• Proven Flexar™ Technology Installed in Thousands Of Bulk Solids Applications
  • Reliable TDR (a.k.a Reflex Radar) Technology Used for Decades
  • "Smart" Transmitter Output For Use with Industry-Leading SiloTrack™ Inventory Management Software
  • SiloTrack™ Software Is Network-Ready - Virtually Unlimited Users (Local & Remote)
  • Measuring Range up to 100 ft (30.5 m) in Solids and 200 ft (61 m) in Liquids
  • Unaffected by Airborne Dust, Bulk Density, Temperature, and Other Properties - Ideal for Powders and Pneumatically-Filled Solids
  • Process Temperatures up to +392 ºF (200 ºC)
  • No Field Calibration Required - Easy to Install and Setup
  • Optional Analog Output for Easy Connection to Existing Control Systems or Indicating Devices
  • Hazardous Location Approvals Available
When All The Pieces Fit Just Right!
The Flexar™ continuous level measurement system is a smart-guided, wave radar device used for monitoring the level of powders, granules, and other bulk solids. It is also suitable for use with a multiplicity of liquids. It is used in a wide assortment of vessels and industries for measuring levels up to 200 ft (61 m) in height.

Bringing the Pieces Together: Manufactured at our facility in Elburn, IL, we uniquely combine this proven and strategically-acquired technology with almost five decades of expertise and focus in powder and bulk solids applications, and with our SiloTrack™ inventory management software interface. Monitor Technologies uniquely provides the best solutions in level measurement and inventory management of powders and bulk solids.

The Flexar™ guided, wave radar level sensor and/or transmitter requires no field calibration or re-calibration and can be set up easily by customer personnel without the use of special tools or training. Flexar™ units are suited for almost any application, can operate with process temperatures up to 392º F (200ºC), can be provided with a variety of process connections and work reliably with materials having a wide range of bulk densities and dielectric constants.

Flexar™ is available with a choice of two outputs. The standard output is a "smart" interface for use with SiloTrack™ Version 3.5 PC-based inventory management software. This network-ready software provides a flexible graphical interface for up to 128 "smart" output sensors. In lieu of this "smart" output, an optional analog output is also available.

Consult Monitor Technologies factory for all applications prior to pricing and issuing quotation.
Unit of Measure


Electronics Type

N/A Integral Electronics


N/A "Smart" RS-485 (For use with SiloTrack V3.5 and higher)
Probe Type1 N/A Single Cable, Stainless Steel, 0.16" (4 mm) diameter
Approvals2 N/A Hazardous Location CSA US/C (North America)

Operating Voltage

N/A Low Voltage (24 VAC/VDC)
Probe Connection3 N/A 1 1/2 NPT Threaded


N/A For 0.31" (8 mm) single cable, large CW

Power Requirements

N/A 24 VAC/VDC (+10 %/-15 %); 9 VA/W

Max. Altitude

N/A 6562 ft2000 m

Installation Category


Pollution Degree

N/A 4 (Reduced to 2 by enclosure) Suitable for indoor/outdoor use

Process Temperature

N/A -20º to 392 ºF-30º to 200 ºC

Ambient Temperature

N/A -5º to 120 ºF-20º to 50 ºC

Operating Pressure

N/A -14.5 to 580 psig-1 to 40 bar

Measurement Range

N/A 150 ft45 m


N/A ≥ 20ft (6m): ± 0.2” (5mm) + 0.02% of distance measured < 20ft (6m): ± 0.2” (5mm) ± 0.8” (20mm) Direct Mode Liquids: Direct Mode Solids: TBF Mode (All): ± 0.8” (20mm) when Dielectric is constant


N/A ± 0.04 in± 1 mm


N/A ± 0.012 in± 0.3 mm

Min. Dielectric Constant

N/A Direct Mode: Twin Cable ≥ 1.8; Single Cable/Rod ≥ 2.1 TBF Mode: All Probe Styles ≥ 1.4

Process Mounting Connection

N/A All probe Styles: 2” ANSI 150lb. Flange; DN50PN40 Flange Single Cable/Rod Only: 1 1/2 NPT; G 1 1/2 (1 1/2 BSP)

Conduit / Cable Entry

N/A BSP/DN Process Connections: (2) M20 x 1.5 cable connectors NPT/ANSI Process Connections: (2) 1/2 NPT

Max. Traction Loading

N/A 2250 lb1.02 t1.1 t

Min. Separaton from Objects

N/A 12 in300 mm

Output Signal

N/A RS-485, half-duplex, isolated, proprietary protocol

Wiring Distance

N/A 4000 ft1220 m

Local Display

N/A 3-line; Backlit LCD; 3 pushbuttons; 3 magnetic sensors for setup without cover removal

Enclosure Material

N/A Aluminum, Powder Coated

Threaded / Flange Connection Material

N/A 316 Stainless Steel

Process Insulator Material

N/A Teflon (PTFE)

O-Ring Seal Material

N/A Viton

Probe Material

N/A 316 Stainless Steel

Dead Zones (Top) - Dielectric = 80 (Water)

N/A 15.75 in400 mm

Dead Zones (Bottom) - Dielectric = 80 (Water)

N/A 0.8 in20 mm

Dead Zones (Top) - Dielectric = 2.4 (Oil)

N/A 19.7 in500 mm

Dead Zones (Bottom) - Dielectric = 2.4 (Oil)

N/A 3.9 in100 mm

Enclosure Rating

N/A NEMA 4, IP66


N/A CSA US/C Class I, Div 1,2, Groups B, C, D; Class II, Div 1,2, Groups E, F, G; Class III; ATEX ll 1/2 GDT75...150C (pending)


Weight of Enclosure (without Probe for Ordinary Location)

N/A 18 lb8 kg

Weight of Enclosure (without Probe for Hazardous Location)

N/A 20 lb9 kg


N/A 0.08 lb/ft0.12 kg/m

Principle of Operation

N/A Flexar® smart guided wave radar level sensors and transmitters operate using TDR (time domain reflectometry) principles that were first developed in the middle part of the 20th century for use in the geological field. Further development of TDR led to its use in the telecommunication industry for detecting breaks in cables. Flexar technology was pioneered in the mid-late 1990’s when TDR was applied to level measuring applications within the process measurement industry.

In the application of TDR for process level measurement micro-pulses are continuously transmitted along a probe or “wave guide” at the speed of light. As soon as the pulses reach the material surface they reflect back to the sensor electronics unit. The time-of-flight of the pulses is calculated and directly related to the distance from the point at which the sensor is mounted on the top of the vessel to the material surface (level). The output from the electronics is continuously updated as the level of the material surface changes.

Flexar smart guided wave radar sensors are equipped with two different measuring modes. In the Direct measuring mode the pulses directly reflect off the material surface back to the electronics unit. This mode is used in applications where the material being measured has a dielectric constant as low as 2.1 for single-cable/rod probes and 1.8 for twin-cable probes.

For materials with dielectric constant below the above mentioned limits, down to as low as 1.4, the second measurement mode is used. This is the TBF (tank bottom following) mode, which is used due to the inability of the pulses to adequately reflect off of the surface of very low dielectric materials. In this measuring mode the Flexar sensor has a “short circuit” at the bottom of the probe at a precisely known distance from the sensor’s mounting point.

In the TBF mode the pulses travel through air at the speed of light and then pass through the material in the vessel at a slower speed, dependent on the specific dielectric constant. The pulses are reflected at the short circuit back up the probe. Flexar sensors in the TBF mode measure the time between the emission and reception of the pulses from the probe short circuit. Because the return time of a pulse when no material is present (through air) is known, we can determine the difference in time between the time-of-flight when empty and the time-of-flight when filled as being directly proportional to the material level in the vessel.


N/A The Flexar® smart guided wave radar continuous level measuring system can be used in a wide variety of applications, including powders, coarse/fine granular solids, liquids, foodstuffs and even some corrosive substances. Flexar sensor technology is proven in many difficult applications including those where dust levels make it difficult for other technologies to perform reliably, especially at long ranges.

Typical Applications include, but are not limited to:

  • Feeds
  • Cement
  • Coal Dust
  • Lime
  • Powders
  • Grains
  • Carbon Black
  • Silica
  • Bulk Chemicals
  • Plastic Pellets
  • Aggregates
  • Oils
  • Fly Ash
  • Flour
  • PVC Powder
The maximum range for solids applications is limited to 100ft (30m) due to load limits possible from heavy materials in long ranges. Liquid applications can extend up to 200ft (60m). Any application requiring a continuous level measurement update where the process temperature does not exceed 392° F (200°C) and 580psig (40bar) is possible. The 316 stainless steel probes and threaded or flanged process connections make the Flexar continuous level measuring system ideal for almost any bulk solid and liquid application. To ensure a successful and reliable application, consult with the Monitor Technologies factory-based technical support group to see if Flexar is right for your application.

Remote Inventory Monitoring

N/A If material levels need to be monitored at one or many locations (i.e. your facility, a location down the street, or a plant on the other side of the world) the Flexar system can provide continuous, reliable and accurate measurements. Using SiloTrack™ Version 3.5 software, inventory monitoring from remote locations has never been easier.


N/A Solid-State Performance, No Moving Parts.
Unlike weight and cable based systems of old, Flexar® guided wave radar level sensors are state-of-the-art and use a time-proven electronic method for continuous measurement of a material level. This non-mechanical means of measurement helps ensure low maintenance.

Measure Materials With Dielectric > 1.4 (TBF Mode).
Flexar sensors are capable of sensing and measuring the level of most any material. Materials with dielectric constants below 1.8-2.1 require the use of our TBF (tank bottom following) measuring mode.

Unaffected By Dust And Changes In Material Properties.
The technology employed in Flexar units has been proven to be unaffected by airborne dust even during pneumatic filling operations. Unlike through-air technologies such as ultrasonic, through-air radar and laser, Flexar can reliably measure in dusty environments without sacrificing performance or reliability.

Range Of Probes.
In order to handle the assortment of applications possible with Flexar, Monitor offers a range of probe styles including single-cable, twin-cable and single-rod. All probes are constructed of 316 stainless steel, have traction load handling capabilities suitable for their respective applications and are easily field replaceable. Consult with Monitor’s factory-based technical support personnel to select the right probe style for your application.

Assortment Of Process Connections.
To meet the required bulk solids and liquid applications we have prepared a selection of process connections that will ensure a smooth and simple installation. Flexar sensors can be provided with 1-1/2” NPT, 1-1/2” BSP G, 2” ANSI or DIN DN50PN40 flange connections. Probe type will determine the available process connections.

Dual Compartment Enclosure.
The Flexar smart guided wave radar sensor uses an enclosure with two compartments, each with its own access cover. This allows separation of access for wiring and setup/display. The setup/display compartment is provided with a cover window allowing local viewing of the LCD display. In addition, every unit is provided with either two 1/2” NPT conduit entrances (NPT threaded and ANSI flanged process connections) or M20 cable connectors (BSP threaded and DN flanged process connections).

Local LCD Display And Setup.
Each sensor includes a built-in user interface consisting of a three-line backlit LCD display, three pushbuttons and three magnetic sensors (used to perform setup and interact with the unit without having to remove the display cover).

Universal Power Supply.
Power supply choices include a universal high voltage option 100-240 VAC and a low voltage 24 VAC/VDC option.

Choice of outputs.
The standard output for all Flexar guided wave radar units is a “smart” RS-485 communications interface for use with SiloTrack™ Version 3.5 inventory management software. In lieu of this “smart” interface an analog 4-20mA output is available.

Remote electronics available.
The standard unit includes the electronics integrally mounted with the sensor. However, remote mounted electronics is optionally available for applications where the electronics are desired to be mounted away from the probe due to extreme vibration, temperature or for convenient access to the local operator interface. The remote electronics version includes a pre-wired 16.4ft (5m) interconnecting cable

Hazardous location approvals available.
All units include the CE mark and are approved for use in ordinary locations. When required, Flexar sensors can be provided approved for use in hazardous areas worldwide. Flexar is available with ATEX and CSA US/C approvals for hazardous areas.

PC-Based Inventory Management Software

N/A SiloTrack™ Version 3.5 Inventory Management Software provides users with an unsurpassed, flexible graphical interface for Flexar® smart guided wave radar sensors. Together, SiloTrack Server and Client software can provide inventory monitoring and management to a virtually unlimited number of users, both internal and external to your facility. This allows easy implementation of remote monitoring and vendor managed inventory programs.

SiloTrack capabilities include:

  • Monitor up to 128 sensors/with up to 5 sensors per vessel
  • Easy to setup and use
  • Network-ready
  • Remote monitoring via LAN, Internet/WAN or dial-up
  • Available in English/Spanish language
  • Automatic and manual measurement initiation
  • Curve-fit weight table
  • Enhanced 3-D type silo graphics
  • Export silo history and alarm data
  • Automatic Reports and Scheduling
  • Set up four alarms per silo
  • Alarm notification via e-mail, fax, and/or pager
Power Requirements: 100 - 240 VAC


N/A Monitor Technologies LLC warrants each Flexar® guided wave radar continuous level measurement system and HMI2 it manufactures to be free from defects in material and workmanship under normal use and service within two (2) years from the date of purchase. The purchaser must give notice of any defect to Monitor within the warranty period, return the product intact and pre-paid transportation charges. The obligation of Monitor Technologies LLC under warranty is limited to repair or replacement at its factory. This warranty shall not apply to any product which is repaired or altered outside of the Monitor Technologies LLC factory, or which has been subject to misuse, negligence, accident, incorrect wiring by others or improper installation.

Monitor Technologies LLC reserves the right to change the design and/or specifications with our prior notice.

  • 1 Customer specified length is from the bottom of the process connection to the bottom of the counterweight (end of rod on single rod probes).
  • 2 Hazardous Location approval of Remote Electronics version is "pending". Consult Factory.
  • 3 Availability of G 1-1/2 threaded process connection is "pending". Consult factory.
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