Weight Indicators Information
Weight indicators are digital or analog display devices that indicate the weight of an object located on a connected scale. The weight and measurements standards are created and maintained by the National Conference on Weights and Measures (NCWM). Weight indicators are used in commercial and industrial applications to display the weight of products of various sizes. The devices offer a number of display variations to match the requirements of their many applications—from uncomplicated truck scales to complex process automation solutions.
The use of basic scales measuring relative weight dates back to prehistoric times, with the earliest example discovered in modern-day Pakistan and dating to as early as 2400 B.C. In ancient models, the balance of the scales was the only indication of weight. Spring scales with analog displays began to emerge in the 17th century and were in frequent use by the mid-19th century. In particular, the postal industry created a high demand for analog display devices to increase the efficiency of postal workers. Modern digital weight indicators, including those for large-scale applications, began to emerge in the 1940s.
Weight indicators are available with a wide variety of features designed for specialized applications. However, the types of devices are less extensive concerning their primary function. Weight indicators are display devices calibrated to work with a weight scale system and vary in type by a digital or an analog readout. Other variations include wireless functionality and distinct compliance requirements that meet government and industry guidelines.
Conventional weight indicators are designed for industries such as trucking, aviation, shipping, food, chemical, energy and volatile materials manufacturing.
Weight indicators do not perform the electronic weighing of an object. Instead, the devices convert the weight measured by a spring, balance or electronic scale into an analog or digital readout. With digital readout devices, weight indicators operate like a computer with a central processing unit, operating software, data input and output, a display screen and a local operator interface.
Typical devices classify products by type. Weight indicators are grouped in accordance with their features.
Several features of weight indicators include:
- Durable, weatherproof casing
- Washdown enclosures
- Size of the digital readout (important due to the many applications requiring users to record the weight measurement from a distance)
- Light Emitting Diode (LED) Display
- Configurable analog to digital measurement rate
- Programmable ticket formats
- Full numeric keypad
- Three-stage digital filtering
- Mounting options—some weight indicators are mounted into a panel while others are designed for a stand-alone housing
Numerous weight indicators are optimized for particular forms of weighing. These include providing readouts from truck scales or functioning as a weight-based admixture dispensing system for concrete. Various indicators work automatically for use in unmanned weight terminals as well as units equipped with keypads or more advanced user interfaces. The additional features of advanced user interfaces provide more control to account for climate and unique material variations.
Indicators designed with oversized displays are seen at distances of up to 50 feet or more. Industrial and marine weight indicators feature rugged stainless steel enclosures made to operate in extreme environments. Materials avoid rust, corrosion and degrading effects caused by excessive heat and wet conditions. The enclosures are water proof or water resistant, making them washdown safe.
There are a wide variety of commercial and industrial applications for weight indicators. The weight scale coupled with the device or the distinct object being weighed defines its use. Commercial and industrial functions include the following:
- Bench scale applications
- Floor scale applications
- Tank or hopper scale applications
- Overhead track scale applications
- Truck scale or other transfer station applications
- Ready mix and concrete products dispensing applications
- Weigh house applications such as landfills or recycling centers
- Weigh lock applications (used in weighing canal barges)
- Tax, postage, freight and other cost levying applications
- Industrial process control applications
- Mining applications
- Aviation applications
- Oceanography applications
Each industry requires precise features of weight indicators. Matching features and manufacturer specifications for the job ensures proper readings and optimum performance.
Typical specifications of weight indicators include:
- The maximum weight output (an important consideration for use with scales that weigh large and heavy objects
- Load cell compatibility and other device compatibility measures
- Housing type
- Primary power source or alternate power source options
- Display type to meet size, brightness and clarity requirements
The interior of weight indicators includes electronic components and solid-state devices similar to those found in a computer. These materials normalize the flow of electricity and store, process and transmit data necessary for display. Circuitry comprises of resistors, transistors, diodes, memory chips and various processing units that work together to perform the functions of the indicator. The electronics are silicon based with tin, silver or gold leads connecting them to main circuit boards. Circuit boards are manufactured from fiberglass and plastics. Several wires and controller ribbon cables made of flexible rubber and plastic work to connect displays and send input data and output data.
Base units, springs and other mechanical pieces consist of metals such as stainless steel, durable plastics or polycarbonate materials.
The majority of weight indicators are appropriate for general-purpose weighing uses. However, certain applications require a device with tailored features to make sure it is suitable for the job. If the application involves weighing massive objects, choose an indicator with a high maximum weight display. For harsh outdoor conditions, there are many models with durable, washdown enclosures. Some devices are optimized for highly specialized uses like weight-based admixture dispensing.
Calibration and standards for weight indicators depend on which piece of equipment is being used. Each device must be calibrated to the weight scale system it operates with. Based on the weighing application the devices are designed to work with, weight indicators each have their own calibration and standards. Consult manufacturer’s guidelines to determine the calibration and standards requirements.