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RU Flex 2100 Digital Level Sensor

RU Flex 2100 Digital Level Sensor

Categories: Digital Level Sensors (DLS)

The patent-pending RU Flex 2100 DLS is a flexible, extremely rugged, chemically and abrasion resistant digital level sensor offering continuous, accurate, and reliable monitoring of tank level and temperature. With the 36” flexible diameter, one person can install the sensor in 15 minutes. Increased measurement accuracy (3/16" when ordered with 1/8" resolution) makes this sensor ready for API 18.2 custody transfer level measurement requirements.

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(Please include all of the specifications from the Configuration Options below on your RFQ)

The patent-pending RU Flex 2100 DLS is a flexible, extremely rugged, chemically and abrasion resistant digital level sensor offering continuous, accurate, and reliable monitoring of tank level and temperature.

The RU Flex 2100 DLS is built on Electrolab’s proven, patented sensing technology. All electronics are enclosed in a proprietary, patent-pending hose with multi-layer barrier properties for difficult environments. This flexible sensor coils into a 36” diameter allowing for one person to install the sensor safely from a catwalk. ALL sensor components fit in one box, which can ship standard carrier to your location. Increased measurement accuracy, 3/16" when ordered with 1/8" resolution, makes this sensor ready for more API 18.2 custody transfer level measurement requirements.

Reliable— No Ongoing Calibration

After installing the sensor hardware and setting the initial level offset, these sensors require no additional calibration. All electronics, with the exception of those in the sensor housing, are sealed inside the sensor tube. The apparatus is intrinsically safe (when used with a qualified intrinsically Safe Barrier, such as Electrolab’s 2110 Barrier Unit) or explosion-proof when used with the Explosion-Proof Housing (Model 2110EX). The RU Flex 2100 DLS offers low power consumption and is virtually maintenance free.

More Versatile and Reliable than Guided-Wave Radar

Electrolab’s RU Flex 2100 DLS offers greater versatility, flexibility, and more robust features than conventional guided-wave radar (GWR) level sensors. A dual float sensor measures multiple fluid levels and temperature measurements through a SINGLE TANK PORT, eliminating the need for multiple sensors in one tank. To accomplish these same measurement and alarm protections, GWR requires two separate ports in a tank. This single device can also read up to eight distinct temperature measurements.

Unlike radar, this sensor is not affected by electro-mechanical interference, tank turbulence or changing environmental variables. Simply install the sensor, set your initial level offset and the RU Flex 2100 DLS is ready to monitor your tank. Under normal operating conditions, no additional calibration is needed—EVER. Ongoing maintenance is practically non-existent. The naturally oleophobic non-stick nature of the RU Flex hose helps ensure ongoing measurement accuracy by preventing paraffin and other pollutants from building up on the sensor. Cleaning of the RU Flex 2100 DLS is rarely necessary.

Flexible and Easy to Install

The RU Flex 2100 DLS offers all the benefits of Electrolab’s Model 2100 Digital Level Sensor with the added flexibility of a bendable material that can be coiled to a 36” diameter. This means the sensor can fit neatly in a box for shipping and storage. All components (sensor, housing, cord grip, floats, weight and grounding cable) fit neatly inside the same box, reducing the possibility of misplaced pieces. Once arriving at the installation site and assembled, the RU Flex 2100 DLS is easily carried on the shoulder and installed in a tank by one person. A weight, sized based on the length of the sensor and turbulence of the tank, attaches to the bottom of the hose before installation to ensure the sensor straightens out inside the tank and remains straight.

The RU Flex 2100 DLS delivers consistently accurate level and temperature measurements of different types of fluids in both hazardous and non-hazardous environments. With 3/16” accuracy (optional), this sensor is ready to meet API Custody Transfer level measurement requirements. Multiple fluid densities and temperatures do not affect the measurements. The RU Flex 2100 DLS is suitable for production monitoring, inventory control, and leak detection in a variety of different types of storage tanks (crude oil, diesel, kerosene, gasoline, water, and chemical). Communications to SCADA systems can be digital or analog and the DLS works with most wireless systems using Modbus RTU protocols and ASCII.

Hose Material: A proprietary, patent-pending, flexible hose with multi-layer barrier properties for use in difficult environments

Measurement lengths: 2 to 48 feet

Housing: Explosion Proof 2110EX (12V or 24V), L-standard, C, T or no housing

Level Measurement Increments:

  • 1/8-in. resolution; 3/16-in. accuracy
  • 1/4-in. resolution; +/- 1/8-in. accuracy
  • 1/2-in. resolution; +/- 1/4-in. accuracy
  • +/- 0.1% repeatability

Coiled Diameter: Approximately 36-inch diameter (will vary slightly with the length of the sensor)


  • NYTROPHYL stainless steel
  • Two piece floats for field installation and replacement
  • One float used for product level
  • One float for water interface level
  • Designed to fit through a three-inch NFPT tank port

Operating Temperature Range: -40 degrees C to 80 degrees C

Temperature Measurement:

  • 12 inches from bottom
  • +/- 1.5 degrees C accuracy
  • Up to 8 distinct temperature measurements (one standard)

Power Requirements: • 5.6 VDC to 12.9 VDC

Power Consumption: 15 mA nominal 20 mA maximum

Pressure: 40 psi: standard


  • Modbus RTU 16-bit unsigned integer
  • Modbus RTU 32-bit floating point
  • Modbus RTU 2 x 16-bit
  • Serial Data via ASCII

Anchor Weight: 3 in. diameter, required weight varies based on sensor length

Wiring: 18 AWG recommended for digital circuits


Class I, Div. 1, Group D hazardous locations (when used with the Explosion Proof Housing or used with a standard housing and connected to an approved intrinsically safe barrier device)


  • ANSI/UL-913, 7th Edition
  • CAN/CSA C22, No. 157


Open communication protocols allow Electrolab’s RU Flex 2100 DLS to interface with most manufacturers’ equipment. We offer:

  • RS485
  • Two- or four- wire communications
  • Baud rate and parity programmable
  • 4-20mA signal available when connected to an Electrolab 3010 digital-to-analog converter board
  • Wireless compatibility with preferred partners


  • Housing: Explosion Proof (12V or 24V), L (standard), C, T or no housing
  • High Level Shut-In with or without test fixture