Scales and balances are used in every area of modern life, from truck scales to pharmacy balances, and it’s important to understand their history. The weight of an object can’t be properly expressed by itself. A comparison must be made. Scales and balances express the resistance needed to maintain the object in equilibrium when other weight is applied.
If you do not have much previous experience in metrology, choosing a scale or balance to do your job can be daunting. The major parameters to consider are: what capacity (how much weight) do you require; what accuracy do you need (not just resolution); are you selling the things you weigh by their weight; and what can you afford to spend?
What can we say, with some degree of certainty, about the precision scales and analytical balances of tomorrow? They will have to meet or exceed the specifications of today’s balances. They will probably have a smaller footprint and be faster. They will still require a draft shield when weighing with 0.1 mg resolution.
Many people consider the terms weight and mass to be synonymous. They use the words interchangeably. And, in most cases, this isn’t really a problem Mass refers to an intrinsic property of an object. The mass of an object is a constant. Weight, on the other hand, is not a constant. Weight is the force created when mass is acted upon by a gravitational field. In fact, for the purposes of metrology, the Earth’s gravity has been defined as 9.80665 newtons.
How are these three things; the weight of an object, the location of that object, and the calibration of the scale used to weigh that object, all related? The one thing that remains constant about the object (provided it is not mechanically altered) is its mass. The mass of an object is the same any where on earth, or in space, or on the moon, or any other location. The simple equation, F = m x a, states that Force (F) on an object is equal to the product of the mass (m) of that object times the acceleration (a) to which it is subjected.
Using a scale or balance to count piece parts in industry for dispensing parts to production or taking inventory is an old and well established practice. Using a scale in a pharmacy to count pills is a recent event, and approval from The National Committee on Weights and Measures was a long time in coming. The practice of counting by weight was illegal in commerce until this one exception was made for counting pills in the pharmacy. The exception was made based upon the fact that the FDA applied tight weight controls on pill manufacturing. All scales that are used for pill counting in the pharmacy must be approved by NTEP to be sure they have the required accuracy and sensitivity for this application in order to be legal for trade.
There are a variety of paths that a modern Analytical Balance or Laboratory Scale can take between the manufacturer and the final customer (end user). This particular market segment has been global for a long time and people are very accustomed to the names of large European manufacturers. However, many more are being added as the emerging nations add new names to the list of manufacturers. Many U.S. suppliers have been acquired by large European manufacturers as they vie for domination of the market and better control of pricing within the market.
The design of a product has a great deal to do with the final quality of the product. The quality of the product has a great deal to do with the type of experience the user will have with the product. The user has a number of things to look for in determining whether or not they are buying a quality product, in this case a laboratory or analytical balance.
A history of compounding is truly a history of pharmacy. Modern compounding requires a pharmacist to prepare a medication, when in receipt of a valid prescription, by mixing, combining, or altering to or more ingredients in accordance with a recipe for a patient. Modern compounding requires an accurate pharmacy scale and a good relationship between the physician, the pharmacist, and the patient.
Historically, the Torsion Balance Company ( Torbal ) was inaugurated in the late nineteenth century. The technology which made the company unique was the use of taut bands in the classic Roberval suspension. This eliminated the effect of side and end loads, and is still in use in almost all scales and balances today. The company progressed and grew, primarily through sales in the pharmaceutical, medical, analytical and laboratory markets. It acquired the Christian Becker Company, a leading maker of analytical balances, early in the 20th Century. During World War II, the company devoted much of its manufacturing and technical expertise to devices used in the war effort.