiment! Let’s take a look at the classifications of lab glassware.
What is Glassware in a laboratory?
From a lab standpoint, laboratory glassware encompasses items like beakers, funnels, graduated cylinders, flasks, test tubes and bottles. They may be used for a variety of tasks, including heating, measuring and mixing solutions. In this post, we’ll concentrate on volumetric glassware.
What’s the Difference Between Class A and Class B Glassware?
Class A glassware is typically manufactured from Borosilicate, while Class B is usually made from Soda-lime glass.
Made from a mixture of silica and boric oxide (B2O3), Borosilicate boasts a low melting point. Soda-lime glass is a relatively inexpensive, reasonably hard glass often used for glassware for labs, as well as food and beverages. Soda-lime glass – also commonly found in windowpanes – accounts for about 90 percent of manufactured glass.
Better suited for storing solutions, higher-accuracy Class A glassware provides better heat and chemical resistance. Class A maintains its accuracy level over a longer working lifetime, eliminating the need for more-frequent replacing.
Class B glassware offers the same basic design as Class A, but with lower tolerances and therefore, lower accuracy. It also doesn’t hold up as well against chemicals, so it’s not recommended for prolonged exposure.
What Determines Which Laboratory Glassware You Use to Measure?
Because Borosilicate doesn’t expand as much upon heating, flasks or beakers made from Class A glassware would be the better choice for measuring if you frequently apply direct heat.
If your glassware won’t be heated directly or isn’t heated to higher temperatures (like Petri dishes), Class B should suffice.
What’s the Best Laboratory Glassware for Measuring?
Strictly from an accuracy point-of-view, Class A would certainly be the best option since it retains accuracy longer. Sometimes a lower accuracy may be acceptable, so for general purposes, Class B would suffice.
Regardless of which you choose, eventually all lab glassware requires recalibration. Per ASTM 542 and ISO 4787 international standards, volumetric flasks need to be recalibrated every five (Soda-lime) to 10 years (Borosilicate).
Glassware subject to temperatures higher than 150°C or frequently used with strong acids or basses should be recalibrated sooner. If you notice chemical corrosion, immediately recalibrate or replace the glassware.
Two of the most common methods for calibrating glassware are volume transfer from automatic pipettes and gravimetric calibration (which uses an electronic balance in conjunction with distilled water, deionized water, or a combination of reverse osmosis with deionization).
Sonic Supply offers a wide range of lab glassware from manufacturers such as United Scientific and Eisco Scientific. If you have any questions or need help selecting the glassware for your lab, call or email us. We’re here to help!