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OleumTech Level Sensors and Switches


Low-Power, RS485 Modbus/ASCII Liquid Level Gauges

Float-based, Field-Proven Resistive Reed Switch Technology, US Patent 8,763,455 B1

RL3: Modbus | RL4: LevelMaster ASCII


  • Monitor product, interface, and temperature with a single sensor
  • 2x discrete inputs (RL3 Modbus version only)
  • Sensor option: flex (PTFE) or rigid (316 SS)
  • 1/4” resolution option (±1/8” accuracy)
  • 1/2” resolution option (±1/4“ accuracy)
  • RS485 interface (Modbus or LevelMaster ASCII)
  • Quick and easy to install
  • “Set it and forget it” – no on-going calibration required
  • Supports a wide temperature range: -40 ˚C to 120 ˚C / -40 ˚F to 248 ˚F
  • Multiple fluid compatibility
  • Guaranteed against H2S damage, scaling, and paraffin buildup
  • 6-30 Vdc power input
  • Class I, Division 1 (Zone 0), Intrinsically Safe
  • Click here to see level sensor accessories

OleumTech Level Sensors are Ideal for

Production Tanks | Water Tanks | SWD Locations | Separators | Condensate Tanks
Midstream Collection and Blend Tanks | Refinery Holding Tanks | Chemical Tanks | Many Others


Ultimate Level Sensing Solution

Tried and true is the Resistive Tank Level Sensor by OleumTech®, which is part of the H-Series Sensor line of high quality instruments that deliver unrivaled performance, reliability, and accuracy in extreme, hazardous outdoor conditions.

With over two decades of innovation and manufacturing expertise, OleumTech’s Resistive Level Sensor is the company’s flagship level monitoring solution that offers industry’s leading 5-in-1 monitoring capabilities: product (oil), interface (water), temperature, and two discrete inputs. Discrete inputs are only available on the RL3 Modbus version for connecting to dry contact or open-drain output/NPN sources for notifying state changes.

OleumTech’s patented Resistive Sensors are offered in both flexible (PTFE) and rigid (316 SS) materials in various lengths.

Contact your OleumTech representative to learn more about its high performance automation solutions.


Reliable, Scalable, and Safe

The ultra-high-performance level sensor can communicate with any Modbus master or LevelMaster device via RS485 Serial connection. The low-power Resistive Level Sensor can be multi-dropped of up to 16 sensors. Additional data such as volume and tank full percentage can be calculated and reported as well, along with the core level variables. The Resistive Level Sensor is certified for use in Class I, Division 1 (Zone 0) hazardous locations and is Intrinsically Safe, making it one of the safest product in the world.

Do Much More with Less

The OleumTech Resistive Level Sensor give you the ability to continuously measure product (oil), interface (water), and temperature and monitor two discrete inputs from a single instrument, eliminating the need for multiple sensors and multiple tank ports.

No Wiring Hassle

Every Resistive Level Sensor is equipped with a quick connect fitting that joins the sensor to its head without any wires, eliminating wiring error and hassle to help you save valuable time during installation and troubleshooting.

Installs in Minutes

The flexible (PTFE) level sensor is only 20 inches in diameter when coiled  making extremely easy to transport. Deployment cost and time can be significantly reduced by enabling just one person to perform the entire installation.

High Scalability

Up to 16 of these low-power level sensing instruments can be multi-dropped using a single power supply. There are multiple 3/4-inch NPT ports available on the sensor head to help you run conduit and wire with ease.

Great Peace of Mind

The OleumTech Resistive Level Sensors are Intrinsically Safe and are certified for use in Class I, Division 1 (Zone 0) hazardous locations, providing the highest level of safety under rigorous, extreme outdoor conditions.

Maximum Flexibility

You can choose either Modbus RTU or LevelMaster ASCII communication protocol option for interfacing virtually any existing SCADA or control system. This digital level sensor is also available with wireless options.

Rigid - 316 Stainless Steel

Resistive Level Sensors are available with the rigid 316SS option, ranging from 2 to 21 ft in lengths with multiple float options. The rigid sensor comes equipped with a 3/4-inch NPT 1-inch NPT height adjustable compression fitting.

Flexible - PTFE

The liquid level probes can be ordered with the flexible (Polytetrafluoroethylene) option, ranging from 8 to 38 ft in lengths with multiple float options. This sensor provides a 1-inch NPT height adjustable compression fitting.

Choice is Yours

You can take advantage of the 1/4-inch resolution version of the sensor with ±1/8-inch accuracy or take a more cost-effective approach by using the 1/2-inch resolution version that provides ±1/4-inch accuracy.

Device Functionality∙ Resistive Level Sensor with RS485 Serial Interface
∙ RL3: Modbus, Provides Product, Interface and Temperature Levels + 2 Discrete Inputs
∙ RL4: LevelMaster ASCII, Provides Product, Interface and Temperature Levels
Embedded Controller∙ Ultra-Low Power RISC Microcontroller with Internal FLASH (Field Upgradeable)
Configuration∙ USB to RS485 Converter (SX1000-CC8)
Sensor Type∙ Resistive Reed Switch
Resolution∙ High Resolution, Depends on Sensor: 1/4" (6.4 mm) or 1/2" (12.7 mm)
Accuracy∙ US: ± 1/8-inch for 1/4-inch Resolution Sensor ; ±1/4-inch for 1/2-inch Resolution Sensor
∙ Metric: ± 3.2 mm for 6.4 mm Resolution Sensor ; ±6.4 mm for 12.7 mm Resolution Sensor
Interface∙ RS485 Modbus or LevelMaster ASCII
Baud Rate∙ 1200-115200 bps
Safety∙ Intrinsically Safe for Use in Hazardous Environments
∙ Class I, Division 1, Groups C, D T4; Ex ia IIB T4 Ga; Class I, Zone 0, AEx ia IIB T4 Ga, -40 °C ≤ Tamb ≤ 70 °C
∙ ATEX: Sira 16ATEX2229X; Ex ia IIB T4 Ga, -40 °C ≤ TA ≤ 70 °C
∙ IECEx: SIR 16.0079X; Ex ia IIB T4 Ga, -40 °C ≤ TA ≤ 70 °C
Dimensions∙ 5" (W) x 7.6" (H) x 4.4" (D) / 127 mm (W) x 193 mm (H) x 112 mm (D)
Package Dimensions ∙ 10.25" (W) x 14" (H) x 6.5" (D) / 260 mm (W) x 356 mm (H) x 165 mm (D)
Package Weight∙ ~4.5 lbs/ 2.0 kg (Head Only)
Connection Fitting∙ 3/4" NPT Female
Enclosure Casing Material∙ Type 4X Aluminum; IP66
DC Power Input∙ 6-30 Vdc (30 V Max)
Power Consumption∙ 28.5 mA Maximum / 1.7 mA Idle Current
Multi-Drop Max Consumption∙ 55 mA Maximum based on 16 Sensors Multi-Dropped
IS Safety Protection∙ Barrier Board (See Part Numbers under Ordering Information)
Operating Conditions∙ Sensor: Ambient Temperature (Class I, Division 1): -40 °F to 248 °F (-40 °C to 120 °C)
∙ Transmitter: Ambient Temperature (Class I, Division 1): -40 °F to 158 °F (-40 °C to 70 °C)
∙ Transmitter: Ambient Temperature (Non-Hazardous Applications): -40 °F to 176 °F (-40 °C to 80 °C)
∙ Humidity: 0 to 99 %, Non-Condensing
Warranty∙ 2-Year Parts and Labor
Country of Origin∙ USA
SENSORRIGID: 316 Stainless Steel "SS"FLEX: Polytetrafluoroethylene "PTFE"
TypeExtremely Reliable and Accurate Resistive Reed Switch Technology
Measurement Capabilities (3-in-1)Product, Interface, and Temperature
Lengths Offered in US Units2 to 26 ft Length in 1 ft Increments8 to 38 ft Length in 1 ft Increments
Lengths Offered in Metric0.61 to 7.93 m in 0.31 m increments2.44 to 11.58 m in 0.31 m increments
Resolution and AccuracyOption 1: 1/2-inch (12.7 mm) Resolution with ±1/4-inch ( ±6.4 mm) Accuracy (6-pin Quick Connect)
Option 2: 1/4-inch (6.4 mm) Resolution with ±1/8-inch (±3.2 mm) Accuracy (8-pin Quick Connect)
Sensor to Interface Mating Connection (No Wiring Solution)316 SS Quick Connect: 6-pin Connection for 1/2" Resolution, 8-pin Connection for 1/4" Resolution
Tank Mating Connection (Adjustable Compression Fitting)2-15 ft: 3/4" NPT Male / 16-26 ft: 1" NPT Male1" NPT Male
Temperature Accuracy±1 °C
Sensor Rod/Tubing Diameter0.63" (16 mm): 2-15 ft Sensor0.85" (22 mm)
0.85" (22 mm): 16-26 ft Sensor
Anchor Weight DiameterN/A2.88" / 73 mm
Height of Anchor WeightN/AUp to 26 ft sensor: 4.75" / 121 mm
26 - 38 ft sensor: 8" / 203 mm
Coiled DiameterN/A20" (50.8 cm) Coiled Diameter
Minimum Measurement from Bottom (Deadband)2" (50.8 mm) from BottomFrom Top of Anchor Weight
Sensor Pressure RatingFloat DependentFloat Dependent
316 Stainless Steel - Standard (Included w/Rigid <=15 ft440 PSI / 30 BarN/A
316 Stainless Steel - Large363 PSI / 25 Bar142 PSI / 9.8 Bar
Polypropylene (PP) (Inc. w/Flex and w/Rigid >=16ft72 PSI / 5 Bar72 PSI / 5 Bar
Float Options:
316 Stainless Steel - Standard, 440 PSI/30 BarCompatible Only with Rigid Sensor Length up to 15 ft Prod: 0.64 SG, Intf: 0.96 SG, ID 0.72" (18.3 mm)
OD 2.05" (52.1 mm), Inner Clearance: 0.1" (2.6 mm)
316 Stainless Steel - Large, 363 PSI/25 BarProduct: 0.62 SG, Interface: 0.95 SG, ID 1.1" (27.9 mm), OD 2.76" (70.1 mm), Inner Clearance: 0.5" (12.7 mm)
Polypropylene (PP), 72 PSI/5 BarProduct: 0.64 SG, Interface: 0.96 SG, ID 1.1" (27.9 mm), OD 2.91" (73.9 mm), Inner Clearance: 0.5" (12.7 mm)
Operating Temp. Sensing Area -40 °F to 248 °F (-40 °C to 120 °C)
CertificationsClass I, Division 1, Groups C, D T4; Ex ia IIB T4 Ga; Class I, Zone 0, AEx ia IIB T4 Ga, -40 °C ≤ Tamb ≤ 70 °C
ATEX: Sira 16ATEX2229X; Ex ia IIB T4 Ga, -40 °C ≤ Tamb ≤ 70 °C
IECEx: SIR 16.0079X; Ex ia IIB T4 Ga, -40 °C ≤ Tamb ≤ 70 °C
Power (Wireless)3.6 V Lithium Replaceable Battery Pack, 10-Year Life @ 1 min Read Interval
Power (Hardwired)External 6-30 Vdc (30 V max)
Wireless CompatibilityOTC - WT / SM Series Resistive Transmitters and Sigfox-enabled Resistive Nodes
Hardwire Serial Interface (H-Series Only)RS485, 2-Wire, 16 or 32-bit Modbus RTU, LevelMaster ASCII, Termination for Daisy-chain
Minimum Sensor Read IntervalDown to 5 Seconds
Model #: 1/2" Resolution with ±1/4-inch Accuracy60-4001-xxx60-4101-xxx
Model #:1/4" Resolution with ±1/8-inch Accuracy60-4101-xxx60-4102-xxx
Kit #: 1/2" Resolution with Float(s)ZG-xxx-FxxTG-xxx-Fxx
Kit #: 1/4" Resolution with Float(s)ZH-xxx-FxxTH-xxx-Fxx
Model Numbers∙ 1/2" Resolution (6-pin): HW5000-RL3 (Modbus), HW5000-RL4 (LevelMaster ASCII)
∙ 1/4" Resolution (8-pin): HW5800-RL3 (Modbus), HW5800-RL4 (LevelMaster ASCII)
IS Barrier Boards∙ 12 V Kit: SX1000-B12, 1x RS485 Module (61-6002-001) + 1x 12 V Module (61-6003-001)
∙ 24 V Kit: SX1000-B24, 1x RS485 Module (61-6002-001) + 1x 24 V Module (61-6004-001)
Configuration Kit∙ H-Series Configuration Kit (SX1000-CC8)
Safety∙ Intrinsically Safe for Use in Hazardous Environments
∙ Class I, Division 1, Groups C, D T4; Ex ia IIB T4 Ga; Class I, Zone 0, AEx ia IIB T4 Ga, -40 °C ≤ Tamb ≤ 70 °C
∙ ATEX: Sira 16ATEX2229X; Ex ia IIB T4 Ga, -40 °C ≤ Tamb ≤ 70 °C
∙ IECEx: SIR 16.0079X; Ex ia IIB T4 Ga, -40 °C ≤ Tamb ≤ 70 °C


Wireless Level Sensors

Best-in-class tank level gauge and wireless interface combination for self-contained, battery-powered standalone operation.

Hydrostatic Level Sensors

Cost-effective wireless level monitoring solution using a low-power 1-5 V analog submersible hydrostatic pressure transducer.

High Level Switches

Instantly detect high level conditions for providing overfill  protection and  spills prevention. Detect high and high-high levels.