A lab stirrer mixes substances for a variety of academic, research, or industrial applications such as solutions in chemistry and biology and food and beverage production. There are two basic types of stirrers: magnetic or overhead. Magnetic stirrers are ideal for smaller volumes and low-viscosity solutions, have no moving external parts, are considered easier to clean than overhead models, and do not need lubricants which can contaminate the solution being mixed. Magnetic stirrers have a rotating magnetic field that causes a separate magnetic stir bar, when immersed in a solution, to spin and stir the solution. They usually have a plate on a base and either an internal or external controller. Some models have multiple stirring positions to stir more than one vessel at once, and in some the plate is also a hot plate for heating the solution while stirring. They can be submerged in water and used inside closed vessels or systems, such as incubators. Overhead stirrers are ideal for large volumes and high-viscosity solutions in open vessels, and usually have a stirring blade and a drive shaft typically made of stainless steel or a chemically-resistant polymer, a controller, and a motor. This type of stirrer often needs more space than a magnetic stirrer, and can be more difficult to set up and to clean afterwards. However, by changing the stirrer blade shape, they offer control over how a substance is stirred. For example, certain shapes are suitable for high-speed stirring of low viscosity substances, while other shapes are suitable for low-speed stirring of high viscosity substances. Both magnetic and overhead stirrers come in analog and digital models, and a variety of configurations and sizes.
Benchmark Scientific manufactures sterilization and temperature control equipment, centrifuges and mixers, and other laboratory products. The company, founded in 2008, is headquartered in South Plainfield, NJ.