P&ID representation

Dear,

I trying to proper represent a P&ID logic by showing a selector switch that switches between relay and PLC mode as indicated.

please advise if it is correct or it needs to be adjusted.

Any comment is really appreciated,

Charbel

where your legend

I am following related ISA standard

the symbol for the pump positive or centrifugal pump?
where the pump inlet?

I means what?

- I would prefer to point HS-xxxx to the selector symbol and delete both rigth/left lines.
- I'm not sure about HSI-xxxx. I found people used HI or HL in other diagrams.
- That tree of selectors under the relays control is a little confusing. I'd not know how to identify them on the field using your diagram.

Charbel said:

I trying to proper represent a P&ID logic by showing a selector switch that switches between relay and PLC mode as indicated.

Click to expand...

This is totally proper if designed this way. If you are allowing for two control modes, one purely as hardwired level transmitters or switches wired directly to the pump controls versus the PLC handling the level control. The HS would allow an operator to switch between the two modes.

However, it's a little hard to see some of the symbols on your expanded view to determine what you're trying to do.

Maybe give us more explanation of you system.

just guess,