Continuous level sensors are used to measure the level within a specific range and provide continuous monitoring of level conditions.

With a wide variety of approaches to point level and continuous level measurement of liquids and solids,  Sigma Hellas can assist to solve the needs in many level applications. The sensors and systems we offer are based on the following measuring methods:

• RF capacitance
• Capacitive
• Hydrostatic
• Radar
• Ultrasonic
• Laser

Level Transmitter Overview

Radar Level Transmitters

Unlike conventional through-air radar (also known as FMCW – Frequency Modulated Continuous Wave), Guided Waves Radar  utilizes a wave-guide to direct or guide very low power microwave pulses. FMCW radar sensors emit higher frequency microwave pulses through-air to reflect from the product surface.

Guided Waves Radar directs a pulse down a probe that is reflected at the material to be measured. Transit time is measured and level calculated. Use of a probe or wave-guide permits very efficient energy transmission, use of compact, low power electronics resulting in higher efficiency and lower costs.

700 series Guided Wave Radar

Bulk Solids Level Transmitter

The 700 series uses guided wave radar to make measurements, which means no moving parts and therefore, virtually no maintenance. A waveguide directs the microwave pulses, eliminating the beam divergence problems common to conventional non -contact radar transmitters.

Model 701 with a stainless steel cable probe is designed specifically for bulk solids in Silos.

FEATURES
Radar Signal Travels Along the Waveguide –
Eliminates False Echoes and Minimizes Signal Loss
No Moving Parts
2 Wire Loop Powered
Linearization Table
Lengths up to 30 meters
Flexible Cable Probes
Remote Display (optional)
IP68 Protection rating
All Digital Electronics
EXiaIICT6

OPTIONS

• HART Protocol
• 316L Stainless Steel Enclosure
• Remote display

SPECIFICATIONS

Housing Aluminum or Stainless Steel

Power 18 – 30 VDC

Wiring Standard - 2 wire

Output Single 4-20 mA, HART

Accuracy ±1mm

Resolution +/- 0.063 in / 1.6 mm

Range up to 30 meters (­exible probe)

Sensor Material 316L SS Standard

Process Pressure -1.0 to 40bar

Process Temperature from -40C up to +250C (-20…150C standard)

Housing rating IP68

Dielectric Constant 1.3-2.3; 3-100 Direct Mode

Model, Probe,                           Length,             Material

701       8mm cable probe          30000mm         Stainless steel

702       10mm rod probe            6000mm           Stainless steel

703       Two-rods probe             6000mm           Stainless steel (Flange mounting)

900 series 26G Radar Level Transmitter for solids

A non-contact, microprocessor controlled Radar Level Transmitter for solids, easy to install and maintain digital level instrument. 900 series 26G Radar Level Transmitter can measure up to the maximum span of 70 meters.

Benefits
● Small antenna size, easy to install; Non-contact radar, no wear, no pollution.
● Corrosion resistant, bubble effect; almost not affected by water vapor in the atmosphere, the temperature and pressure changes.
● Dusty environment has little effect.
●With aA shorter wavelength, the reflection of solid surface inclination is better.
● Beam angle is small, the energy is concentrated, can enhance the ability of echo and to avoid interference.

Technical Characteristics
Measurement Span: 0 to 70 meters
15m/20m/35m (powder);
20m/30m/45m (particle);
35m/45m/55m(lump materials)
0-1m...70m(liquids)
Signal Output: 4...20mA/HART (2 wires/4 wires) RS485/Modbus
Process Connection: Multidirectional flange
Medium Temperature: -40~250℃
Process Pressure: -1Bar~1 Bar
Accuracy: ±15mm
IP rating: IP67
Power supply: DC24V or 85-265VAC
Frequency Span: up to 26G Hz
Explosion proof rating: Exib ⅡCT6 Gb

Applications :
● Solid materials
● Process container or strong dust
● Radar with purging function
● Condensation occasions
● Liquids with foam
● Powders

Sigma R2000 80GHz High Accuracy Radar Level Sensor for Liquids

Sigma R2000 is a 80GHz mmWave radar level sensor. Its advanced radar technology and user-friendly PC interface ensure precise measurements, high sensitivity, and seamless integration. This non-contact sensor offers contamination-free, low-maintenance level monitoring solutions. Its compatibility with control systems allows for effortless integration into industrial processes, enabling remote monitoring and control, ideal for various industrial applications.

Features
● ±2mm/5mm/10mm accuracy with a wide detection range
● Advanced radar technology, unaffected by condensation, rain, vapor, corrosion, dielectric constants...
● Easily connects to host computers & tank-side meters with dedicated software
● A wide power supply range and minimized power consumption
● A top-mounted bubble level design for straightforward setup
● On-site calibration not required

Technical Characteristics
Working pressure: -1~3bar
Measuring range: 0.2-10m
Measurement accuracy: ±10mm(typical), ±2mm/±5mm(customized)
Frequency: 80GHz
Signal output: 12-30Vdc: 0-5V/0-10V/4-20mA+RS485 Modbus RTU
3.3-4.2Vdc: RS485 Modbus RTU only
Power Supply: 12-30Vdc(Typical)
3.3-4.2Vdc(Low voltage & low power consumption type)
Working temperature: -40~85℃
Protection rating: IP67/IP68(3 bar) optional
Material of wet parts: PVDF(Anti-corrosion type)
Material of housing: PA6 nylon + Fiberglass

Applications:
●Water & Sewage treatment
●Oil & gas industry
●Hydrological & flooding monitoring
●Pharmaceutical industry
●Food and beverage manufacturing
●Chemical industry
●Process control

Hydrostatic Head

One of the oldest and most common methods of measuring liquid level is to measure the pressure exerted by a column (or head) of liquid in the vessel. We offer solutions with submersible sensors and through the tank wall sensor options.

400 series

The 400 series of submersible pressure transmitters includes a number of completely submersible pressure-sensing transmitter models ranging  from 0 to 1m water column to 0 to 500m, that contain an air vent tube for providing a pressure differential relationship between the hydrostatic head and the atmosphere. The transducer contains associated electronic circuitry for providing an analogue output, has an IP 68 protection rating, and requires a  24 Vdc ± 10% Power Supply
These transmitters can be used in applications such as:
• Tank Level Measurement
• Level measurement of liquids with foams
• Level measurement of muddy liquids
• Well / borehole Level Monitoring
• Surface Water Monitoring
• Hydraulic monitoring in rivers and seas
• Reservoirs
• Research
• Water treatment

Laser Sensors

All Digital Designs that Combine Accuracy and Speed for Non-Contact, Continuous Level Measurement. Applications Include: Pellets (Converters), Slurries, Opaque Liquids and tall Bin and Silos.

Ultrasonic Level sensors –  a non contact technology

Ultrasonic sensors provide a cost effective sensing method with unique properties not possessed by other sensing technologies. By using a wide variety of ultrasonic transducers and several different frequency ranges, an ultrasonic sensor can be designed to solve many application problems that are cost prohibitive or simply cannot be solved by other sensors. Ultrasonic sensors continuously emit high frequency sound pulses inaudible to the human ear  which travel away from the sensor, hit the surface of the target and are reflected back to the sensor. The sensor electronics measure the time taken by the signals to return after being reflected by the target surface.

Since the speed of sound is affected by air temperature, our ultrasonic sensors include a built-in temperature sensor. Level/distance measurements are automatically temperature compensated throughout the operating temperature range of the sensor.

Sigma has a variety of sensors available to satisfy the requirements of most applications including Micro, a compact, ultrasonic level transmitter/switch that features Variable GAP technology that allows the instrument to work even in the presence of dust, vapour or foam. Variable GAP ensures accurate measurements by always working with the smallest return signal.

Sigma U3003 Ultrasonic Level Sensor

Sigma U3003 is an ultrasonic level sensor. It offers accurate non-contact liquid level and distance measurement using sound waves. With its compact design and high accuracy, it is suitable for various applications. It features reverse polarity protection, surge lightning protection, anti-obstacle interference and provides reliable and real-time data, making it a versatile solution for monitoring liquid levels in tanks and containers.

Features
● 0-50℃ wide automatic temperature compensation
● Advanced algorithm adopted, not affected by low temperature
● 2.5m, 5m, 10m, 15m wide measuring ranges with small blind area
● Up to 0.25%F.S accuracy customized
● Short response time, power-off self-recovery function
● IP67 high protection rating, IP68 can be optional

Technical Characteristics
● Measuring range: 2.5m, 5m, 10m, 15m, others on request
● Blind area: 4-20mA(2.5m/5m):≤150mm
0-5v(2.5m/5m):≤200mm
4-20mA/0-5V(10m):≤300mm
4-20mA/0-5V(15m):≤500mm
● Accuracy: 0.5%F.S (typical), 0.25%F.S (by customized)
● Output signal: RS485+4~20mA; RS485+0~5V
● Power supply: 10~30VDC(24VDC recommended, 5~30VDC by customized)
● Working temperature: -10~50℃(-40~80℃ by customized)
● IP rating: IP67 typical, IP68 by customized

Applications
Water, Oil, Diesel Level Measurement, Tank Pump Control
Treatment Plants
Food Industry
Chemical Industry
Rivers, Channels, Lakes, Flooding Monitoring

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