Regarding remote control adjustment
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In a recent project, one of the requirements specified for the process was remote control of the adjustment mechanism; the medium involved was steam and circulating water, and it was necessary to be able to remotely control the opening degree of the control valve, denoted by the acronym HIC. I have just entered this industry and this is my first time dealing with remote control adjustment. I would appreciate it if experts could advise me on how to choose the right product and what aspects need to be taken into consideration. Thank you.
To obtain a valve whose opening degree can be adjusted, manual valves are generally replaced with diaphragm-type control valves (there are many manufacturers to choose from). If the steam temperature is high, it is advisable to use a high-temperature version; a control signal of 4–20mA is sent out by the control module (PLC/DCS) to adjust the valve’s opening degree.
When selecting a valve, calculate the CV or KV value based on the process conditions (the formulas are usually provided in the samples); choose the appropriate CV or KV value considering the valve’s diameter and the size of its core. Then, use the selected CV or KV value to determine the opening degree of the control valve (an opening degree of 20%–80% is ideal, with around 70% being the best choice). Pay attention to the material of the valve as well.
HIC stands for manual control loop, also known as remote control; it involves manually adjusting the opening degree of the on-site control valve using a controller in the control room. The controller can be a separate instrument or it can be provided by the manual module of the DCS.
This is relatively simple – just use a manual controller to adjust the valve. For selection, you need to refer to the selection manual based on the conditions at your site