Measurement of Pressure and Liquid Level During Food and Beverage Processing

The production and processing of food and beverages is subject to strict laws, regulations, and industry codes. The purpose of these rules and guidelines is to minimize the risk of harm to consumers from products containing potentially foreign matter or bacteria. The use of pressure instruments is an important part of safe food production.

Pressure and level measurements in the food, dairy, beverage and manufacturing industries are required in pipes, filters and tanks. Pressure instruments must be accurate, immune to vibration, able to withstand the temperatures and stresses generated during cleaning, and have dedicated wetted parts. Specific applications include balancing tanks, silos, storage tanks, mixing processes, flavoring systems, pasteurization, emulsification, filling machines, homogenization and more.

Most electronic pressure transmitters use an elastic diaphragm as the pressure transmission element. By using suitable process connections, the pressure transmitter can be installed without gaps and easy to clean. CIP cleaning systems (Clean In Place, also known as cleaning in place) are used to clean the inner surfaces of pipes and storage tanks of liquid and semi-liquid food and beverage processing equipment. Typically only large tanks, kettles or piping systems with smooth surfaces are suitable for this type of cleaning. The “wetted part” of the pressure transmitter is the diaphragm, which is in contact with the medium being measured and must be able to withstand the forces and temperatures generated during CIP cleaning and sterilization. Regular cleaning and a gap-free design reduce the risk of contamination, but the surfaces of wetted parts must also have smooth contours and be free of sharp corners and gaps that can cause media to pool and rot. Typically, this part is made of stainless steel to prevent media from sticking.

The PT124B-217 series clamp-type sanitary pressure transmitter produced by ZHYQ is designed to meet the requirements of most food and beverage industry applications. This series of pressure transmitters are rugged and constructed from stainless steel to provide excellent stability and accuracy over a long service life. The flush diaphragm is suitable for CIP and can be installed directly into the process. Other pressure connections are available according to different requirements.

One method used in the food and beverage industry for continuous liquid level measurement is the hydrostatic method. A liquid at rest cannot withstand either shear deformation or tension. The force between two adjacent parts in still water and the force exerted by the still water on the side wall is mainly pressure. This pressure is called hydrostatic pressure. The column of fluid above the pressure sensor creates hydrostatic pressure, which is a direct indicator of fluid level. The measured value depends on the density of the liquid, which can be entered as a calibration parameter.

ZHYQ’s PT124B-220 series submersible liquid level transmitter is designed for liquid level measurement in a variety of applications. Wetted parts are usually made of 316L stainless steel, making them suitable for immersion in most media. The product works for a long time without leakage and has high stability. The front-end sand-proof cap protects the sensor diaphragm. Special breathable cables that are wear-resistant, oil-resistant, acid-alkali-resistant, and high-strength can be configured according to different uses to ensure that signal transmission is not affected by changes in external liquid pressure.

In the case of an open container, where atmospheric pressure acts on the top of the liquid, a gauge pressure sensor can be used. For closed vessels, two separate gauge pressure transmitters or a single differential pressure transmitter can be used for measurement. Control systems in the food industry often use differential pressure transmitters for liquid measurement due to their ruggedness and simplicity. ZHYQ’s PT124B-35 series differential pressure transmitter adopts high-precision silicon sensor technology and can achieve platinum-level accuracy of ±0.05%. It can be used for static pressures up to 32MPa, providing accurate measurement guarantee for the food and beverage industry.