Float less water level sensors are an efficient method to measure tank level for several reasons.


  • Float less design is typically a non contact technology which eliminates the requirement of material compatibility between the liquid and the float since there is no float.
  • Float less design also ensures there are no issues with viscous medias coating floats and causing them to fail.
  • Float less level sensors are by default a no moving parts technology, therefore there is no risk for mechanical failures that occur in float based sensors.
  • Float less and non contact level sensors are smaller by design which reduces shipping cost and transit time compared to large stem and float-based sensors.
  • Float less level sensors small design also reduces installation time and the amount of personnel needed to install.

Float Less Level Sensors for Liquids can be broken down into a few main sensing technologies, Radar, Capacitance, and Ultrasonic to name a few.



Radar non contact level sensors work by sending out short microwave signals toward the liquid via the sensor.  The microwave signal then hits the liquid surface and bounces back toward the sensor.  The sensor utilizes the time-of-flight principle which uses the known speed of the microwave, and the time it took for the signal to return, divided by two (since it had to travel down to the liquid and then back up to the sensor) to determine the distance between the liquid level and the sensor.  Since most level is based on the height of the liquid, not the height of the non-liquid (air), the air height is subtracted from the total tank depth to determine the liquid level!


Capacitance level sensors work by using two electrodes within the sensor that form a capacitor.  The capacitor will then process capacitance based on the dielectric constant of the liquid as it encounters the sensor.  The liquid media will have a higher dielectric constant than the air in the tank and will thus increase the capacitance.  This increase in capacitance triggers the sensor to change outputs and thus detect liquid level. 


Ultrasonic level sensors work by emitting sound waves at a high frequency towards the liquid.  The sound waves then reflect off the liquid and the sensor uses the known speed of sound to calculate the distance.  Similarly, to Radar, since most level is based on the height of the liquid, not the height of the non-liquid (air), the air height is subtracted from the total tank depth to determine the liquid level.  Sound waves are slower than microwaves so ultrasonic signals can be affected by high moisture, vapors, and debris in the air.



View Gems’ Float Less Level Sensors for Liquids


RLI-80 Radar Non Contact Level Sensor for Liquids



  • Non-contact
  • 2" NPT mounting
  • PVDF housing
  • Intrinsically Safe
  • UL/c-UL
  • ATEX
  • IECEx
  • 50’ (15m) sensing range
  • 0.2” (5mm) accuracy
  • Modbus
  • 4-20mA
  • Bluetooth®
  • IP 67
  • 15' or 30' TPE Jacketed Cable
  • 1 ¼”-12 For Bracket Mounting
  • Full vacuum to 43 PSI
  • -40 to 80C.



Part Number Chart
Part NumberOutputMountingCable LengthPrice
RLI-80-C-1-14-20 mA
2" NPT
15 feet (4.57m)
RLI-80-C-1-2Modbus2"NPT30 feet (9.14m)
RLI-80-C-2-14-20mA2"NPT15 feet (4.57m)$799.00
RLI-80-C-2-2Modbus2"NPT30 feet (9.14m)$839.00


universal Level Sensor

Gems Universal Water Level Tank Sensor ULS-100


  • Compact – The Universal Level Sensor’s small footprint and less-intrusive flush sensing element for maximum flexibility.
  • Reliable – Accurate and repeatable point-level detection using advanced sensing technology with electronic solid-state switching.
  • Durable – Universal Level can withstand harsh conditions and outdoor environments with IP6k9k rating, wide temperature range, and high-pressure capability
  • Versatile – Reduces inventory and simplifies product selection by replacing several different sensor types with the Universal Level Sensor for aqueous, oil, and hydrocarbon-based media
  • Approvals – * CE, RoHS, UL, cUL
                                                                                      *Approvals Pending


Comparison chart

Universal Level technology encapsulates the best of what existing sensor types offer in a single sensor technology.



  • Non-contact
  • 2" NPT mounting
  • PVDF housing
  • 26’ (8m) sensing range
  • 0.2” (5mm) accuracy
  • 4-20mA
  • IP 65
  • ½” NPT Conduit
  • 30 PSI
  • -40 to 71C.



  • Non-contact
  • 1" NPT mounting
  • PVDF housing
  • 49” (1.25 m) sensing range
  • 0.125” (3 mm) accuracy
  • 48” Cable
  • 1 ¼”-12 For Bracket Mounting
  • 30 PSI
  • -40 to 80C.