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There are also a wide variety of different methods for filling these drums. In the simplest situations, an operator may manually control a fill valve, shutting off the flow as the level appears to be reaching the top. Or, the valve could be on a timer. As long as the flow rate remains fairly constant, this could be a reasonable, although not very accurate method of filling a drum.
The most accurate way to fill drums is to use a drum scale. This type of industrial scale is designed to easily allow drums to be loaded onto and off of the scale platform. Therefore, it is important to provide a very low profile. High quality electronic scales, such as those from Arlyn Scales, use platforms that are as low as 1 7/8” off of the floor. With such a low platform, the ramps for the scale may be quite short, minimizing the overall footprint of the scale.
Filling scales must be very rugged. Often, a drum must be put onto a scale by hand. Or if a forklift or drum cart is used, it may accidentally impact the scale from the side. This can damage the load cells in the scales. The most rugged scales provide stainless steel load cells, instead of aluminum or plated steel. As an added advantage, this type of load cell is more resistant to spills and chemical exposure.
The digital scales that are used for filling may provide setpoint outputs that are used to control filling devices. When the weight in the container reaches that value, an electrical signal will be provided, and an indicator will light on the front panel of the scale. That signal can power a solid state relay, that will in turn shut off the filling device. Often, two different setpoints will be used to achieve greater accuracy. The first will be programmed to a weight that is near the target value. The filling operation may proceed quickly to that point. Then, the fill rate may be slowed down to a trickle rate. The second setpoint will be the desired final weight, where the fill is completely shut.
This type of industrial scale may also be used for simple batching operations, where there are a number of different ingredients. In this case, different setpoint values are used for each ingredient. As the first level is reached, the setpoint output will shut down the fill for the first ingredient, and will start the second. Each additional setpoint in turn will control the next material. Some electronic scales that are designed for this type of operation, such as the Arlyn platform scales, floor scales and drum scales, may control as many as eight different ingredients. Furthermore, the formulas may be stored in memory. This allow the operator to recall from memory the material that they are formulating. The Arlyn digital scales will store more than one hundred different formulas.
Batching scales should also have the ability to report their data back into a computer system. While RS-232 connections have been the industry standard for many years, newer scales are offering Universal Serial Bus (USB) and Ethernet protocols for more universal connection. Filling scales provided by Arlyn Scales include a choice of each of these methods. If necessary, a number of electronic scales may be wired together in a local network. Usually, the data is collected into an Excel spreadsheet or an Access database table. There are also software utilities provided to enter the data into the users custom Windows based software program.
If an Ethernet connection is preferred, the scale can connect into an existing network in the facility. This provides a method of accessing the data from any Internet connected computer. This is useful for collecting data remotely. With appropriate software, it can also provide a means for controlling the scales from a different location.
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