What is FISL?
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It says “flow ind switch low”. What I want to ask is: is this switch a switch or an alarm device? Is it just an ordinary gauge? It seems there isn’t any visible switch; if it’s an alarm, does the instrument at the site give an alarm signal, or is the alarm only sent to the control room? I’m not quite sure. Could someone please explain this? Thank you!
Did the OP post all the comments? Literally, “low ind switch low” means the flow rate indicator light switch is in the low position
Let me ask again: if it’s FISL, what signal is sent from the on-site flow meter back to the control room? Of course, there is a 4-20mA analog signal. What I’m asking is: when the flow rate is too low, since it’s an SL system, there should surely be a digital alarm signal. Does this mean that the flow meter needs to send another 0-1 signal to the ESD or DCS? It seems redundant to send a 0-1 signal to the DCS, as the DCS can presumably generate the alarm signal on its own based on the 4-20mA signal and the set alarm values during configuration I’m not quite sure. If it is the flow meter itself that sends 0-1 low-level alarm signals to the control room, then does it mean that the alarm values need to be set manually on-site during installation? Can the flow meter meet this requirement? Hehe, I don’t quite understand; it’s just a wild guess. I have no idea what’s going on actually
The flow meter sends signals back to the control room; these can be 4-20 milliamps or pulse signals, with the flow rate being determined based on the frequency. When the flow rate is low, it can be adjusted via the analog settings on the DCS, or a relay can be activated to send an analog signal. In order to use ESD, the analog signal must be acquired prior to reaching the DCS (by using a flow control module): handshake