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Level Control and Measurement

Fluid level control is a mechanism, device, or system which monitors, compares, and regulates the level of liquids or gases within a process to a set value. Level measurement determines the position of the level relative to the top or bottom of the process fluid storage tank or silo. Level control and measurement are essential to assuring the safety and profitability of industrial processes.

Fluid level control

The level measurement is a measurement of fluid level, the measure of height is called a level. The measurement of level is essential in a process, ensuring safety. The level measurement is categorized into the top-down and bottom-up levels.

The top-down measurement is not susceptible to leakage, and it can be considered a less leakage process. The top-down measurement can contact the fluid, while the bottom-up type ensures contact with the process fluid. The level measurement is not only done for fluids; it is also used to measure gases and solids.

Direct level measurement

The direct level measurement is an easy process; this measurement is based on physical principles such as fluid motions, floats, and thermal properties.

Indirect level measurement

The indirect level measurement is done by measuring other quantities such as volume. This method measures level by determining other parameters such as pressure, weight, or temperature.

Measuring and monitoring fluid levels accurately and precisely requires choosing the correct methodology for the target vessel. Generally, there are six methods for measuring and monitoring fluid levels, namely:

  • Continuous float level transmitters
  • Differential pressure transmitters
  • Radar level transmitters
  • Ultrasonic level transmitter
  • Load cells
  • Radio Frequency

Continuous Float Level Transmitters

These level monitors operate using a float suspended in the fluid from a rod, something of a dip-stick, which sends a vibration up the rod to a sensor.

Differential pressure transmitters

Differential pressure transmitters can be used to determine fluid levels by determining the difference in head pressure between the low-pressure port and the high-pressure port in its usual configuration.

Radar Level Transmitters

Radar is a non-contact method that entails bouncing an electromagnetic pulse off a fluid surface and measuring the time required to return to the sensor.

Ultrasonic level transmitter

Like radar, Ultrasonic sensors are less sensitive to medium characteristics and vessel construction.

Load cells

A load cell is a transducer technique that measures weight, a mechanical force, or a load and creates an output signal which relays data to be extrapolated into a fluid level.

Radio Frequency

RF technology uses the electrical characteristics of capacitors in a vessel to map the contours of the surface area.


Fluid level sensors, or liquid level sensors, are used to monitor and regulate levels of a particular free-flowing substance within a space. These substances are usually liquid; however, liquid level sensors can also be used to monitor solids, such as powders. There are many different types of liquid level sensors, and they have several uses.

Basic fluid level sensors can identify the point at which a liquid falls below a minimum or rises above a maximum level. Many liquid level sensors can detail the specific amount of liquid in a container relative to the minimum/maximum levels to continuously measure volume.

Fluid level sensors are the sensors used for detecting liquid levels or interfaces between liquids such as water and oil or solids. These sensors can also be defined as transducers or integrated systems with instrumentation and control capabilities. This type of liquid level sensor is one of the most critical sensors and plays an essential role in various industrial and consumer applications.

The most straightforward industrial level measurement device is the sight glass, a manual approach to measurement, not without its limitations. The material used for its transparency can suffer failure, with ensuing environmental insult, hazardous conditions for personnel, and fire and explosion. Seals are prone to leak, obscuring the visible level, and more advanced technologies are rapidly replacing them.

Other level-detection devices include those based on specific gravity, the physical property most commonly used to sense the level surface. A simple float with a specific gravity between the process fluid and the headspace vapor will float at the surface, accurately following its characteristics. Hydrostatic head measurements have also been widely used to infer levels.

When more complex physical principles are involved, emerging technologies often use high-end computers to perform the calculations. This requires sending data from the sensor to the control or monitoring system. Practical transducer output signal formats for computer automation are current loops, analog voltages, and digital signals. Analog voltages are simple to set up and deal with but may have severe noise and interference issues.

Point level measurement

Capacitance level sensors

The capacitance level sensors are operated by using a probe for checking changes in the level. These level changes are converted into analog signals. Most commonly, the examinations consist of conducting wire by PTFE insulation.

Optical Level Sensors

The optical sensors work based on the changes of transmission in infrared light emitted from an IR LED. By using a high-energy IR diode and pulse modulation methods, the interference from the produced light can be reduced.

Continuous Level Measurement Sensors

Industrial ultrasonic level sensors

Industrial ultrasonic sensors are also used to detect the levels of sticky liquid substances and bulkiness materials. They work by emitting and receiving ultrasonic waves at roughly 20 to 200 kHz.

Radar (Microwave) Sensors

The operation of radar or microwave sensors is similar to ultrasonic. But, the pulses travel at the speed of light. The repeatability and reliability can be exaggerated, but this time by the dielectric constant of the fluid.

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Experts for Level Control and Measurement

As product manager at UWT Nikolas specializes in solving demanding applications, consulting, training and troubleshooting. He also studied industrial engineering, technical product and innovation management. Since coming to UWT in 2018 he found his passion for level measurement solutions for different process situations in a variety of industries. He enjoys new, exciting challenges and he is our go-to expert on tricky installations around the globe. PERFORMANCE. UP TO THE MAX. That’s what motivates him. Markus started out his career by training as a Systems Electronics Technician where he acquired valuable practical experiences in this field. He then moved on to study at the University of Ulster (Northern Ireland) and the University of Applied Sciences Kempten (Germany) where he graduated as an Electronics Engineer. Since then, he has gained over 20 years’ experience in product management, application consulting and product training working for international operating companies specializing in measurement and control devices. During that time Markus has worked with various sensor technologies in the field of flow, pressure and level control providing innovative solutions for organisations around the globe. Currently his professional focus is on level measurement, especially vibration, capacitive and radio frequency technologies. In addition he also specializes in rotary paddle, guided and free radar devices. With his extensive experience within the industry Markus is renowned as an expert in all applications delivering solutions from the standard through to extreme measurement situations as well as the more unusual niche applications.
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Ryan Fitzgerald, Product Manager at Anderson-Negele, is an expert for the process management sensor portfolio which includes electromagnetic flow meters, Coriolis flow meters, temperature sensors and pressure sensors. He has spent the past years turning customer pain points into innovative sensing and measurement solutions. Given Anderson-Negele’s global 90+ year focus in the hygienic industry Ryan also has a vast knowledge of hygienic/sanitary design standards and requirements that apply to sensors primarily used in the Food & Beverage and Life Science industries. After completing a BS in Mechanical Engineering at Clarkson University Ryan joined the Team at Anderson-Negele in Fultonville NY. Ryan has developed technical product and application knowledge throughout his career through roles in design and application engineering. A passion for understanding and solving customer problems led Ryan to his current position as product manager at Anderson-Negele.
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Natalie Waldecker, Portfolio Manager Food and Pharma, knows the challenges of the demanding industries inside out. With her broad application knowledge, she is at home on topics such as hygiene design, certificates and cleanability. As product manager for pressure measurement technology, she is also responsible for one of the most important measuring principles for the industry. Natalie gathers her knowledge as close to the application as possible. Preferably directly at the customer’s site, experiencing “real world” practice. She has thus gotten thoroughly acquainted with international customer requirements and knows the ins and outs of the market. With this background, she is able to not only explain technical relationships in an understandable way, but also offer valuable tips and convincing solutions. In the 12 years she has been with VEGA, she has steadily improved her expertise which makes her the right person to contact for new product ideas and tailored customer solutions.
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