How to choose the color for the digital I/O panel of DCS
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How are the colors for the ON and OFF states of digital signals determined? It is determined by using green to represent the normal state and red to represent the abnormal state. Interlock activation/deactivation: ON/OFF, green/red. Valve fault: normal/ON/OFF, red/green. Especially in this case: if the valve head indicates the control signal, that is, whether the solenoid is powered (green) or not (red), and if the valve body receives a feedback signal – when the solenoid is powered, the valve is in a closed state (red); when the solenoid is not powered, the valve is in an open state (green) – then it’s definitely not appropriate for the entire valve to have a green color on its head and a red color on its body. How to determine this color?
It depends on the industry; the power sector is different from other chemical industries in the country. In the power industry, red generally indicates operation. But in the chemical industry, green means operation. The indication for stopping in case of a fault is not necessarily the same; it mainly depends on how the entire plant defines it, and once defined, this is communicated to the process department. You can judge the status of the process by yourself.
If the original poster thinks it’s not appropriate, they can consider drawing an electromagnetic valve next to it and marking the color of the signal output by that valve. Additionally, it is not a problem if the color output by the solenoid valve differs from the color of the feedback signal from the valve body itself; as long as all valves use the same color, process workers will be able to determine whether the valves are in the correct position by comparing the colors once they become familiar with this system. Also, during on-site construction, it is essential to ensure consistency at the site; even things like modifying pneumatic pipelines or relay wiring must be done so that when DO is set to 1, the system is required to be in either the on or off state. Try to avoid specializations, as this can create problems down the road or when someone else takes over maintenance tasks.
If the original poster thinks it’s not appropriate, they can consider drawing an electromagnetic valve next to it and marking the color of the signal output by that valve. Additionally, it is not a problem if the color output by the solenoid valve differs from the color of the feedback signal from the valve body itself; as long as all valves use the same color, process workers will be able to determine whether the valves are in the correct position by comparing the colors once they become familiar with this system. Also, during on-site construction, it is essential to ensure consistency at the site; even things like modifying pneumatic pipelines or relay wiring must be done so that when DO is set to 1, the system is required to be in either the on or off state. Try to avoid specializations, as this can create problems down the road or when someone else takes over maintenance tasks.
Draw a valve icon on the flow diagram screen and then make connections. In power plants, red indicates operation while green indicates shutdown; in the chemical industry, red indicates shutdown while green indicates operation
A small square with an “S” marked on the valve body indicates the solenoid valve, which is very intuitive. A box combined with a valve body represents a control valve. 1. The color of the valve body changes when the valve is turned on or off: green when open, and red when closed. 2. The filling color of the “S” box changes when the solenoid valve is powered or de-energized: green when powered, and red when de-energized. It’s not contradictory at all; valves are originally classified as FO and FC, which makes them easy to distinguish and is also accepted in the industry.