IP68 Submersible Design
Hermetically sealed stainless steel body rated for continuous deep immersion in water and compatible fluids.
Level Instruments
Hydrostatic Level Transmitter
Model FLD-HLT
Accurate. Reliable. Built to perform.
The FlowDo Hydrostatic Level Transmitter is designed for continuous level measurement of liquids in tanks, reservoirs, sumps and open channels. It uses a piezoresistive silicon sensor to measure the hydrostatic pressure proportional to the liquid column.
IP68
Protection
4–20 mA
Output
SS 316L
Sensor
12–36 V DC
Supply
Product Overview
Continuous Submersible Liquid Level Sensing
Precision piezoresistive pressure measurement engineered for open channels, sumps, reservoirs, and deep storage tanks.
The FlowDo FLD-HLT Hydrostatic Level Transmitter is an IP68 fully submersible level measurement instrument. It is lowered directly into the measured liquid to sense the hydrostatic head pressure exerted by the fluid column above its stainless steel diaphragm.
Using a high-stability piezoresistive isolated silicon sensor with a vented polyurethane cable, the transmitter automatically compensates for atmospheric pressure changes. The internal ASIC signal conditioner linearizes and converts the sensed pressure into a calibrated 4–20 mA DC current loop signal.
Key Engineering Highlights
- IP68 fully submersible waterproof construction for continuous liquid immersion
- Corrosion-resistant SS316L stainless steel sensing diaphragm and housing
- Atmospheric pressure compensation via internal vent tube in shielded PUR cable
- Standard 2-wire 4–20 mA DC analog current loop with reverse polarity protection
- Standard measuring spans from 0–1 m up to 0–200 meters water column
Product design
Key Features
Engineered for continuous submersible liquid level monitoring in challenging environments.
SS316L Sensor Diaphragm
High-grade isolated stainless steel sensing element resistant to chemical corrosion and industrial wear.
Wide Range Options
Available in configurable measuring spans from 0–1 meter for sumps up to 0–200 meters for deep borewells.
Vented Cable Technology
Specialized PUR cable with built-in atmospheric vent tube ensures automatic barometric pressure balancing.
Standard 4–20 mA Loop
2-wire loop powered analog output provides high noise immunity and long-distance cable run transmission.
Zero Maintenance
Solid-state piezoresistive sensing with zero moving parts, floats, or mechanical linkages.
Verified catalogue data
Technical Specifications
Technical parameters for FlowDo FLD-HLT Hydrostatic Level Transmitters.
Product Name
Hydrostatic Level Transmitter
Model
FLD-HLT
Sensor Type
Piezoresistive Silicon Sensor (SS 316L Diaphragm)
Measuring Range
0–1 m to 0–200 m H₂O (Custom ranges available)
Output Signal
4–20 mA DC (2-Wire Current Loop)
Power Supply
12–36 V DC (Nominal 24 V DC)
Accuracy
±0.25% F.S. (Standard) / ±0.5% F.S. (Optional)
Operating Temperature
-20°C to +80°C
Compensated Temp. Range
0°C to +50°C
Enclosure Protection
IP68 (Fully Submersible)
Housing Material
SS 304 / SS 316L Stainless Steel
Cable Material
PUR / PVC with Internal Atmospheric Vent Tube
Overpressure Limit
150% to 200% of Full Scale
Industries and processes
Applications
Submersible continuous level monitoring across water utility, industrial, and municipal infrastructure.
Water Storage Tanks & Reservoirs
Continuous level monitoring in overhead water tanks, municipal reservoirs, and industrial raw water storage.
Deep Wells & Borewells
Groundwater level monitoring and pump protection in deep wells, borewells, and extraction shafts.
Wastewater Sumps & Lift Stations
Submersible level control in sewage lift stations, storm water sumps, and industrial ETP equalization basins.
Open Channels & Rivers
Hydrological monitoring, flood warning systems, and open water channel level tracking.
Industrial Cooling Towers
Continuous basin level monitoring and makeup water pump automation in industrial cooling water loops.
Firefighting Water Tanks
Continuous level telemetry in industrial fire water storage reservoirs and emergency pump stations.
System Integration
From Submerged Sensor to Plant Control
Seamless signal transmission from field hydrostatic measurement to central automation architecture.
Hydrostatic Level Transmitter
Submerged IP68 Field Sensor
↓
Continuous Head Pressure
Piezoresistive Liquid Column Sensing
↓
4–20 mA Current Loop
Standard 2-Wire Industrial Signal
↓
Local Indicator
FlowDo Level / Process Indicator
PLC / Controller
Pump Automation & Alarm Logic
↓
SCADA & Plant Monitoring
Real-time telemetry, automated pump interlocks & analytics
Level Technology Overview
Choose the Right Continuous Level Technology
Comparison of primary FlowDo continuous level measurement instruments.
Hydrostatic Level Transmitter
- Principle
- Liquid hydrostatic pressure
- Installation
- Submerged / pressure sensing
- Process Contact
- Yes (sensor exposed to liquid)
- Best Considered For
- Deep sumps, reservoirs, borewells, and open storage tanks.
Ultrasonic Level Transmitter
- Principle
- Sound-wave / acoustic echo
- Installation
- Tank top
- Process Contact
- Non-contact
- Best Considered For
- Compatible open/closed tanks where ultrasonic conditions are suitable.
Radar Level Transmitter
- Principle
- Electromagnetic radar / microwave
- Installation
- Tank top (Flanged / Horn antenna)
- Process Contact
- Non-contact
- Best Considered For
- Challenging process vessels, storage tanks, and non-contact continuous monitoring.
Side Mounted Level Transmitter
- Principle
- Direct-coupled magnetic float / sensing
- Installation
- Tank side nozzle / chamber
- Process Contact
- Sensor wetted assembly in liquid chamber
- Best Considered For
- Tanks with accessible side connections or restricted top access.
Technology selection should consider medium characteristics, tank geometry, installation access, measurement range, temperature, pressure, atmosphere and required accuracy.
Product Options
Available models & configurations.
Explore the available Hydrostatic Level Transmitter configurations for different industrial level-measurement applications.
Catalogue 1 of 3
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Non-contact ultrasonic transmitter for continuous liquid level measurement in tanks, vessels and industrial water applications.
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Side Mounted Level Transmitter
Side-mounted continuous liquid level transmitter for accessible side process connections in industrial tanks and vessels.
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Radar Level Transmitter
Radar-based transmitter for continuous non-contact level measurement in compatible industrial tanks and vessels.
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Capacitance Level Transmitter
Continuous capacitance-based level measurement for compatible industrial tanks, process liquids and vessels.
View details & specs →Frequently Asked Questions
Hydrostatic Level Transmitter FAQs
Common technical questions regarding hydrostatic liquid level measurement.
What is a hydrostatic level transmitter?
A hydrostatic level transmitter is a submersible pressure transmitter used to measure liquid level in tanks, wells, sumps, reservoirs and open channels based on the hydrostatic pressure created by the fluid column.
How does the transmitter measure level?
The sensor measures the pressure exerted by the liquid above the sensing diaphragm. Because pressure is proportional to liquid height (P = ρgh), the transmitter converts this pressure into a standard 4–20 mA output signal.
Can it be used in open tanks and sumps?
Yes. The FLD-HLT is ideal for open tanks, sumps, water reservoirs, wastewater pits and channels where submersible installation is preferred.
How does atmospheric pressure compensation work?
The submersible cable contains an internal vent tube that connects the rear side of the sensing diaphragm to the atmosphere, automatically canceling out ambient barometric changes.
What power supply is required?
The transmitter operates from a 12–36 V DC loop power supply, with 24 V DC being the standard industrial nominal supply.
Can it connect to PLCs or FlowDo indicators?
Yes. The standard 4–20 mA DC 2-wire output connects directly to industrial PLCs, DCS controllers, SCADA RTUs, and FlowDo digital indicators.
Technical selection
Need help selecting the right range?
Contact FlowDo for technical assistance in choosing the right level range, cable length and accessories for your application.
For faster selection, provide: Tank Height • Measured Medium • Liquid Density • Cable Length Required • Temperature • Output Requirements