What do these DCS symbols mean?
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I know that HS in the diagram refers to a manual valve, but what do HS± and *+A- mean? Seeking help from everyone
Why is everything DCS? Is this really DCS?
I’m not entirely sure, but it seems that power supply and control functions are located on the sides; there is a change in diameter at both ends. Without any diagrams for reference, I guess it’s an electric valve.
It should be an electric valve, used to open or close
M – refers to the motor (although it could also be other motorized equipment); I assume it is an electric rotary valve that requires forward and reverse operation, with + indicating forward motion and – indicating reverse motion (the same applies to the status as well)
HS is not a manual valve, but a manual switch. It relates to the operation of the pump motor; the HS at the top is the operation switch installed on-site, while the HS at the bottom is the operation switch on the DCS. As for the meaning of the suffix symbols (i.e., the functions they represent), it is necessary to refer to the design documents. Motor operation mainly involves starting and stopping, forward and reverse rotation, operating status, current display, and so on.
This answer is quite accurate. My understanding is that the element at the very top of the icon represents the control functions (manual on/off control), while those below it represent the instrument functions – that is, functions related to the motor such as forward/reverse operation, current display, and operating status. Each item will have an alphabet.
Guess: local switch for the pump, DCS-side switch, operation signal.
The first is manual operation on-site; it can be used to switch in 2 directions or to increase or decrease the load. The second is the DCS manual operation, which only allows for shutting down or reducing the load. The third one is a bit difficult to distinguish; in my opinion, once this circuit is set to automatic mode by the DCS, when a certain deviation or some parameter increases, the DCS can automatically shut it down or reduce the load. It is also better to understand it in light of one’s own actual process conditions.
HS manually controlled switch, HS+, remote start； HS – Remote shutdown; *+A- should indicate information related to position (displacement/vibration). These are abbreviations used in PID control systems, and the terminology may vary slightly depending on the specific process design. For detailed information, refer to the PID legend provided by your plant’s design agency, which contains thorough explanations including details on pipeline materials/pressure ratings, valve types, control logic configurations, and even basic design information for the equipment. Based on these PID diagrams, it is easy to understand how the process operations should be carried out in the future. Of course, understanding this information requires a certain level of knowledge in process engineering and instrumentation