CIP vs OPC cleaning: what is the difference and when to use each

15 Oct 2026 · 6 min read

Every food, dairy and beverage plant has two very different cleaning jobs. One is the inside of closed equipment: pipelines, tanks, heat exchangers and fillers that product flows through. The other is everything that is open to the room: conveyors, tables, floors, walls, drains and the outside of machines. Clean-in-place (CIP) and open plant cleaning (OPC) are the two methods designed for these jobs.

A third method, clean-out-of-place (COP), sits between them. Parts are removed from a machine and washed in a tank or parts washer. Understanding where each method fits helps you choose the right chemistry, the right equipment and the right safety controls, and avoids the common mistake of using one product for every surface.

This guide explains each method, the typical sequence of steps, the chemistry usually involved and a practical way to decide which approach a piece of equipment needs.

What clean-in-place (CIP) means

CIP cleans the internal surfaces of closed equipment without taking it apart. Cleaning solutions are pumped through the same lines and vessels the product uses, often from a dedicated CIP set with tanks, a pump, a heater and return lines. Spray balls or spray devices distribute solution inside tanks.

Because the solution is recirculated under turbulent flow, the cleaning action comes from chemistry, temperature, time and flow velocity rather than scrubbing. Foam is a problem in a recirculating system: it causes pump cavitation, poor contact and overflowing tanks. CIP detergents therefore need to be low-foaming.

1. Pre-rinse with water to push out loose product and soil.

2. Circulate an alkaline detergent to remove fats, proteins and milk residues.

3. Intermediate rinse to remove detergent and loosened soil.

4. Where mineral deposits or milkstone build up, circulate an acid step, then rinse again.

5. Sanitise the cleaned surfaces with a suitable sanitiser, following the label for rinse requirements.

6. Verify: check rinse water, inspect where possible and record the cycle.

• Clastox 50High Performance Alkaline DetergentPotent alkaline liquid detergent specially engineered for heavy-duty cleaning. Provides exceptional scale prevention and hard water resistance while effectively penetrating into stubborn soils, animal fats, and milk residues.
• Clastox PlusLow Foaming Heavy Duty Alkaline DetergentPotent alkaline liquid detergent specially engineered to meet the rigorous demands of food processing plants. Its advanced detergent systems not only penetrate deeply into stubborn soils, animal fats, and milk residues, but also provide exceptional scale prevention and hard water resistance, ensuring that your cleaning operation runs smoothly and efficiently. Designed for heavy-duty applications.
• Sanix PeraxyPeracetic Acid Based SanitizerClear liquid oxidizing sanitizer for the food industry, formulated with peracetic acid, hydrogen peroxide, and acetic acid. Eliminates a broad spectrum of microorganisms, including bacteria, spores, and viruses, ensuring high-level sanitation for pre-cleaned surfaces.

What open plant cleaning (OPC) means

OPC covers every surface that can be reached by hand or by a hose: conveyor belts, cutting tables, hoppers, floors, walls and the exterior of machines. Here the challenge is contact time on vertical and complex surfaces, so foam is useful rather than harmful. A foaming detergent applied with a foam lance or foam unit clings to surfaces, shows the operator where product has been applied and keeps the chemistry working on the soil.

1. Dry clean: remove product scraps and debris by hand or with scrapers.

2. Pre-rinse with low-pressure water from top to bottom.

3. Apply foam detergent evenly, working from the bottom up so coverage is visible.

4. Allow the foam to work, then agitate heavily soiled areas with brushes or pads.

5. Rinse thoroughly from the top down so dirty water runs to the drain.

6. Apply sanitiser to food-contact surfaces after cleaning, as directed on the label.

• Alkalox FoamHigh Foaming Alkaline DetergentHigh-foaming alkaline detergent engineered with advanced surfactant blends to create a high foam that clings to surfaces. Ideal for use in the food industry, including dairies, meat processing plants, and preserved food facilities. Tackles tough, industry-specific soils.
• Acidox FoamHigh Foaming Acidic DetergentPowerful, high-foaming acidic detergent specifically formulated to meet the stringent cleaning requirements of the food and beverage industry. Effectively removes scales, particulate matter, and inorganic soils.
• Chlorox FoamChlorinated Alkaline CleanerChlorinated alkaline cleaner with high chlorine concentration, ideal for daily cleaning in the food industry. Its exceptional foaming ability effectively removes various soils in food processing, meat, dairy, and vegetable processing. Functions as a 2-in-1 cleaner and sanitizer.

Where clean-out-of-place (COP) fits

Some equipment is too intricate for CIP but too small or delicate for open foam cleaning: filler valves, gaskets, pump impellers, nozzles, moulds and small utensils. These are dismantled and washed in a COP tank, a soak bath or an agitated parts washer. A low-foam alkaline detergent is usually the right base, because COP tanks recirculate or agitate the solution. Parts are rinsed, sanitised and reassembled with clean hands and tools.

Chemistry choices for each method

• CIP: low-foam alkaline detergents for organic soil; an acid step for mineral scale. Evochem does not list a dedicated acid CIP detergent, so ask our technical team for the right option for your circuit.

• OPC: high-foaming alkaline detergents for fat and protein, high-foaming acidic detergents for scale and inorganic soil, and chlorinated alkaline foam where the plant’s hygiene plan calls for it.

• Neutral foam detergent for general areas and for surfaces where a strong alkali is not wanted.

• Sanitisers such as peracetic acid or quat, applied only to surfaces that have already been cleaned and rinsed.

• Always check that a product is compatible with the materials in your equipment, including soft metals, gaskets and coatings, and read the label before first use.

Safety in CIP and OPC

CIP chemicals are handled in concentrate and often at elevated temperature, so the main risks are splashes during tank make-up and accidental opening of a line during a cycle. Interlocks, lock-out procedures and correct PPE matter. In OPC, the operator is close to the spray, so goggles, gloves, aprons and boots are essential, and foam should never be applied over live electrical panels.

Never mix acid products with chlorinated products: the reaction can release chlorine gas. Keep acids and chlorinated alkalis in separate, labelled storage and rinse thoroughly between steps. Keep the MSDS for every product at the point of use.

How to decide which method to use

• If product flows through it and it cannot be opened easily, it is a CIP candidate.

• If you can see and reach the surface, it is an OPC job.

• If the part is small, intricate and removable, use COP.

• If a CIP circuit still leaves residue at dead legs or valves, add a periodic manual or COP clean for those parts.

• Match foam level to the method: low foam for CIP and COP, high foam for OPC.

Talk to our technical team

Tell us about your site, soils, equipment and volumes. We will recommend products and dilutions, and send pricing for bulk supply.