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Mission 54 · Pro PLC programming exercise

Clean, recover, rinse

Run a CIP recipe with hold and resume, routing every litre by conductivity.

Run the five-step cleaning recipe, keeping each step's time through a Hold, counting the caustic wash only while it is hot, and routing the return to drain or back to the caustic tank by conductivity.

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The 3D clean in place system this mission runs on Pro mission
Test replay

The whole recipe

Test 1 of 4
Set by the testChecked by the testStep 15 of 15 · 76.5 s
Level
Advanced
Time
About 60 min
Reward
+750 XP
Rig
3D clean in place system
Siemens editors
SCL, LAD
Rockwell editors
Structured Text, Ladder
Course stage
29. Machine lab 4: safety sequences and plant control
Automatic tests

What the tests check

  1. Each step uses the right valves.
  2. Return goes to drain or the caustic tank by conductivity, not by time.
  3. The wash only counts time at 70 °C or above, with steam control at 75 / 78 °C.
  4. Hold keeps the step and its time; resuming carries on.
  5. No flow raises Alarm and holds until Reset.
  1. Try it Use the buttons below the model and watch the rig respond.
  2. Test solution Every check runs on your code in one press.
  3. Replay If one fails, step through it one scan at a time to see why.
Why it matters

Where you’d see this on site

CIP sets clean dairies and breweries every day. Recipes like this one are the most common thing an automation engineer edits on a food site.

Sending caustic to drain costs money and harms the effluent plant; sending water into the caustic tank dilutes it until it stops cleaning. A rinse that ends on time instead of conductivity can leave caustic in food.

Where you'd find thisClean the plant without opening it, and without wasting the caustic

Dairies, breweries and drinks plants clean tanks and pipes in place, with a recipe of rinses and hot detergent. The return is sent to drain or back to the detergent tank depending on what a conductivity probe says is in it.

  1. Pre-rinseWater to drain
  2. Caustic75 °C, 30 sYou are here
  3. Push-outRecover caustic
  4. RinseUntil clean water
On a real site: places, parts and safety
  • Dairies and cheese plants
  • Breweries and soft-drink plants
  • Pharmaceutical and personal care plants

Caustic at 75 °C causes severe burns: CIP circuits are interlocked so a pipe cannot be opened while it is being cleaned.

A recipe that skips the final rinse leaves caustic in food plant. That is why the rinse ends on a conductivity reading, not just a time.

The sizes, timings and cutaways are teaching choices, not a drawing of any one real installation.

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