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Capacitance Level Detection in Storage Tanks with Fish Oil

A fish feed manufacturer based in Denmark was looking for a consistently precise, yet simple, user-friendly level monitoring for its fish oil storage tanks.

In addition to being used as a lubricant, leather tanning and, due to its omega-3 fats, as a food supplement, fish oil is mainly used in the manufacture of pet food and for aquaculture. Fish farming, as a rapidly growing global industry, necessitates plant operators to continuously optimize their production technologies and processes. In the storage processes, the robust, capacitive RF rod probe proved to be the optimal solution for the fish feed manufacturer thanks to the precise surface detection and automatic calibration capabilities of the device.

Modern sensors with the capacitive measuring principle

Capacitance RFnivo® for reliable full reporting in tanks with fish oil. The foam that develops during filling can be ignored by the sensor and does not affect the measurement result.
Capacitance RFnivo® for reliable full reporting in tanks with fish oil.
The foam that develops during filling can be ignored by the sensor and does not affect the measurement result.
The foam that develops during filling can be ignored by the sensor and does not affect the measurement result.

In the case of pasty, liquid or viscous media, the capacitive measuring systems offered by UWT GmbH are suitable for overfill prevention and as demand and empty indicators in process and storage containers. The high sensitivity, food-grade design and the variety of brackets make them the ideal solution in various applications in the food industry. As part of the modernization of its content monitoring, the plant operator, who has been producing fish feed for fresh and saltwater aquaculture for over 50 years, decided to equip his fish oil storage processes with the capacitance RFnivo® rod sensor in order to reliably monitor the fill levels. Together with the Danish partner DANOVA ApS from Rude, UWT carried out tests in advance within the tanks to be equipped.

The fish feed manufacturer produces total of 30 different types of fish across 60 countries, which in turn involves the provision of a diverse range of feed. Each type of feed is adapted to the special nutritional needs of the respective fish species and thus a mixture of carefully selected raw materials. In addition to vegetable ingredients, fish oil from harmless and stable stocks is added to the pellets and granules.

Precise overfill protection unaffected by foam

The storage tanks have a diameter of 3 meters and are 11 meters high. Average process temperatures up to 80°C and pressure of up to 0.8bar prevails inside the tanks. The DK value of the fish oil to be measured is in the range 2.0 – 3.0. In order to avoid container overflow, a reliable measurement is crucial for the application, taking into account the frequent formation of foam during filling. The installed RFnivo® sensor with a length of 750 mm and a probe made of 1.4404 stainless steel proved to be a process-compatible solution for monitoring oil storage. The integrated “Active Shield” technology as standard in the RF probe also ensures that the measurement result is not influenced in the long term by buildup or foam.

By equipping the total of 6 tanks with a reliable full monitoring system, permanent protection against overfilling of the fish oil tanks could be guaranteed.  This in turn ensured optimal support of a smooth and maintenance-free manufacturing process for the fish feed manufacturer.

Easy installation and automatic calibration

The RFnivo® calibrated itself after installation when the power supply was connected. Modifying the system or changing process conditions easily dealt with.  By simply pressing a button, the sensor automatically adjusts to the changed situation in question.

The all-voltage electronics is equipped with an easy to read display and 3 control buttons and offers a DPDT relay output for signal evaluation. During operation, the current capacity is always shown on the display. Parameters such as FSH (fail save high) and FSL (fail save low) as well as response time of the signal output can be clearly set in a quick start menu. The operating system integrated within the capacitive level switch can be handled easily by the system operator and does not require any previous or programming knowledge.

Experts in Level Measurement

Based in the Allgäu for more than the past 40 years, UWT is the leading manufacturer of level measurement technology on the world market. The company is principally focused on the field of bulk solids and liquids. Its head office, development and production facilities are located in the Allgäu. With an additional production facility in Malta and its own sales subsidiaries in the United States, United Kingdom, Russia and in the growth regions of China and India, the company can meet the needs of the world market with the greatest flexibility that customers expect. The company is certified ISO 9001:2015 and constantly expands its portfolio of product certifications (ATEX, FM, CSA), particularly with regard to the international markets. The products feature easy handling, high reliability and long service life under the motto of the company “Brilliantly simple level measurement in bulk solids.”

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Level measurement technology at the highest level LEVEL. UP TO THE MAX. UWT GmbH in Betzigau is the expert in level measurement technology and a reliable, world leading solution provider for the safe and accurate...

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