GRAFCET — CIP sequence, 10 000 L fermenter
The five-step clean-in-place cycle as an IEC 60848 sequential function chart: pre-rinse to drain, 2% caustic at 80 degC, intermediate rinse to conductivity, an alternative divergence that runs the acid step only every fifth cycle, final WFI rinse to 1.3 uS/cm and 500 ppb TOC, drain and air blow, with every receptivity written as a real instrument condition for the automation engineer writing or validating the CIP phase logic.
Make it your own.
title "CIP circuit — 10 000 L fermenter, five-step clean"
step 1 "Idle — skid drained" initial
N "CIP skid isolated, V101/V102 closed"
N "Route verified against recipe CIP-05"
step 2 "Pre-rinse to drain"
N "Supply pump P201 at 12 m3/h"
N "Return valve V102 to drain"
L 300s "Pre-rinse timer"
R "Clear CIP_Complete"
step 3 "Caustic recirculation"
N "Dose NaOH to 2.0% w/w"
N "Heat return to 80 degC"
N "Recirculate, return line 1.5 m/s"
L 1200s "Caustic contact timer"
step 4 "Intermediate rinse"
N "WFI feed, return to drain"
N "Watch return conductivity"
step 5 "Acid recirculation"
N "Dose HNO3 to 1.0% w/w"
N "Heat return to 60 degC"
L 600s "Acid contact timer"
step 6 "Final rinse"
N "WFI feed at 12 m3/h"
N "Sample return for TOC"
step 7 "Drain and air blow"
N "Open drain V103"
N "Compressed air purge 90 s"
step 8 "Release to production"
S "Set CIP_Complete"
N "Print cycle report, sign off"
transition t1 : "cip_request . vessel_empty . route_verified"
transition t2 : "prerinse_timer.Q . return_turbidity < 50 NTU"
transition t3 : "caustic_timer.Q . return_temp >= 78 degC"
transition t4a : "return_cond < 20 uS/cm . cycles_since_acid >= 5"
transition t4b : "return_cond < 20 uS/cm . /(cycles_since_acid >= 5)"
transition t5 : "acid_timer.Q . return_temp >= 58 degC"
transition t6 : "return_cond <= 1.3 uS/cm . TOC <= 500 ppb"
transition t7 : "drain_level_low . air_purge_done"
transition t8 : "report_signed . qa_release"
1 -> t1 -> 2 -> t2 -> 3 -> t3 -> 4
4 -> t4a, t4b
t4a -> 5 -> t5
t5, t4b -> 6
6 -> t6 -> 7 -> t7 -> 8
8 -> t8 -> 1