Selecting a Triple Beam Balance on Amazon.com
A triple beam balance, also called a triple beam scale, is the simplest type of balance, and uses a lever and slide to indicate measurement. A balance is a measuring instrument that determines object mass relative to a known standard, while a scale uses a spring to measure object weight. Sometimes called a mechanical balance, a triple beam balance uses three beams, each with a sliding weight (also called rider or poise weight) that are moved across the beam to determine the mass of a specimen. Some triple beam balances can hold an additional counterweight to extend the capacity of the balance. Triple beam balances are manually zeroed before each use.
A triple beam balance usually has a pan that holds the specimen to be weighed. The pan is balanced on a fulcrum by the weights on the three beams. Double-pan mechanical balances are used for comparative weighing operations; that is, finding the difference in mass between two specimens. Specimen pans are often constructed of corrosion-resistant materials for long-term use and durability. Disposable, one-time use pans can be used to protect and extend the life of the balance pan. Some triple beam scales also have a hook that holds a specimen under the pan to measure weight or specific gravity.
Triple beam balances range in accuracy and precision and are used for rough weighing operations and classroom experiments to highly technical research applications. High precision triple-beam balances are calibrated using calibration weights. Because of their durability and cost effectiveness, triple beam balances are commonly used in classrooms and educational settings. Features to take into consideration when purchasing a triple beam balance include capacity and capacity extension, durability, pan material, weight and specific gravity measurement capability, and security features, such as the ability of the balance to be locked against theft or unauthorized use.