Lesson 3 - Cleaning Systems and Control SAQ

**Describe the factors affecting cleaning efficiency and how they influence each other.

Response:

The four factors affecting cleaning efficiency are described from the ‘Sinner Circle’;

• Mechanical action refers to the physical removal of soil through pressure or frictional forces generated by turbulent flow. The greater the mechanical action applied, the more effective and quicker the cleaning becomes. In modern brewing cleaning systems, mechanical action has been incorporated into higher pressure systems such as rotary jet cleaning.
• Chemical type, formulation and concentration each have a role to play. Detergent formulations are made more effective through the addition of compounds that increase wettability and sequestering power (or ability to bind metal ions that can cause scale). Additives make the base cleaning agent more expensive; however, these may be crucial; for example, if the water used for cleaning contains temporary or permanent hardness, which can form scale on surfaces.
• Temperature increases the cleaning effectiveness (up to an optimum temperature) and depending on the detergent used. However, detergent formulations may become unstable at high temperatures. This can cause the precipitation of dissolved soil substances. With nitric acid based detergents, it can cause a breakdown of the active ingredient, reducing the effectiveness. Increased temperature means increased energy use, something that needs to be optimised in the modern brewery.
• Time is at a premium in the brewing process, and often cleaning duration is limited in order to turn equipment around quickly. This requires shortened cleaning cycles, perhaps using only a hot water sterilisation step. An example of this is with filtration and packaging fillers where a full cleaning cycle is performed during planned stoppage times.

Each of these four factors can compensate for each other. One of the key objectives in CIP is to balance cleaning time with production scheduling needs.

Temperature may be increased to a limit, with increasing temperature improving the cleaning efficiency. However, in cold CIP environments, this opportunity may be limited. In this case, we need to consider chemical and mechanical factors.

Chemical or detergent strength may also be increased to a point where the plant components may be at risk of damage. Using a different chemical make-up may also compensate for a reduced time.

Mechanical cleaning refinements offer a big opportunity for improving cleaning. This begins by looking at the plant design and removing hard to clean shadow areas and dead legs. At the same time, the brewer can look at the flow rate in pipes to ensure there is a turbulent rather than laminar flow, to allow for cleaning effectiveness.

In vessels, the pressure on the spray head needs to match the installed specifications. If the pressure is too high, the possibility of misting exists. If it is too low, there may be insufficient pressure to jet the detergent to the tank wall. High pressure devices are designed for increased pressure and remove soil by mechanical action. The use of burst rinsing can also increase the chemical cleaning required by allowing the detergent to penetrate and loosen the soil.