OleumTech Hardwired Sensors and Switches


Low-Power Liquid Level Gauges (Modbus or LevelMaster)

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

HW-RL3: Modbus | HW-RL4: LevelMaster


  • Monitor product, interface, and temperature
    with a single sensor
  • 2 discrete inputs (HW-RL3 Modbus version only)
  • 1/4” resolution option (±1/8” accuracy)*
    *API 18.2-compliant
  • 1/2” resolution option (±1/4“ accuracy)
  • Sensor option: flex (PTFE) or rigid (316 SS)
  • Multiple liquid compatibility
  • Modbus RS485 interface (Modbus or LevelMaster ASCII)
  • Quick and easy to install
  • Sensor only requires a one-time calibration
  • Supports a wide temperature range
    -40 ˚C to 120 ˚C (-40 ˚F to 248 ˚F)
  • Highly resistant to H2S damage, scaling, and paraffin buildup (Limited lifetime warranty, please contact your OleumTech representative
    for details)
  • 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

The RS485 Resistive Tank Level Sensors by OleumTech® are part of the H Series line of high quality instruments that deliver unrivaled performance, reliability, and accuracy in hazardous locations as well as under harsh, extreme environmental conditions.

With over two decades of innovation and manufacturing expertise, OleumTech’s Resistive Level Sensors are the company’s flagship level monitoring solution that offers industry’s leading 3-in-1 monitoring capabilities: product (oil), interface (water), and temperature. Furthermore, the HW-RL3 RS485 Modbus Transmitter is equipped with two discrete inputs for connecting to dry contact sources delivering 5-in-1 monitoring capabilities. The HW-RL3 also has the ability to calculate and report volume and tank full percentage data.

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

Reliable, Scalable, and Safe

The H Series ultra-high-performance level gauging solution can communicate with any Modbus master or LevelMaster device via RS485 Serial connection. The low-power Resistive Level Sensors can be multi-dropped of up to 16 devices. The Resistive Level Sensors are certified for use in Class I, Division 1 (Zone 0) hazardous locations and are Intrinsically Safe, making them one of the safest products in the world.

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

This product is also available with a local display.

This product is also available in wireless.

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 (HW-RL3 only) 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 for ultrafast installs and gives ability to program on or off the tanks.

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∙ H Series RS485 Transmitter with Support for Resistive Level Sensors
∙ HW-RL3: Modbus, Provides Product, Interface and Temperature Levels + 2 Discrete Inputs
∙ HW-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" for 1/4" Resolution Sensor ; ±1/4" for 1/2" Resolution Sensor
∙ Metric: ± 3.2 mm for 6.4 mm Resolution Sensor ; ±6.4 mm for 12.7 mm Resolution Sensor
2 Discrete Inputs∙ Dry Contact, NPN (Sink), Debounce Filter 20 - 2000 ms (Available on HW-RL3)
Interface∙ RS485 Modbus or LevelMaster ASCII
Baud Rate∙ 1200-115,200 bps
Safety∙ Intrinsically Safe for Use in Hazardous Environments
∙ Class I Division 1, Class l, Group A, B, C, D, Zone 0, Ex ia llC T4, AEx ia llC T4 Ga
∙ ATEX: Sira 16ATEX2229X; Ex ia IIC T4 Ga
∙ IECEx: SIR 16.0079X; Ex ia IIC T4 Ga
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) (9-30 Vdc recommended for best performance)
Power Consumption∙ 25 mA Maximum / 1.2 mA Idle Current
Multi-Drop Max Consumption∙ 54 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 °C to 120 °C (-40 °F to 248 °F)
∙ Transmitter: Ambient Temperature (Class I, Division 1): -40 °C to 70 °C (-40 °F to 158 °F)
∙ Transmitter: Ambient Temperature (Non-Hazardous Applications): -40 °C to 80 °C (-40 °F to 176 °F)
∙ Humidity: 0 to 99 %, Non-Condensing
Warranty∙ 2-Year Parts and Labor
Country of Origin∙ USA
SENSORRIGID: 316 Stainless Steel "SS"FLEX: Polytetrfluoroethylene "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 7.9 m in 0.31 m increments2.44 to 11.58 m in 0.31 m increments
Resolution and AccuracyOption 1: 1/2" (12.7 mm) Resolution with ±1/4" ( ±6.4 mm) Accuracy (6-pin Quick Connect)
Option 2: 1/4" (6.4 mm) Resolution with ±1/8" (±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)3/4" NPT Male1" NPT Male
Temperature Accuracy±1 °C
Anchor Weight DiameterN/A2.4" / 60.3 mm
Height of Anchor WeightN/A8 to 19 ft Sensor: 5"
20 - 28 ft Sensor: 6.75" / 29 - 38 ft Sensor: 8"
Coiled DiameterN/A20" (50.8 cm) Coiled Diameter
Minimum Measurement from Bottom (Deadband)2" (50.8 mm) from BottomFrom Top of Anchor Weight
Pressure RatingFloat DependentFloat Dependent
Sensor Only without Float(s)569 PSI (39 Bar)142 PSI (9.8 Bar)
Sensor w/ 316 SS Float - Small (for Rigid Sensors 7 ft and below only)440 PSI (30 Bar)N/A
Sensor w/ Polyvinylidene Fluoride (PVDF) Float72.5 PSI (5 Bar)72.5 PSI (5 Bar)
Float Options:
*316 Stainless Steel - Small, (Fx0)Compatible Only with Rigid Sensor Length up to 7 ft
Product: 0.64 SG, Interface: 0.96 SG, ID 0.72" (18.3 mm), OD 2.05" (52.1 mm), H 2.71” (68.83 mm)
316 Stainless Steel - Large, (Fx1)Product: 0.62 SG, Interface: 0.95 SG, ID 1.12" (28.5 +/-0.5 mm), OD 2.83" (72 mm), H 4.65” (118 +/-1 mm)
Polyvinylidene Fluoride (PVDF), (Fx3)Product: 0.64 SG, Interface: 0.96 SG, ID 1.18" (30 +0.3/-0 mm), OD 2.83" (72 +/-0.25 mm), H 1.77” (45 +/-1 mm)
Operating Temp. Sensing Area-40 °C to 120 °C (-40 °F to 248 °F)
CertificationsClass I, Division 1, Groups C, D T4; Ex ia IIB T4 Ga; Class I, Zone 0, AEx ia IIC T4 Ga
ATEX: Sira 16ATEX2229X; Ex ia IIC T4 Ga
IECEx: SIR 16.0079X; Ex ia IIC T4 Ga
Device CompatibilityOleumTech WT, SM, and H Series Resistive Level Transmitters
PowerThe Sensor is Powered by the Transmitter
Kit Ordering #: 1/2" Resolution with Float(s)ZGxxxFxxTGxxxFxx
Kit Ordering #: 1/4" Resolution with Float(s)ZHxxxFxxTHxxxFxx
Transmitters∙ 1/2" Resolution (6-pin): HW5000-RL3 (Modbus), HW5000-RL4 (LevelMaster ASCII)
∙ 1/4" Resolution (8-pin): HW5800-RL3 (Modbus), HW5800-RL4 (LevelMaster ASCII)
Level Sensor Kits∙ 1/2" Resolution Kits (6-pin): Rigid: ZGxxxFxx, TGxxxFxx (xxx = Length in Inches, Fxx = Float Configuration)
∙ 1/4" Resolution Kits (8-pin): Rigid: ZHxxxFxx, THxxxFxx (xxx = Length in Inches, Fxx = Float Configuration)
IS Barrier Boards∙ 12 V Kit: SX1000-B12, RS485 Module (61-6002-001) + 12 V Module (61-6003-001)
∙ 24 V Kit: SX1000-B24, RS485 Module (61-6002-001) + 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, Class l, Group A, B, C, D, Zone 0, Ex ia llC T4, AEx ia llC T4 Ga
∙ ATEX: Sira 16ATEX2229X; Ex ia IIB T4 Ga
∙ IECEx: SIR 16.0079X; Ex ia IIB T4 Ga