What is Cleaning in Place and How Does it Work?

CIP Line & Vessel Cleaning

When cleaning lines in process equipment using CIP, the correct fluid velocity must be achieved to obtain good cleaning. Laminar flow, from velocities below 1.5m/sec does not give good cleaning characteristics. What is required is turbulent flow at velocities between 1.5-2.1 m/sec. There is no gain at velocities above 2.1 m/sec.

In the cleaning of vessels two main methods are generally employed. The first uses high pressure cleaning heads to remove soil by mechanical action: the vessel surface being contacted in a series of passes. The second method employs low pressure cleaning heads that rely purely on chemical action to remove the soiling.

CIP Return

The majority of problems with CIP can be attributed to poor CIP return. This causes excessive CIP times, excessive use of detergent and heat with high effluent discharge.

To overcome these problems the system for Return must quickly and efficiently return the cleaning solutions back to the CIP Set. Critical in this respect is the choice of scavenge pump.

Poor scavenge allows back up of cleaning solution and poor cleaning of the lower part of the vessel. In contrast, effective scavenge allows fresh cleaning solutions to contact the vessel walls and carry away soil effectively.

CIP Optimisation

Most CIP sequences are never altered from post installation settings; these are usually a set of “defaults” which are set on commissioning. However CIP operators can optimise their systems by monitoring a number of key parameters. These are:

• What temperature and concentration (conductivity) are the Caustic tanks set to? - often set too high with no added benefit.
• Consider the Pre-Rinse – does it run clear and then keep going?
• Caustic Fill – how high are the Return Conductivity and Temperature Transmitters set?
• Intermediate Rinse – is it removing caustic solution and temperature prior to sterilisation?
• Sterilisation – what strength is the sterilising agent and how long is the contact time?

Finally all changes resulting from the CIP monitoring process should be documented and validated to meet any statutory regulations, and/or specific client requirements.