SP Bel-Art Spinbar Teflon Polygon Magnetic Stirring Bar; 25 x 6mm, White, Pivot Ring (F37122-0025)

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Product details

• Product Dimensions ‏ : ‎ 4 x 3 x 0.75 inches; 0.16 Ounces
• Item model number ‏ : ‎ 371220025
• Date First Available ‏ : ‎ November 3, 2009
• Manufacturer ‏ : ‎ Bel-Art Products
• ASIN ‏ : ‎ B002VBW6J4
• Country of Origin ‏ : ‎ USA
• Domestic Shipping: Item can be shipped within U.S.
• International Shipping: This item can be shipped to select countries outside of the U.S. Learn More

• Best Sellers Rank: #97,878 in Industrial & Scientific (See Top 100 in Industrial & Scientific)
  • #14 in Lab Stirrer Bars
  • #85 in Lab Stirrers

Product Description

Size:1 x 1/4″ (25 x 6 mm) Size:1 x 1/4″ (25 x 6 mm) Plastic container surfaces are less prone to being scratched or marked by the spinning bar. Multifaceted surface transfers more torque to the liquid being stirred when compared to non-faceted cylindrical stir bars of the same size. Features center molded pivot ring for reduced friction and chattering. Research, industrial and healthcare professionals rely on SP Scienceware for their sample handling needs. Sold worldwide, Bel-Art and H-B Instrument brand laboratory supplies include over 5,000 items from safety wash bottles to fume hoods, thermometers, racks, desiccators, hydrometers, ice buckets, scoops and spoons. Custom calibration services, plastic molding, specialty coatings and wire manufacturing are also available. Wilmad-LabGlass brand laboratory glassware complements Bel-Art and H-B Instrument with over 7000 items including NMR and EPR consumables and specialty glassware, as well as custom fabrication for individual glassware, glass repair services and OEM glass parts. SP Scienceware is a division of Warminster, PA based SP Industries which also include SP Scientific laboratory, thermal management, and pharmaceutical production equipment and SP Ableware aids for daily living.

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From the manufacturer

Magnetic Stirring Bar Selection & Use

Magnetic stirring is used in a number of common laboratory procedures, yet the importance of selecting the best stirring bar for each particular application is often overlooked. The drive magnet, vessel shape, viscosity and abrasiveness of the materials should all be considered when choosing the size, shape and materials (coating and magnet) of the magnetic stirring bar in order to achieve effective, efficient stirring results.

First, let’s discuss magnetism. On the most basic level, we know that opposite poles attract. A magnetic stirrer has a drive magnet, generally a bar or U-shaped made of a metallic alloy or a ceramic which rotates powered by a drive motor. The magnetic poles of the drive magnet are typically about two inches apart in bench top models, and can be up to six inches apart in larger units used to mix 50 gallons of liquid solution. For optimum magnetic coupling the distance between the magnetic poles of the drive magnet and the length of the stirring bar should be equal. Bars too long or too short in proportion to the drive magnet will not have optimum coupling which is important to reduce spin-out.

Once a magnetic stirring bar has been placed in a container with solution, it should be positioned directly over the center of the drive magnet. The stirring speed should be increased slowly, until the desired vortex pattern is achieved. Should the magnetic stirring bar lose its coupling with the drive magnet because of the speed of the drive magnet, viscosity of the fluid, or an improperly selected stirring bar length, it is said to have ‘spun-out’.

Vertical distance between the drive magnet and the stirring bar should be kept to a minimum for the best coupling and stirring efficiency. Therefore, the containing vessel should be as thin as practical.

The selection of the shape of the magnetic stirring bar also influences the resulting vortex in that multi-sided shapes may be more efficient in moving solutions and certain shapes have been designed to provide a tailored fit in specialty vessels such as test tubes, cuvettes and spectrophotometer cells.

Magnetic stirring bars are generally made of ALNICO (an alloy of aluminum, nickel, iron and cobalt) magnets encapsulated in an FDA approved PTFE coating. In addition, magnetic stirring bars also use high energy magnetic materials, such as Samarium Cobalt which increases strength of coupling with a drive magnet and helps to reduce spinout when mixing viscous solutions or mixing at high speeds.

Newer to the market, the Bel-Art Products Spinfinity magnetic stirring bars, use ALNICO magnets encapsulated in plastic for increased durability in granular slurries.