Draft teaching material marked until The Planner's Bench team signs off on technical accuracy. Symbols follow generally known public conventions (ISA style instrument bubbles, common mechanical and electrical one line shapes). Your site's drawing standards and procedures always govern.
Tag list
PT-1501A/B/C Pressure transmitters, voted 2 out of 3
UY-1501 Safety logic solver input / vote
UV-1501 Trip valve (final element)
How it works
Three pressure transmitters vote in the safety logic. When two of three exceed the trip point, UY-1501 de energizes UV-1501 to the safe state (closed in this example). This loop is independent of the normal PIC. Proof tests must exercise sensor, logic and final element.