US The Short Answer
Clean in place (CIP) cleans the product-contact surfaces inside closed process equipment without dismantling it. Pumps circulate rinse water and cleaning chemicals through pipework, tanks, heat exchangers and fillers, and a controller checks that each step reached the right time, temperature, flow and concentration before the line is released back to production.
A Typical CIP Cycle
Cycles vary by plant and product, but most follow the same pattern: a pre-rinse to remove loose product, an alkaline wash (typically dilute sodium hydroxide at 70 to 80 °C) to lift fats and proteins, an intermediate rinse, an acid wash to remove mineral scale, a final rinse and a sanitizing step. Conductivity sensors confirm when one solution has been flushed out and the next has arrived.
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Clean in place (CIP) Automated cleaning of closed equipment from the inside, with no dismantling.
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Clean out of place (COP) Parts are removed and cleaned in a parts washer or tank.
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Open-plant washdown Manual foam, rinse and sanitize of the outside of machines, floors and everything in the splash zone.
Where HMIs Fit
Every CIP set is run from a PLC and an HMI that shows the cycle, records the verification data and alarms when a step fails. That HMI sits outside the closed circuit, so CIP chemicals never reach it, but it is still foamed and hosed during open-plant washdown. Our guide to hygienic design for washdown computers explains what that means for sealing and materials.