Reliable level measurement is essential for process safety, inventory control, automation efficiency and continuous production. In tanks, silos, reservoirs and process vessels, measurement instruments must often operate under difficult conditions such as dust, vapor, foam, condensation, pressure, high temperature or aggressive materials.
The ELW 804 Radar Level Transmitter is designed to meet these requirements. As part of the ELW 800 series, ELW 804 uses high-frequency radar technology to measure liquid and solid material levels without contact. This makes it suitable for demanding industrial applications where mechanical contact with the medium is not preferred or where traditional level measurement technologies may be affected by process conditions.
What Is ELW 804?
ELW 804 is a radar type level transmitter used for continuous, non-contact level measurement. It belongs to the ELW 800 series, which includes models such as ELW 801, ELW 802, ELW 803, ELW 804, ELW 1000 and ELW 1200.
The ELW 800 series is designed for measuring liquids, solid particulate materials and aggressive liquids. ELW 804 is especially suitable for applications that require extended measuring capability, strong mechanical design and reliable measurement under harsh process conditions.
Operating Principle
ELW 804 operates by transmitting electromagnetic radar waves from its antenna toward the surface of the liquid or solid material. The material surface reflects these waves back to the antenna.
The transmitter calculates the time required for the radar signal to travel to the material surface and return. By comparing this travel time with the configured vessel height, the device calculates the level inside the tank or silo.
Thanks to the use of two microprocessors and wave-tracking algorithms, the device provides strong signal processing capability for reliable level measurement in industrial environments.
Non-Contact Measurement Advantage
Because ELW 804 measures without direct contact with the process medium, it reduces problems related to mechanical wear, coating, sticking, corrosion or material buildup.
This non-contact measurement principle is especially useful in applications involving aggressive liquids, dusty solids, sticky materials, condensate formation, foam or vapor. The catalog specifically highlights that the ELW 800 series is not affected by foam and vapor and is suitable for use in dusty environments.
Suitable for Liquids and Solid Materials
ELW 804 can be used for both liquids and solid particulate materials. This provides flexibility for facilities that need one radar technology family across different process areas.
Typical applications include chemical plants, pharmaceutical processes, cooling water tanks, food and plastic industries, energy plants, oil facilities, cement factories, petroleum tanks, fire water tanks, rivers, waste material processes and wastewater applications.
Technical Features of ELW 804
ELW 804 operates in the 76–81 GHz frequency range. This high-frequency radar technology supports a narrow beam angle and stable measurement performance.
For ELW 803 and ELW 804 models, the measuring range can reach up to 120 m depending on the application and configuration. The catalog specifies accuracy options of ±3 mm and ±5 mm for the ELW 803/804 group.
The resolution is 1 mm, repeatability is ±1 mm, and response time is less than 2 seconds. The sampling frequency is listed as 54 GHz in the technical table.
Process and Environmental Conditions
ELW 804 is designed for demanding process conditions. The process temperature range for ELW 803 and ELW 804 is listed as -40 °C to +200 °C, while the ambient temperature range is -20 °C to +60 °C.
The working pressure range for the ELW 803/804 group is -1 bar to +20 bar. Relative humidity tolerance is below 95%.
The protection class is IP66 according to EN60529, supporting field installation in industrial environments.
Electrical Output and Communication
ELW 804 uses a 15–36 VDC two-wire power supply and consumes less than 0.5 W.
The standard output signal is 4–20 mA two-wire + HART, with a resolution of 1.6 µA. The catalog also lists configurable error signal values such as 20.5 mA, 22 mA and 3.9 mA, along with a programmable integration time from 0 to 20 seconds.
This allows ELW 804 to be integrated into control systems, PLCs, remote monitoring systems and process automation networks.
Display and Adjustment
The ELW 800 series includes an LCD display for indication and adjustment. The catalog shows a local display with adjustment keys, including back, previous, next and enter/confirm functions.
This interface allows users to configure and monitor the device in the field. The menu language is listed as English.
The product also supports HART communication using a handheld calibrator with a 250 Ω resistor in the loop, enabling practical parameterization and diagnostics in industrial installations.
Mechanical Design and Connections
ELW 804 is available with threaded and flanged mechanical connection options. The catalog lists process connections such as G 1½, G 3, DN50 and DN80 flanged versions for the ELW 801/802/803/804 group.
The antenna type for ELW 803 and ELW 804 is listed as flange lens, with PTFE antenna material. Housing options include aluminum injection housing AlSi12Fe black RAL9005 as standard and plastic housing options.
Connection materials include PTFE, 304 stainless steel and 316 stainless steel, supporting compatibility with different process requirements.
Beam Angle and Measurement Focus
ELW 804 offers beam angle options of 14°, 7° and 3° depending on configuration. A narrower beam angle helps focus the radar signal and can improve measurement stability in tall silos, narrow vessels or applications with internal structures.
This is especially useful in solid material applications where dust, uneven surface formation or vessel geometry can make level measurement more difficult.
Accessories for Harsh Environments
The ELW catalog includes accessories such as a protective cover and cooling adapter.
The protective cover is made from 304 stainless steel, welded and hinged, and is designed to protect the transmitter against external environmental conditions. The cooling adapter is also made from 304 stainless steel and can be applied to all models for process temperatures up to 250 °C.
These accessories help extend the usability of ELW 804 in outdoor installations and high-temperature applications.
Why Choose ELW 804?
ELW 804 is a strong choice for applications that require long-range, non-contact and reliable level measurement. Its radar technology is suitable for both liquids and bulk solids, while its resistance to foam, vapor, dust, sticky materials and condensate formation provides dependable performance in challenging environments.
With HART communication, LCD display, stainless steel and PTFE process material options, high process temperature capability and pressure resistance up to 20 bar, ELW 804 offers a robust solution for industrial process measurement.
Conclusion
The ELW 804 Radar Level Transmitter is a powerful non-contact level measurement solution for liquids, aggressive liquids and solid bulk materials. As part of the ELW 800 series, it combines 76–81 GHz radar technology, high mechanical durability, long measuring range, HART output, LCD adjustment and harsh-environment compatibility.
For industries such as chemical processing, food production, plastics, energy, cement, petroleum, wastewater and bulk solids handling, ELW 804 provides reliable continuous level measurement without direct contact with the process medium.