Level Measurement in the Tank

Tank level measurement in the tank with float switches & more: reliable supply & control

Reliable detection of the tank fill level is of central importance for many industrial processes. It ensures that media such as water, chemicals or oils are always available in the required quantity and without overfilling or dry running. Precise level measurement in the tank enables timely refilling, protects connected pumps and system components, and thus contributes to operational safety.

In addition to pure monitoring, it also supports process optimization. Automatic controls that respond to transmitters or float switches can efficiently regulate filling and withdrawal processes. In this way, downtime can be reduced, costs lowered and the utilization of tanks improved.

Reed Electronics AG offers different solutions for this: from continuous transmitters to float switches in the tank through to complete systems with integrated control. Depending on the application, individual requirements for safety, accuracy and automation can be met.

Tank fill level: monitor, regulate and protect

A tank only performs its function reliably if the level is kept within the defined range at all times. Levels that are too low can cause pumps to run dry or processes to be interrupted. A tank fill level that is too high, on the other hand, carries the risk of overflows and damage to plant equipment.

Level measurement performs a central protective function here. It detects critical states early and automatically initiates the appropriate measures (e.g. refilling when a minimum level is undershot or shutting off the supply when the maximum value is reached). This control not only ensures the supply of the medium, but also increases the safety of operating personnel and the environment.

Depending on the operating environment, different accuracies and safety levels may be required. That is why both simple solutions with switching contacts and complex systems with redundant monitoring levels are available. This allows tank level monitoring to be tailored precisely to the respective application.

Measurement principles compared: continuous vs. limit level

Selecting the appropriate measurement principle depends largely on how detailed the tank fill level is to be recorded and further processed. A basic distinction is made between continuous measurement and limit level measurement. Both approaches have specific strengths and are suitable for different operating conditions.

Continuous transmitters: 0–100% for process control

Transmitters provide a continuous signal over the entire fill range of the tank. This makes it possible to record levels in real time, observe trends and automatically control processes. In practice, the data is often integrated into a PLC or a process control system in order to regulate filling and withdrawal processes precisely. Continuous solutions are particularly useful when:

• precise dosing is required,
• refills need to be planned in good time,
• consumption analyses are to be created

Float switches in the tank: reliable limit levels

Float switches work at specific points. They detect when a defined level is reached and switch a corresponding signal. This simple design is robust, cost-efficient and sufficient for many standard applications. In addition, several switching points can be implemented in one tank to clearly indicate different states such as empty, half-full or full.

The decision between a transmitter and a float switch therefore depends on the application profile: should the entire tank level be monitored continuously, or should only certain thresholds be safeguarded? Both methods can also be combined to achieve particularly high operational reliability.

Tank level indication: display and alarm solutions

Recording the tank fill level is only the first step. Equally important is the clear presentation of the information for operating personnel. Depending on the application, this can be simple visual displays directly on the tank or electronic signals that are forwarded to a central control system.

Classic tank level indicators show the current value as a scale, LED bar or via a display. This enables operating personnel to visually check at any time whether the tank is within the target range. In automated systems, the signal is often transmitted via interfaces such as analogue output signals, digital switching contacts or fieldbus systems.

In addition to pure indication, acoustic or visual warning signals are also common. These signal critical states immediately so that action can be taken in good time. Especially in safety-relevant processes – for example with chemicals or process water – the reliable transmission of these signals plays a decisive role.

This means the level information can be used flexibly: locally for direct control or integrated into higher-level systems for seamless process monitoring.

Complete system solution from a single source

Individual sensors are sufficient in many cases, but for more complex applications complete systems become more important. In addition to transmitters and float switches, Reed also offers complete solutions that combine tank technology, filling, filtration, control and redundant safety elements.

Integrated systems combine the various components into a coordinated unit. The medium is filled into the tank via suitable lines, while sensors monitor the level and a controller automatically regulates refilling. Additional modules such as filters ensure the desired media quality. Redundant safety elements such as additional switches or software-independent protection mechanisms ensure that the tank neither overflows nor runs dry.

Reference: reverse osmosis water supply in a diagnostics system

An example of such a system development is the continuous supply of a diagnostics system with reverse osmosis water. A Reed sensor monitors the level of the reservoir and switches off the supply as soon as the defined maximum is reached. If the tank level drops to the set minimum, filling starts automatically. The water is available at any time in the required quality via a filtered discharge line.

The overall system is additionally equipped with several safety levels that work both software-dependent and software-independent. Even line interruptions or short circuits are detected so that the system is automatically shut down in the event of a fault.

Selection criteria: medium, environment, hygiene, EX/ATEX

To achieve reliable results, both the properties of the medium and the boundary conditions of the system must be taken into account.

Material and connection options (e.g. PVC, PP, PVDF, stainless steel)

Selecting the right material depends directly on the chemical resistance and the physical properties of the medium. For aggressive chemicals, highly resistant plastics such as PVDF or PP make sense, while stainless steel is preferred for applications with high temperatures or hygienic requirements. Cable routing and connection types (such as cable version, connector or terminal box) are also adapted to the environmental conditions.

Interfaces: switching contacts, analogue signals, digital I/O

Integration into existing systems requires compatible interfaces. Float switches usually work with simple switching contacts that can directly control pumps or valves. Continuous transmitters provide analogue output signals or digital interfaces to integrate measurement data into process control systems or controllers. This ensures that the tank level indication is not only readable locally, but can also be used for automated processes.

Special attention is also paid to ATEX or EX requirements when flammable liquids or potentially explosive environments are present. In such cases, specially certified components are used that comply with the relevant safety standards.

Engineering, production & assembly at Reed

In addition to individual components, we also offer comprehensive development and production services. The aim is to design level measurement and tank technology so that they can be optimally integrated into existing processes. Customers benefit from a broad range of engineering expertise, from concept development and material selection through to final assembly.

As part of the engineering process, individual requirements are recorded and translated into concrete solutions. This includes selecting suitable sensors, designing the control logic and integrating additional functions such as overflow protection or filtration. In assembly, Reed relies on lean-oriented processes in order to produce small to medium series economically and with consistent quality.

Thanks to the combination of development, production and assembly, complete system solutions can be realized that are tailored to the specific application. Customers therefore receive not only individual products, but a functional overall concept that takes all safety-relevant aspects into account.

FAQs – Frequently asked questions about tank level measurement

When is a continuous transmitter useful?

When exact values are required across the entire fill range. For example for process control, consumption analysis or automatic dosing. Transmitters provide a continuous signal that can be integrated into control systems or process control systems.

Can float switches and transmitters be combined?

Yes. In safety-critical applications, a continuous sensor is often supplemented by an additional float switch. This creates a redundant system that provides a second safety level in the event of faults.

Which materials are available for level sensors?

Depending on the medium, plastics such as PVC, PP or PVDF as well as stainless steel are used. The selection depends on chemical resistance, temperature requirements and hygiene specifications.

Are solutions also available for potentially explosive areas (EX/ATEX)?

Yes. We offer sensors and switches in EX versions that are suitable for use in potentially explosive environments in accordance with the relevant standards.

Can complete systems for tanks be supplied?

In addition to individual sensors, Reed also develops complete systems. These include, among other things, tanks, filling, filtration, control and safety functions.

What information does Reed need for an inquiry?

Information about the medium, the tank geometry, the temperature and the desired interfaces is helpful. On this basis, a suitable measurement system can be designed and offered.