Flow Rate Of Chemicals Monitored By Industrial Scales

By Author: Mel Joelle
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Many situations require that certain chemicals be added into a process. This is the case where there are formulations to produce a specific final product. A number of different materials may need to be mixed together in a precise ratio. Industrial scales may be used for this purpose. Platform scales can be placed underneath each drum of material. As the material is pumped out of the drum, the digital scale can measure that amount. When the proper amount has been dispensed, the feed can be stopped. This may be controlled by the scale operator. Or the correct values can be programmed into the electronic scale, and it can automatically shut off its feeding device. The procedure can be duplicated for each ingredient that is being mixed into the final formulation.

Alternatively, the drum scale can be placed underneath the container holding the final product. Again, an operator can control valves and pumps to feed in each required ingredient. In a more automated facility, the industrial scale can accept a number of programmed values. As each value is reached, the feeding device for that ingredient can be automatically shut ...
... off, and the following ingredient feeder turned on.

In some cases, though, the material being added must be dispensed at a specific rate of flow. This may be the case if a particular ingredient can only be mixed in at a particular rate because of its viscosity. Or, the mixing process itself may generate heat that must be dispersed or gasses that must be removed. Certain applications are a continuous process, requiring each of the ingredients to be dispensed at the required rate.

Some of the most common applications that can benefit from measuring the flow rate are in water and waste water treatment plants. Many different chemicals must be added to the water for disinfecting purposes, chlorination and fluoridation. It is critical for public health and safety to dispense the proper amounts of these materials.

Some industrial scales may be used for this purpose. They must include a flow rate feature. Arlyn Scales produces a wide line of digital scales that include this capability, including drum scales, platform scales, floor scales, bench scales, and cylinder scales. The digital indicator can determine the flow rate in pounds per minute or pounds per hour. The user can also enter the specific density of the ingredient, so that the flow rate can also be shown in gallons per minute and gallons per hour.

In order to calculate an accurate flow rate, the scale must be able to measure the change in weight during measured time periods. If the flow rate is quite slow, the industrial scale will need a significant amount of time to accumulate a meaningful change in weight. If the flow rate is higher, less time is required. The sensitivity of the scale also determines how quickly it can calculate a flow rate. The greater the sensitivity, the quicker it will be able to show a good value for the flow rate. All of the Arlyn Scale models are able to measure weight with excellent sensitivity levels.

Another very useful feature is an alarm system that alerts users to an incorrect flow rate. The most obvious situation would be when the flow rate decreases to zero, as will happen if the material has been fully depleted from its drum. But there can also be problems if a line is clogged, or a variable valve is stuck in a fully closed or fully open position. A setpoint controller is available on the drum scales, cylinder scales and platform scales. It is usually programmed by the user to provide a visual and electrical signal when the weight in the drum falls below a particular level. This is a notification that the drum should be changed. But those electronic scales that include the flow control feature can also use the setpoint controller to program alarm levels for the flow rate. When the rate falls below a programmed value, a visual alarm and electrical signal are activated. The same can happen if the rate is greater than programmed.

These industrial scales are also available with communication capabilities. They may communicate with local computers through an RS-232 serial interface, a USB port, or an Ethernet connection. Alternatively, if the scale is connected into an Internet connected network, the amount of material remaining in the container, and the flow rate, can be monitored from any other internet connected computer.
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