Plant hygiene and sanitation (CIP)
What this domain tests
This section tests cleaning-in-place (CIP) sequence, chemistry, contact conditions and verification. The exam expects you to link soil type to detergent choice and to know why each CIP stage exists.
Core rules
- CIP relies on TACT: time, action (flow/turbulence), concentration and temperature.
- Typical sequence: pre-rinse, alkaline wash, intermediate rinse, acid wash, final rinse, sanitizer, drain.
- Hot alkali removes fat and protein; acid removes mineral scale and milkstone.
- Final rinse water quality matters; a sanitizer reduces surface organisms but does not replace cleaning.
- Verify with visual inspection, ATP swabs, conductivity/pH checks and microbial swabs.
Worked example
A 2000 L CIP caustic solution is required at 1.5% w/v NaOH. NaOH needed = 2000 × 0.015 = 30 kg pure NaOH. If the concentrate is 50% w/w lye, concentrate = 30/0.50 = 60 kg. The reasoning is a mass balance on active alkali; water is added to the final volume.
Traps
Never mix acid and hypochlorite: chlorine gas can be released. More chemical is not better; too-high concentration can damage gaskets and leave residues. CIP does not clean dismantled parts, gaskets or dead legs automatically. A clear final rinse does not prove microbiological cleanliness.