Weighing processes can be a key element in a variety of lab workflows. They help ensure accurate and consistent results, which are critical for any operation.

Before you start weighing, prepare your workspace by cleaning the area and ensuring that the equipment is calibrated and ready for use. Make sure that all necessary materials are gathered, including containers and gloves.

Types of Weighing Equipment

Choosing the type of weighing equipment to use depends on what you need it for. For example, an analytical balance is precision weighing instrument used in activities like chemical testing and drug preparation. These instruments are sensitive and require a draft-free location on a solid bench to operate properly. They should be gently loaded and placed and dials turned slowly to avoid shock loads. Regular calibration with a standard weight will improve accuracy.

Medical weighing equipment needs to be extremely accurate and easy to clean, particularly in areas that are regularly touched by people with infectious diseases or conditions. This requires specialized scales that are both highly precise and sanitary to ensure accuracy and facilitative of patient care.

Whether it’s a simple scale or a check-weigher on your conveyor system, COOPER Instruments & Systems can help you select the proper weighing modules for your application. We have load cell technologies to offer including strain gauge, force motor, or digital with options for local displays, PLC outputs and data transfer via ethernet, USB, RS-232, 0-10 V or 4-20 mA (other protocols on request). Choose the technology that best fits your needs.

Weighing Methods

Weighing methods are the processes that allow for accurate measurement of materials. Depending on the application and precision required, different techniques may be used.

One common method of determining the fill level in tanks or silos is gravimetric weighing. This involves measuring the weight of bulk solids, independent of grain size and density. This technique is ideal for industrial and manufacturing applications.

Another common weighing method is based on spring scales. These operate using Hooke’s law, where a spring stretches or compresses to produce an estimate of the gravitational force. Regardless of the type of weighing scale, it is important to maintain good laboratory practices to minimize sources of error.

These include keeping the weighing area free from air currents and maintaining thermal equilibrium within the room. Also, it is important to avoid touching or handling standard weights and objects that have been weighed. This can leave grease or oily residue that affects the measurement.

Weighing Accuracy

Inaccurate weighing can throw off the entire production process and cost companies money. To ensure accuracy, it is important to keep four factors in mind.

Resolution

Resolution is the number of intervals (or increments) or divisions that a weighing instrument can resolve, or the granularity of a measurement. It is determined by the weighing equipment, and is affected by the type of weight used and the amount of sensitivity.

Creep

A weighing system may experience creep, a change in the output from the load cell over time. This can be caused by long-term stacking of objects or vibrations from nearby equipment that the scale’s load cells pick up and interpret as weight.

Vibration

Vibration from equipment or from people leaning on the balance can cause misinterpretation by the scale’s load cells and cause inaccurate readings. It is recommended to isolate the weighing system from vibration sources and use weighing instruments with built-in vibration filters. The weighing area should be kept clean of dust, oil and moisture to avoid additional interference with the readings.

Installation

Weighing is a vital part of the industrial and manufacturing process. Whether it is measuring ingredients to bake a cake or determining the contents of tanks, silos and hoppers, precise quantification of matter allows for better control and more efficient use of materials, equipment and resources.

The correct mechanical installation of the weighing system is critical to its operation and accuracy. When the weight indicator is set to zero, a force must be applied and removed to check that it returns perfectly to zero.

The HBK SafeLOCKTM feature immobilizes the weigh module during installation without the need for dead stands or dummy load cells. This prevents accidental overload and helps you mount the tank scale correctly without compromising safety. This makes your installation process faster and easier and ensures accurate operation of the tank scale after commissioning. Using this feature also allows you to minimize the number of components in the weighing system. This in turn reduces maintenance costs and the risk of downtime.