CIP Clean in Place: Process and Benefits

CIP system is the abbreviation of Clean In Place, in-situ cleaning (in-line cleaning, in-place cleaning).

System introduction

CIP cleaning is CLEAN IN PLACE (in-situ cleaning).

CIP cleaning is a safe and automatic cleaning system that can be operated simply and does not dismantle production equipment.

CIP cleaning technology has been widely used in the advanced food industry; for example, the yeast industry's leading company, Angie's yeast, uses a complete set of CIP cleaning procedures for pipe and tank cleaning.

CIP cleaning device has the following advantages.

1. It can rationalize production planning and increase production capacity.

2. compared with hand washing, the cleaning effect is not only affected by the difference of operators but also the product quality can be improved.

3. It can prevent the danger in cleaning operations and save labor. 

4. It can save cleaning agents, steam, water, and production cost. 

5. It can increase the service life of machine parts.


Mechanism of action

The chemical energy is mainly generated by the chemical reagents added to it, which is the most critical factor in determining the washing effect. General manufacturers can choose detergents according to the nature and degree of pollution of the cleaning object, the composition of the material, water quality, the selected cleaning method, cost, and safety. Commonly used detergents are acid, alkali detergent, and sterilization detergent.

The advantages of acid and alkali detergents are that: they can kill all microorganisms; remove organic matter better. Disadvantages include intense irritation to the skin; poor washability.

The advantages of sterilizing agents are: sterilization effect is rapid, practical for all microorganisms; generally non-toxic after dilution; not affected by water hardness; form a film on the surface of the equipment; concentration is easy to determine; easy to measure; can remove foul odor. Disadvantages are a unique smell; requires certain storage conditions; different concentrations of sterilization effect are very different; low temperatures are easy to freeze; improper use will produce side effects; mixed with dirt sterilization effect is significantly reduced; spilled easily pollute the environment and leave traces.

Acid and alkali detergents in the acid refer to 1%-2% nitric acid solution, and alkali refers to 1%-3% sodium hydroxide at 65 ℃ -80 ℃ use. Sterilizing agent for the often used chlorine bactericides, such as sodium hypochlorite, etc.

Thermal energy in a specific flow rate, the higher the temperature, the smaller the viscosity coefficient, and the greater the Reynolds number (Re). The temperature rise can usually change the physical state of dirt, and accelerate the speed of chemical reactions while increasing the solubility of the earth, to facilitate the cleaning of impurities solution, thereby improving the cleaning effect and shortening the cleaning time.

Re measures the size of the movement energy. The general standard of Re is the thin liquid flowing down from the wall, tank type Re>200, tube type Re>3000, while Re>30000 effect is best.

The solubility of water: water is a polar compound; almost no solubility of greasy dirt, carbohydrates, proteins, or low fatty acids have a specific solubility, and the dissolution of electrolytes and organic or inorganic salts is more substantial.

Mechanical action by the action of movement, such as stirring, spray cleaning fluid generated by the pressure and friction, etc.

Influencing factors

Equipment pollution degree, the nature of pollutants and product production process, etc. It is an important reason to determine the cleaning effect; if the cleaning is not based on its characteristics to assess the conditions of CIP, it is difficult to achieve the desired purpose and leads to high cleaning costs and other defects.

Types of detergents Currently, many kinds of detergents are used in the food industry, mainly acid and alkali, etc., of which sodium hydroxide and nitric acid are the most widely used. Alkali detergents have a good removal effect on dirt containing high protein but have a specific corrosive impact on food, rubber gaskets, etc.

Acid detergents have an excellent effect on the stubborn dirt that alkaline detergents can not remove. Still, if there is a certain degree of corrosion on the metal, some anti-corrosion agents should be added or rinsed clean with water. Detergents and surfactants, chelating agents, etc., but only in special needs, such as cleaning water hardness is high when you can use chelating agents to remove metal ions.

Cleaning agent concentration: when the cleaning agent concentration is increased, the cleaning time can be appropriately shortened to compensate for the lack of cleaning temperature. The increase in cleaning agent concentration will cause an increase in cleaning cost, and the rise in concentration is not necessarily effective in improving the cleaning effect, so manufacturers must determine the appropriate concentration according to the actual situation.

Washing liquid temperature: Generally speaking, the chemical reaction speed will be increased 1.5-2.0 times for every 10℃ increase in temperature, and the cleaning speed will be increased accordingly, and the cleaning effect will be better. The cleaning temperature is generally not less than 60℃.

Cleaning time is affected by many factors, such as cleaning agent type, concentration, washing temperature, product characteristics, production pipeline layout, equipment design, etc. Cleaning time must be appropriate; too short can not effectively remove dirt, and too long is a waste of resources.

Take the beverage industry as an example; its cleaning procedure is as follows.

1. washing 3-5 minutes, hot water at room temperature or above 60℃; alkali washing 10-20 minutes, 1%-2% solution, 60℃-80℃; intermediate washing 5-10 minutes, clear water below 60℃; final washing 3-5 minutes, clear water.

2. washing 3-5 minutes, room temperature or hot water above 60℃; alkali washing 5-10 minutes, 1%-2% solution, 60℃-80℃, intermediate washing 5-10 minutes, clear water below 60℃, sterilization 10-20 minutes, hot water above 90℃.

Washing flow to ensure the flow rate is actually to ensure the cleaning fluid flow rate when cleaning to produce a specific mechanical effect, that is, by improving the turbulence of the fluid to improve the impact and achieve a particular product of cleaning.

Judging criteria

The cleaning effect must meet the following criteria as an ideal CIP for the food industry.


●Odor: Fresh, with no strange odor, for a unique treatment process or particular stage allows a slight odor but does not affect the safety of the final product and its quality.

●Visual: Bright cleaning surface, no water accumulation, no film, no dirt or other. At the same time, after CIP treatment, the production processing capacity of the equipment is changed.

Hygiene Index: Microbiological index reaches the relevant requirements; it cannot cause the improvement of another hygiene index of the product.

Economy: Considering that cleaning can be satisfied simultaneously, the cost is an essential factor in measuring the cleaning effect.

Operation CIP operation must be relatively safe, convenient, etc.

According to different classifications, the CIP device has other components, but in general, it consists of tanks (barrels), pipelines, heaters, pumps, control cabinets, and accompanying equipment. The whole device is usually made of stainless steel 1Cr18Ni9 (SUS302), 0Cr19Ni9 (SUS304), 0Cr17Ni12Mo2 (SUS316), and 1Cr18Ni9Ti. The tank is used to store the cleaning liquid; the inner wall must be polished, the inner surface Ra ≤ 1.0μm; the outer surface Ra ≤ 2.5μm can be processed according to the need; the upper and lower heads are disc-shaped and oval, and the bottom seal can also be used conical, the cone angle can refer to the rest angle design to facilitate cleaning; the pipeline can be divided into inlet pipeline, discharge pipeline, heating cycle cleaning pipeline, self-cleaning pipeline, etc., the pipeline control valves, online detectors, filters, cleaning heads and other configurations are equipped according to the design requirements.

The heater often uses a plate heat exchanger, serpentine coil form of indirect heating, and silent direct steam heating. The advantages of the plate heat exchanger are known for its high heat transfer coefficient, occupying a small space, but relatively high price, and easy to block; coil heat exchanger has the advantage of simple structure, low price, but to be placed in the tank, easy to scale, the surface to be cleaned manually; silent heater structure is simple, low cost, high thermal efficiency, but easy to change the concentration of the tank liquid, and easy to scale; pump is often used centrifugal ram type, the giant pump of this kind characteristic is that the overflow parts are polished, no dead ends, easy to clean, so commonly known as a sanitary pump.

Automatic control and cleaning process

CIP system control has two ways: manual control and automatic control.

Manual control is entirely by hand to operate the valve, such as adding liquid, cleaning, discharge, temperature control, and other functions. The designer requires automatic control to set the flow, temperature, concentration, pressure, time, and other parameters that can be adjusted instruments and meters for automatic control of the CIP system, and according to the set cleaning process, with the least amount of time, workload, consumption, to complete the purpose of cleaning and achieve maximum profit. Since considering acid, alkali, and other cleaning solutions to human injury and cleaning quality is an essential factor in aseptic production, the automatic control of CIP is necessary.

Many people may think that the CIP device is to use water and alkaline water to rinse against the inner cavity of cleaning equipment. The CIP device should be designed according to its cleaning process.

First, it should be clear what is the object of cleaning, what cleaning agent is needed to clean it, and the number of cleaning agent species to determine the number of tank washing.

The second is to determine the concentration of the cleaning agent (including water), temperature, pressure, speed, time, distance (from the cleaning tank), and Reynolds number.

The third is the order of cleaning, what to wash first, what to clean after, and which one-time wash is regularly washed. These are the basis for the development of the cleaning process and the basis for selecting the configuration. The key to the CIP system is its cleaning process. Equipment is the hardware; the process is the software. Different cleaning objects (beer, drinks, juice, dairy products, pharmaceutical solutions, mineral water, food, cosmetics, etc.), in essence, should be different cleaning processes. Research CIP should be the study of the cleaning process.

So far has not been developed for a complete, scientific, systematic, standardized cleaning process for beer, beverages, dairy products, and other industries. The manufacturers who provide equipment often do not have the conditions for such research. To overcome the blindness of the design, only the equipment designer, cleaning agent suppliers, and customers are in close contact, joint analysis, and research to make more ideal to meet customer requirements of CIP equipment. Now only provide a four-tank CIP cleaning process program for reference only.

Cleaning agent Description Temperature (℃) Concentration Time (min)

(before the shift)

Aseptic water ClO2 pressure washing RT 2ppm 5

Alkaline water NaOH 50 0.5-3% 20

Hot water 80 5

Hot water Disinfection 85 30

Hot water 50 20

(After shift)

Sterile water ClO2 disinfection wash RT 2ppm 5

Alkaline water NaOH 50 0.5-3% 20

Hot water 80 5

Hot water Disinfection 85 30

Hot water 50 20

Sterile water ClO2 seal wash RT 2ppm 5-10


Acid washing HNO3 descaling RT 1-3% 10-15

Clean water ClO2 disinfection wash RT 2ppm 15-20

The process cleaning agent in the pipeline pressure P = 0.2MPa for the cleaning time is the most ideal and is still open to discussion.

The CIP device plays only a supporting role in the whole canning line, although it is essential. So it is easy to be overlooked. Once new standards are enacted and enforced in food and beverage production, they will also undoubtedly improve CIP equipment's design and function requirements. Suppose the basic configuration of the equipment is established from now on. In that case, it will be able to adapt as soon as possible to the more stringent legal requirements proposed by future legislators.

Tank washing device

The CIP unit is designed to clean the closed containers in the canning line, while the can washing unit is designed to clean the inside of the cans in the CIP unit. It tends the cleanliness of the CIP device directly affects the cleaning effect of the cleaning object, so it should be paid attention to when the near future HACCP or GMP standards in the food, beverage, and dairy production industry, the implementation the time, will have to CIP equipment for the technical determination of cleaning effectiveness.