Controlling Hygienic Tank Cleaning

Friday, September 22nd, 2017

How can we maintain the highest standards of hygiene in the factory? By Orsolya Sørensen, product portfolio manager, tank instrumentation, covers & accessories, and Kim Kjellberg, portfolio manager, tank cleaning, Alfa Laval

Tank cleaning is a time-honoured tradition essential for producing high quality foodstuffs and beverages. Technological advances in tank cleaning have raised the standards for food and beverage processing dramatically; the most drastic changes have occurred within the last 50 years.

On top of meeting equipment quality requirements of the European Hygienic Engineering & Design Group (EHEDG), proper control of the tank cleaning process is the primary way to differentiate equipment based upon the level of cleaning efficiency achieved. Ideally, results should be consistently accurate, reliable and repeatable.

It is important to understand the process of tank cleaning, the various tank cleaning methods and the product contained in the tank before determining the best method of control to achieve optimal cleaning efficiency.

Traditional Tank Cleaning


There are various parameters that contribute to effective tank cleaning. These are perhaps best described by the “Sinner Circle”, developed by chemical engineer Herbert Sinner to illustrate how to obtain good cleaning results via four parameters: time, action (or flow of cleaning fluid), chemistry and temperature—or TACT for short. All four are important to secure optimal cleaning efficiency; however, how they are combined is decisive in achieving optimal cleaning efficiency.

One of the oldest methods of tank cleaning, the “fill, boil and dump” approach is still used by many industries for various applications. This simple cleaning method involves filling the tank with water and chemicals and heating its contents to the required temperature. This is a very expensive and time consuming cleaning method, and the amount of force applied is minimal.

Tank Cleaning


Tank cleaning-in-place (tank CIP) is a commonly used cleaning method, which applies force to the tank surface for the removal of soil without having to open and enter the tank. There are three different types of technologies used for cleaning the tank interior: static spray ball, rotary spray head, and rotary jet head, which depending on needs, display different degrees of efficiency.

Reducing Cleaning Time By 70 Percent And Fluids Consumption By 90 Percent Recent studies indicate how the impact force from a rotary jet head is distributed in the impact area on the tank wall: the highest impact force occurs at the centre of the impact area, which decreases by approximately 50 percent 40 mm from the centre of the impact area.

It is also important to note that the rotary jet head effectively cleans high-viscosity products (e.g. sticky foodstuffs) using water at ambient temperature in just 15 seconds after the jets hit the tank wall.

In many applications, using a rotary jet head can reduce cleaning time by 50–70 percent, and cut water and cleaning fluid consumption by up to 90 percent compared to using the conventional fill-boil-dump method or static spray ball technology.

Controlling The Tank Cleaning Process

Because uptime is key to production efficiency, optimising tank cleaning performance is critical. Even automated tank CIP systems still require monitoring and control. Temperature, flow rate and chemical concentration are among the critical tank cleaning process control parameters. The performance of the CIP system itself too also requires monitoring and control to ensure that it operates according to design parameters.

Real-Time Tank Cleaning Process Control


Process control depends on reliable real-time in-line measurements using electronic sensors, such as the Rotacheck sensor, to monitor and verify the performance of a rotary jet head and tank CIP. Such devices are already readily available today. However, it is important to consider the response time of the device as well as its ability to register the actual pressure at which the jets hit the tank surface.

Fast response time (less than 25 ms) is critical to measure the impact force of the water jets accurately and reliably. Any longer a response time would provide inaccurate measurements: sensors cannot measure the entire actual impact and result in inaccurate validation of jet effect; and the signal would remain “high” on the sensor even after the jet is no longer hitting the sensor.

Registering the actual pressure at which the jet hits the tank surface is equally important. This pressure is directly proportional to the impact force; as the pressure decreases so too does cleaning efficiency, which consequently increases cleaning time.

Selecting The Right Cip Process Control System

Choosing the right system to monitor and control tank CIP processes can be challenging. It is important to define your objectives for monitoring and control and to understand the available options and advantages.

Basic sensors transmit a simple logic signal to the plant’s surface readout system or control system, which indicates all jet hits and verifies the operation of the rotary jet head. Some sensors also provide a clear visual light signal that is visible to operators on the plant floor.

Advanced sensors, such as the Rotacheck+ version, offer the same as basic sensors but include built-in intelligence. For example, the sensor can record and store the unique and actual cleaning pattern for any individual tank cleaning machine based upon its initial cleaning cycle, which has the design parameters (set point) intact.

Every time a CIP process is initiated thereafter, the sensor will compare the actual measurements to the recorded pattern (set point). Operators are immediately alerted if there is any deviation from the initially recorded time, pressure or registration of jet hits. This enables operators to immediately remedy a situation, thus reducing loss of production time. With the right CIP sensor in place, the process is under control.

Tank Cip Process Control Optimises Plant Hygiene And Efficiency

To achieve optimal cleaning efficiency for your tanks, first you must determine the right tank cleaning method for your process. Step one would include defining the cleaning criteria, understanding the options available and considering the level of cleaning efficiency and process control required.

Selecting the right tank cleaning method puts you in control of the tank cleaning process and ensures that the best cleaning results can be achieved in terms of accuracy, reliability and repeatability.

Whilst manual tank cleaning may seem sufficient for some processes, automated systems provide advantages: cleaning consistency, reduced labour costs and increased production time. Enhancing these processes also help minimise downtime, improve energy savings and reduce water and cleaning fluid consumption.

With so much invested in hygienic food and beverage production, the additional expense of hygienic sensors to validate the tank cleaning process seems a small price to pay to ensure the optimal cleaning efficiency.