Weighing is an important part of many laboratory experiments and can be used for a wide variety of tasks. Whether it’s preparing chemicals for reactions or measuring the amount of a solid in a volumetric flask, precision is paramount.
It’s important to understand what can contribute to weighing errors. Read on to learn more about how to reduce them.
Level Measurement
Level measurement is done in large elevated storage tanks & silos for liquids & solids to know inventory & control the same. This can be discontinuous like sensing when the level is at a specific point value (point level detection). Level switches are used for this purpose which will generate an open or closed contact based on the set point. There are also continuous type of sensors like ultrasonic which works by sending a sound wave into the vessel & measuring the time taken for it to hit the process material & reflect back which gives the level.
Weight-based level instruments measure the total weight of a vessel with its contents – so they do not depend on height to determine process level and are inherently linear for bulk materials with constant density. This is the most popular way to measure level for solids & liquids. It requires a sensor that can be attached to the base of the tank and detect the weight (such as load cells) without coming into contact with the process material.
Inventory Measurement
Inventory control is an important function for most manufacturing processes. Knowing how much product you have on hand and what’s selling is crucial to developing a successful selling plan. Weight measurement instrumentation offers an objective, fast and accurate method of tracking inventory.
Level or inventory measurement by weighing is superior to volumetric technologies in tanks and silos. Weighing measures the amount of material in a container regardless of tank design, distribution or cavities, foam, bridging, internal mechanical bracing and temperature, making it ideal for measuring corrosive materials or operating in a harsh environment.
Many industrial processes use intermediate bulk containers (IBCs) for dispensing materials or blending ingredients. High resolution and fast update rates are needed to meet these demands. In a loss-of-weight application, IBCs are suspended from load cells to weigh the amount of raw materials that enter or are dispensed. The resulting weight data is used to open and close the IBC discharge gates in a filling or dispensing process.
Batch Weighing
Weigh batching is a process used to weigh, transfer and dispense bulk powders and granules from one container to another. Often, this is done to fulfill product recipe specifications and quality requirements. For instance, mixing 1:1:2 concrete mix requires precise ingredient measurements to ensure consistency in every batch.
A weighing system can be either sequential (gain-in-weight) or loss-of-weight, depending on how your plant receives and stores bulk materials. For example, if you store your material in silos that are impractical to mount on load cells, then a gain-in-weight system is appropriate.
When weighing samples, always use clean gloves or face masks to prevent hand grease from entering the weighing chamber and influencing the reading. Additionally, it is important to keep the weighing area clear from vents and heating/cooling systems that could disrupt the mass calibration. This will help to avoid erroneous weight readings due to air currents or temperature fluctuations around the balance.
Process Control
In manufacturing and production processes it is often necessary to monitor process variables and ensure that product meets or exceeds pre-determined specifications. Whether these are minimum and maximum limits for the property of a material or a range within which a specified quality attribute should fall, high-precision weighing can provide accurate, quick, repeatable, fail-safe and non-destructive monitoring.
Adding weight to control critical in-process controls enables the operation of a plant in a more consistent manner, improving operational performance and reducing waste. This can lead to more precise feed rates, reduced “give away” of product and underfills that risk regulatory non-compliance.
Capturing the right type of data is essential to the success of any process control application. Weighing systems offer the ability to send this data via a digital weight indicator to PLC’s and remote displays. Our local digital weight indicators come in a variety of sizes and color options and can be mounted on or off the scale with the proper mounting hardware.