What is the Difference between a Level Switch and a Level Transmitter

Level sensing is integral to many industries that use fluids for their operations. However, the fluid level can significantly affect the result or cause negative consequences for people and the environment. To protect against this, industry users commonly employ level switches and transmitters. These devices provide accurate measurements of the fluid’s level and help to avoid unwanted incidents.

Level Switch & Level Transmitter

But how do these two level-sensing devices differ, and how can you decide which is the right one for your application? A level switch is a device that operates by sensing the fluid level and turning it off or on, depending on the result. On the other hand, a level transmitter works by continuously measuring the level and transmitting data to a controller.

Choosing the right level monitoring solution for your application can take time and effort. This blog will explore the differences between each device and help you decide which is best for your needs.

What is a Level Switch?

The level switches, also known as level sensors, work with an electric contact (reed switch) and a magnetic float. The movement of the float opens or closes the electrical connection.It is mainly used to detect the position of the liquid and monitor and control the liquid level in the industrial production process. There are various types of liquid level switches, the common ones are float type, capacitive type, ultrasonic type and pressure type. Each type has its own unique working principle and application scenario.

Level switch


What is a Level Transmitter?

Level transmitters are an instrument that provides continuous level measurement and can be used to determine the level of a given liquid or bulk solid at any given time. In contrast, point-level sensors indicate whether the substance is above or below the sensing point.There are various types of level transmitters, such as input level transmitters, which can convert the changes of various level parameters into standard current signals and transmit them remotely to the operation and control room for centralized display, alarm or automatic control by secondary instruments or computers.

Level Transmitter

Working Principle: Level Switch VS Level Transmitter

The working principle of a level switch is easy to understand as it works just like an alarm switch. When the fluid level reaches a predetermined level, either above or below, the switch is activated, and a user gets an alert in the form of a sound or other type of notification. The output of a level switch can either be voltage-dependent or voltage-free and may have a fixed voltage of 0-12 volts. This makes it a reliable and easy-to-use device, offering a quick response to any changes in the fluid level.

The level transmitter is equipped with a variable output signal ranging from 4-20 mA, which accurately represents the tank’s capacity. For instance, when the tank is 20 meters high, the level transmitter will output 20 mA when the tank is full, 4 mA when the tank is empty, and 10 mA when the tank is at half capacity. Additionally, these devices can provide point measurements or continuously monitor the level of the tank.

Essential Factors to Consider During Selection

  1. Level transmitters and level switches are invaluable tools for accurate, reliable measurements of liquids. A level transmitter is perfect for applications where the fluid level must be measured precisely. On the other hand, a level switch is an ideal solution when extremely low or high levels need to be monitored. These devices help prevent costly problems such as leaks, overfills, and dry conditions. Level switches and level transmitters are further divided into point-level and continuous-level transmitters. Conversely, continuous-level sensors include submersible level sensors, ultrasonic level sensors, and capacitive level sensors.
  2. Pressure and Temperature.The effects of temperature and pressure on transmitters or level switches may vary drastically if the material transitions from one state to another. Understanding the temperature and pressure impact on a particular material is essential before selecting it for your application. Different materials and designs may have distinct responses to temperature and pressure changes, so choosing the right product for your needs is necessary. Doing so ensures that the transmitter or level switch will be optimally calibrated to the prevailing temperature and pressure conditions.
  3. Range of Measurement. Continuous level transmitters are essential for accurately measuring and monitoring the levels of dry or liquid materials within a wide range. They provide a constant output that lets users quickly understand how much substance is present. These transmitters also produce an analog output to show the exact fluid level in the container, which is far more accurate than level switches, which are only suited for point measurements. With continuous-level transmitters, users can confidently monitor and measure their materials with reliability and accuracy.
  4. Type of Output. Level switches and transmitters are ideal for producing various outputs, including relays, analog, and digital. With the flexibility to easily switch between these outputs, these devices provide an efficient and reliable solution for your application requirements.
  5. Chemical Compatibility. These level-sensing devices may be used with a variety of liquid media. At times, the transmitter’s housing may contact the media, affecting its integrity. It is crucial to address the concern of the impact of different chemical media on sensors.
  6. Tank Size and Shape: The choice of level-sensing device may also depend on the tank size and shape. Extra narrow or vast tanks may have specific requirements.

These factors will assist you in making the right choice. In spite of knowing these factors and your application requirements, partnering with a trusted supplier such as BCST is still recommended.

Applications for Level Switches and Level Transmitters

level switch

The level switch has a variety of applications, such as automatic control, safety protection, and flow control. For example, it can be used as an alarm interlocking device for liquid level monitoring of storage tanks and other vessels. When the liquid level reaches the preset upper and lower limits, the level switch can trigger an alarm or take corresponding control measures to ensure the safety and stability of the production process.

Overall, the level switch is an important industrial automation equipment, which can realize the precise detection and control of the liquid position and improve the production efficiency and safety. When choosing a level switch, you need to make comprehensive consideration according to the specific application scenarios and requirements, and choose the suitable level switch type and specifications.

Level Transmitter

Level transmitter is widely used in the detection and control of various industrial processes, especially suitable for continuous detection of liquid level under special conditions such as high temperature, high pressure, strong corrosion, easy crystallization, clogging, freezing, solid powder, granular materials and so on. It can be applied to water plants, sewage treatment plants, city water supply, high-rise pools, wells, mines, industrial pools, water tanks, oil tanks and other occasions for liquid level measurement and control.

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