Many manufacturing processes require the addition of water in precise but differing amounts depending on the recipe under process. In these situations, batch control can be implemented with relatively little expense using an electromagnetic flowmeter. If a device with onboard intelligence is installed, the process manager is able to achieve recipe automation with very high accuracy.
This intelligence should include, at the very least, volumetric flow capability and programmable outputs. An economical and time saving option would be to install an electromagnetic flowmeter with on-board programmable relays. Such meters can be installed on most standard pipe sizes and pipe materials to measure not only water, but the multitude of conductive fluids often required in fluid recipe processes. The programmable relays on the Arkon MAGX2 magflows can be set to trigger (open/close) at predetermined volume measurements. So as the process starts, the flowmeter’s counter will monitor the amount of liquid passing through the pipeline and once the programmed value is reached, the relays will change state. These relays can be used to control many different types of peripheral apparatus. In the most instances, they would be used to open and close a solenoid valve to start or stop a pump [Note: magflows are generally more suited to long cycle batching processes]. They could also be used to trigger audible or visual indicators for a local display viewed by machine operators. In larger plants, where more complex automation and PID control is available to plant managers, relays or analogue 4-20 mA outputs would be wired into the PLC for system for monitoring and control purposes.
By investing in a modular magflow solution, a smaller plant can purchase and install basic instruments capable of entry level process automation with the option to upgrade as the requirements evolve. Starting with a magflow complete with programmable relays only, will be more than adequate for localised/isolated automation such as valve and pump control. Later upgrade by adding a 4-20 mA output will then enable a magflow reading to be continuously monitored and its relays controlled by a PLC and scada system. Finally, replacing the 4-20 mA output with an EtherNet TCP/IP communication module will allow for the same monitoring and control functionality, with the added benefit of a universal communication protocol and less wiring overhead as TCP/IP can be transmitted within a plant using Wi-Fi.
The Arkon MagX2
The design of the Arkon MagX2 is based on simplicity. The basic functionality is driven by a motherboard and power supply with an integral programming keypad and a local backlit display. The options are then added to suit the particular process application requirements. A miniature ‘plug-and-play’ module is fitted to the motherboard for each additional function. For example, output options include 4-20 mA, dosing connection and frequency and pulse with four programmable relays. Communication modules include Bluetooth, RS-232, RS-485, USB, GPRS or Ethernet TCP/IP. The unit is supplied standard with a MicroSD card and real-time clock for data-logging and the meters are available with universal power supplies and choice of lining and electrode materials to suit most applications.
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