George Washington stated the need for weights and measures in the United States. Thomas Jefferson finalized the creation of weights and measures proposal to congress. John Adams was the President who signed the official act. Recently there was a Saturday Night Live episode showing George Washington talking to his troops about the need for weights and measures. During the SNL show, they brought to light many details that make weighing and measurement confusing to the public. Everyone today is touched in some way by this industry.
Early weights and measures were isolated to a particular region. Originally consumers bartered or traded for commerce and stayed local to where they lived. As commerce grew, the need for weights and measures grew. The government was protecting consumers to prevent fraud in the marketplace. In May of 1875, the United States along with sixteen other nations, signed the Treaty of the Meter. This treaty created the International Bureau of Weights and Measures (BIPM) under the authority of the General Conference on Weights and Measures (CGPM and the supervision of the International Committee for Weights and Measures (CIPM). This is where coordination of international metrology and systems of measurement takes place. This standardized weights and measures system was essential for trade. As commerce grew and consumers traveled further, we needed this system.
Imagine if you went to the market and one market measured in its own system of measurement and another did something totally different. How would the consumer know what he was paying for? Today, we may have different units of measurement like grams, ounces, or pounds, but there is a standard way to calculate from one unit to another.
The first scales were mechanical scales. They used pivots and bearings, had indicators or a beam. Mechanical scales were durable but operated slower. The operator would have to wait for the oscillation in the base to settle and read the display. It took practice to perfect the reading. In Handbook 44 (the industry standard for Commercial Applications), the mechanical scale reading at zero could be plus or minus one-half (1/2) scale division.
The load cell was invented in the 1900s. The load cell converts force such as tension or compression into an electrical signal. Load cells were used originally in the weighing industry along with the mechanical scale to create an electro-mechanical weighing device. By combining the mechanical scale with load cells, the industry was able to use a digital display (indicator) which improves the measurement process time, and the display was easier to read.
In the late 1900s the first load receiving elements were made with load cells. These fully electronic weighing systems were quickly adopted. Originally there were times where outside interferences like RFI, noise, or poor power lines created issues. Today, electronics have improved to provide protection against outside elements while these elements that exist have also been modified and improved. Today’s electronics are quick, stable, and dependable.
Display (or indicators) evolved from a simple display to many different types of displays. Originally displays consisted of multiple boards that connected by ribbon cables. These cables and multiple boards made trouble-shooting more complex. Today’s displays may consist of one multi-function board.
Manufacturers saw the need to add more capability to weighing equipment. The first was the need to provide documentation for the weight. Originally mechanical systems used recording elements that stamped the value. This evolved to electronic printers. The communications to printers originally were BCD (binary-coded decimal) which involved using a cable that contained 32 wires. Next came RS232C and 20 mA. With these new communications options, it was possible to add some distance between the indicator and a remote display or printer.
Options like a remote display are popular today and needed when there is a distance between the load-receiving device and the indicator. Handbook 44 specifies that if there is a distance between the weighing process and the consumer, both must be able to see the weight display and the measurement process. The remote display option allows the consumer to view the display.
Electronics continued to advance. Manufacturing processes continue to improve and there is a need to make improvements in processes. Scale indicators added features like digital inputs and outputs, 4-20mA output, multiple serial (RS232C) ports, Ethernet, and communication protocols to operate with PLC inputs and outputs.
Indicators developed in the 2000s to operate in their own language protocols to add prompts to displays to help the operators in complex processes. Indicators and load-receiving devices are utilized in every industry. It is said that everything that is made is weighed at some point!
As products added capabilities the training for employees became essential. Originally with mechanical scales scale technicians needed to understand mechanics and be able to pick up test weights to validate the weight. Now, scale technicians need to understand electronics, mechanical system operations, be able to troubleshoot Ethernet, RS232C, and analog equipment. Older weighing equipment is still viable and being used in many areas. This industry has expanded to encompass all diverse types of knowledge.
Today, an application may be as simple as a base and display, or as complicated as a system controlling an entire weigh-out system with RFID tags, Wi-Fi communications sending databased and electronic copies of transactions, and a printer for the customer’s documentation. The scale industry needs to stay up to date with requirements for all the industries that the equipment is being utilized. In industries where washdown is required, we have stainless steel NEMA 4X or IP rated equipment as well as sanitary certifications. In applications where the product being weighed is explosive or subject to intrinsically safe restrictions, we have equipment that meets these requirements. Explosive equipment will contain any explosion inside the enclosure. The intrinsically safe equipment will not emit any voltage that would cause a fire or explosion.
Handbook 44 is the Scale-person’s guide to regulations here in the United States. It has been adopted by all states in some form or fashion. Every state has its own weights and measures departments that have additional regulations. Some states have testing that requires all states to have licensed technicians. The ISWM (International Society of Weights and Measures) has a test to allow recognition for technicians who study and learn the industry. After passing the test, this technician is now a Certified Weighing Technician. The NCWM (National Conference of Weights and Measures) has a new program that provides tests for service technicians. This test when completed provides a Certified Registered Technician certificate. These two programs acknowledge scale technicians that have worked, studied, and succeeded in the weighing industry!
For a commercial application (legal-for-trade) a Class III device shall not display more than 10 000 divisions. What this means is that a scale that is:
“(a) To weights and measures and weighing and measuring devices used or employed:
(1) in establishing the size, quantity, extent, area, composition (limited to meat and poultry), constituent values (limited to grain), or measurement of quantities, things, produce, or articles for distribution or consumption, purchased, offered, or submitted for sale, hire, or award;
(2) when assessing a fee for the use of the equipment to determine a weight or measure;
(3) in determining the basis of an award using count, weight, or measure; or
(4) in computing any basic charge or payment for services rendered on the basis of weight or measure. (Amended 2008 and 2022)
(b) To any accessory attached to or used in connection with a commercial weighing or measuring device when such accessory is so designed that its operation affects the accuracy of the device.” (Excerpt from NIST Handbook 44)
Once the scale dealer has determined that a scale falls in a Commercial Application, he must follow the Handbook 44 guidelines. The manufacturer of the device determines the Class of the scale. The classes are Class I (Precision Balances), Class II (Balances), Class III (Industrial Weighing), Class IIIL (Vehicle Scales) and Class IV (Wheel Load weighers for highway weights enforcement). In Handbook 44, Table 3 states that an industrial scale may not have more than 10,000 scale divisions. A scale division is the smallest value that the device may display. The total number is the device capacity divided by the division size and the result is the number of scale divisions.
Many customers ask for more resolution than is permissible by Handbook 44. The customer is thinking that he will be more accurate, however scales have mechanical and electronic restrictions. The repeatability and linearity of the device are taken into consideration in setting the limitations for commercial applications in the marketplace.
Scales are used everywhere and in every industry. They are needed to keep the marketplace fair and equitable. The industry in the United States allows trade worldwide since we follow the Essentials of Traceability required for weighing and measuring.
