Turbidity Sensors

How can turbidity sensors help optimizing processes and saving cost?

In many applications in the fluid food and beverage industries, turbidity measurement is the most suitable analysis technique for differentiating liquids in the process inline. With the hygienic turbidity meters of the ITM series, processes can be monitored with high precision and controlled in real time. With two different methods of measurement, Anderson-Negele hygienic inline turbidity sensors offer the appropriate turbidity measurement principle for every degree of turbidity: from the lowest measuring range of 0…5 NTU (0…1 EBC) for slightly turbid media to the measuring range of 200…300,000 NTU for products with medium and high turbidity. Since fat particles display the same behavior as solid particles or other turbidity substances when measuring turbidity, dairy products such as milk or cream can also be analyzed very accurately. Here are only a few examples for turbidity values of different media and their alterations in varying concentration:

ROI calculator for the turbidimeters ITM-51 / ITM-4

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Compared to time control or visual monitoring or due to shorter response times, inline analysis of turbidity can save you time and thus resources at every phase transition. In a real case our customer saves 65 seconds per phase transition compared to time control (open case study).

Our ROI calculator helps you with a rough calculation of how quickly the installation of a turbidimeter pays for itself through savings in product costs alone – just click on the links here:

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What are typical applications for hygienic inline turbidity sensors?

The inline analysis of media based on their turbidity values enables automated, high-precision application in many production processes and application areas. These are primarily product differentiation, phase separation, process control and quality monitoring.

Product differentiation by differentiating between liquids, the correct processing, storage or filling of products can be ensured, for example:

• Milk with 3.5% or with 1.5% fat content, cream with 10% or with 30% fat content, or whey
• Beer or wort or water
• Various fruit juices
• Product or water or cleaner

Phase separation: in combination with conductivity measurement, inline CIP control down to the second is possible:

• The phase separation in real time between water – caustic – acid – product ensures a verifiable, safe, efficient and resource-saving phase separation and thus cleaning quality.

Process control: if the turbidity level rises above or falls below a certain preset value, a process correction can be triggered by a signal to the process control PLC. Typical applications are:

• the filter monitoring, where the turbidity is continuously measured after a filter
• the separator control system, in which the filter residue is automatically ejected into a waste container on reaching a specified turbidity value,
• the CIP process, where an automatic decision on reuse or disposal is made in the CIP return flow by controlling the degree of pollution

Quality monitoring: Furthermore, the concentration or the turbidity level of certain products can be monitored:

• Cream, for example, can be optimized to the desired concentration
• In breweries, the turbidity level of craft beer or other unfiltered or weakly filtered beers can be kept within a certain target range for a constant product quality
• Juices and other mixed drinks can also be kept at a uniform, desired level of turbidity to guarantee customers a consistent product experience.
• Fresh water and drinking water can be analyzed before mixing with product

In which industries and applications do hygienic turbidity sensors make sense?

In a variety of production processes and in CIP systems in dairies, breweries, the beverage industry, wine production, juice production and other food companies, turbidity sensors can measure liquids according to qualitative criteria in real-time and fully automatically. This allows, among others, to:

• differentiate products and other liquids instantly and reliably and monitor them in the process (automated phase separation in real time). Result: Maximum utilization of resources
• continuously monitor processes for their function, for example by supervising filters and separators. Result: Avoidance of production downtimes or damage to equipment
• optimize the quality of products, e.g. to bring the turbidity of craft beer or the concentration of cream to the specified value in the most efficient way. Result: Higher and more precise product quality and avoidance of quality deviations
• control the cleaning media and also the rinsing water in the CIP return flow for reusability by analyzing their degree of contamination. Result: Maximum multiple use and thus saving of expensive CIP cleaners as well as reduction of water consumption and waste water volume
• monitor the filling process of products by ensuring that the correct fluid or product in its correct concentration is filled into the packaging. Result: Avoidance of incorrectly filled products
• monitor the integrity of the cooling circuit by continuously monitoring the glycol for foreign matter caused by the ingress of other media. Result: Alarm signal before a failure of the cooling circuit can occur and thus avoidance of severe damage

Which turbidity sensor fits best to your application?

Which other methods can be replaced by turbidity measurement?

In practice, the degree of turbidity is often not easy to detect, but it can be decisive for the quality of the end product and the efficiency of the process. Still frequently used methods of control are manual sampling or turbidity monitoring via a sight glass. However, experience shows that both of these methods involve high personnel costs and uncertainties in the quality between samples.

Another common option for certain applications such as CIP cleaning is the time-controlled phase change. However, a safety buffer of several seconds must be taken into account to ensure that no incorrect product or cleaning agents enter the product tanks. This results in costs for each phase change, as many liters of valuable product or cleaning agent end up in the waste water.

The Anderson-Negele turbidity meters of the ITM series can automate this process step with a very high measuring accuracy. This prevents loss of resources due to media being discharged incorrectly or too late and personnel costs due to visual or manual control, thus saving money. In many practical cases the use of an Anderson-Negele turbidity sensor has been amortized within a very short time.

Which measuring principles exist for turbidity sensors?

Basically, the Anderson-Negele turbidity meters are divided according to their measuring principle into relative turbidity sensors with backscattered light method and four-beam turbidity sensors with recording of the measured values of transmitted and scattered light. Both are inline measuring methods, i.e. they analyze the liquids in the running process. Due to the extremely fast response times of less than 1 second, the processes can be monitored and controlled in real time.

What is relative turbidity measurement?

The main advantages of this measuring principle using the backscattered light method are the flush inline installation of the sensor in the process and the favorable price. Thanks to a wide range of process adaptations, the ITM-51 can also be easily integrated into existing pipes from DN25 upwards at a later date, in compliance with internationally recognized hygiene guidelines such as 3-A and EHEDG.

From a diode at the tip of the sensor, an LED light source emits infrared light into the medium via an optical system made of highly resistant sapphire. The particles present in the medium reflect the irradiated light, which is detected by the receiving diode in the sensor tip (so-called backscattered light method). The electronics calculates the relative turbidity of the medium from the received signal. This measuring method is ideal for measuring media with medium to high turbidity (200…300.000 NTU).

What is four-beam turbidity measurement?

In the ITM-4, turbidity measurement using the transmitted light / scattered light method is carried out using the 4-beam alternating light method, also with an LED light source. The main advantage of this measuring principle is the very high measuring sensitivity. With its measuring ranges starting from 0…5 NTU (0…1 EBC) even the slightest changes in turbidity are registered and output.

Two infrared transmitters and two infrared receivers are arranged in the ring-shaped measuring sensor, each offset by 90°. The transmitters are controlled alternately to determine the turbidity value. If transmitter 1 is active, receiver 1 registers the transmitted light and receiver 2 the 90° scattered light. If transmitter 2 is active, it is reversed. An exact turbidity value is determined from the four measured values of a measuring cycle. Since a transmitted light reference measurement value is also available for each 90° scattered light measurement value, disturbing factors such as contamination of the optics or component aging are automatically compensated. Interfering influences from sporadically occurring solids and air bubbles are suppressed by evaluating several measuring cycles and an adjustable filter. The ITM-4 is integrated in a ring-shaped fitting that can be installed in pipes from DN25 to DN100 or DN1″ to DN4″ by means of a hygienic screw fitting or clamp connection.

This measuring method is also used for the ITM-4DW. In this variant, the material for the sensor is specially adapted and approved for drinking water applications but is therefore less expensive than the ITM-4.

What means hygienic design for turbidity sensors?

The turbidity sensors of the ITM series are designed according to international standards for food processing equipment such as 3-A, EHEDG and FDA. This includes the avoidance of dead-legs and the easy cleaning. The entire sensor from the wetted parts to the housing are made of the highest quality materials:

• Components in contact with the medium: stainless steel 1.4404 (316L)
• Optics: Sapphire
• Optical block: PEEK (ITM-4) or PPSU (ITM-4DW)

Thanks to their extremely robust and durable long-life design and, for example, the use of an LED light source, the sensors can withstand even the highest mechanical stresses such as vibrations and pressure surges, which occur repeatedly in many real-world applications, and ensure the highest accuracy, durability and cleanability.

Which process adaptations or installations are possible for turbidity sensors?

A large number of different process adaptations ensure great flexibility with regard to installation in new plants and retrofitting in existing processes. The compact ITM-51 is front flush and can be easily integrated into the process via hygienic screw or clamp fittings. Adapters are also available for existing process connections. A remote version is also available, which ensures optimum adaptation to on-site and technical constraints. Both ITM-4 and ITM-4DW are equipped with a ring-shaped measuring sensor integrated in a housing. This can be easily integrated into pipes of various nominal diameters by means of hygienic screw or clamp connections.