Key Features Of The SLS-SA Submersible Level Sensor
Silicon Piezo-Resistive Sensing
An isolated-diaphragm silicon element gives high sensitivity and accuracy, including on shallow ranges from 0.5 mWG.316 Stainless Steel Housing
A corrosion-resistant body for long service in water and compatible liquids.Submersible To 100 m
A high-integrity cable gland and PUR cable give IP68 protection for permanent submersion.Choice Of Analog Outputs
4-20 mA, 0-5 V, 0-10 V, 0.5-4.5 V ratiometric or raw millivolt.Accuracy To ±0.10% FS
Three accuracy classes with 16-bit digital linearization and temperature compensation.Optional Temperature Output
Monitor liquid temperature alongside level from the same sensor.
Applications For Analog Submersible Level Sensors
The SLS-SA suits level measurement wherever a sensor can be lowered into the liquid:
- Rivers, reservoirs and boreholes – continuous water level monitoring in open water and groundwater.
- Tank, IBC and tote level – hydrostatic level measurement in storage vessels.
- V-notch weir flow measurement – accurate head measurement for open-channel flow.
- Environmental monitoring – long-term level records for hydrology studies.
- Flood defense monitoring – early warning and research on rising water levels.
- Telemetry and data logging – 4-20 mA and low-power outputs for remote stations.
- Academic research – field and laboratory studies.
How A Submersible Level Sensor Measures Depth
A submersible level sensor works on the hydrostatic principle: the pressure at the bottom of a column of liquid is proportional to its height. The SLS-SA is lowered to a fixed point below the surface, where its diaphragm senses the pressure of the liquid above. For water, every meter of depth adds about 0.098 bar (1.42 psi).
Atmospheric pressure also acts on the liquid surface, so the cable contains a vent tube that carries air pressure to the back of the sensing element. This cancels out barometric changes and gives a true level reading. The vent tube should end in a dry location, such as a vented junction box, to keep moisture out.
Output Options And Supply Voltages
| Output | Wiring | Supply Voltage | Current |
|---|---|---|---|
| 4-20 mA | 2-wire | 8 to 32 VDC | Signal dependent |
| 0-5 V or 0-10 V | 3-wire | 12 to 32 VDC | 6 mA |
| 0.5-4.5 V ratiometric | 3-wire | 2.7 to 5.5 VDC | 2.5 mA |
| Raw millivolt | Passive bridge | For low-power applications | |
Level Ranges
Ranges are specified in meters of water gauge (mWG).
| Range (mWG) | Approx. Depth (ft of water) |
|---|---|
| 0.5 | 1.6 |
| 1 | 3.3 |
| 2.5 | 8.2 |
| 3.5 | 11.5 |
| 5 | 16.4 |
| 10 | 32.8 |
| 20 | 65.6 |
| 30 | 98.4 |
| 50 | 164 |
| 100 | 328 |
SLS-SA Submersible Level Sensor Technical Specifications
| Specification | Detail |
|---|---|
| Product Type | Submersible hydrostatic level sensor, analog output |
| Sensor Technology | Silicon piezo-resistive, isolated diaphragm |
| Level Ranges | 0.5, 1, 2.5, 3.5, 5, 10, 20, 30, 50, 100 mWG |
| Pressure Reference | Gauge (standard), sealed gauge, absolute |
| Accuracy | ≤ ±0.25%, ≤ ±0.15% or ≤ ±0.10% FS (range dependent) |
| Safe Overpressure | 1.5 x rated range |
| Burst Pressure | 3 x rated range |
| Long Term Stability | ≤ ±0.10% FS |
| Output Options | 4-20 mA (2-wire); 0-5 V, 0-10 V (3-wire); 0.5-4.5 V ratiometric (3-wire); raw millivolt |
| Supply Voltage | 8 to 32 VDC (4-20 mA); 12 to 32 VDC (voltage); 2.7 to 5.5 VDC (ratiometric) |
| Response Time | < 10 ms |
| Thermal Effects | ±0.015% FS/°C typical |
| Temperature Output | Optional |
| Housing And Sensor Material | 316 stainless steel |
| Seals | FKM, EPDM or NBR |
| Compensated Temperature | 0 to +40 °C |
| Media Temperature | -10 to +60 °C, non-freezing |
| Cable | PUR submersible cable with internal vent tube, terminated in tails |
| Cable Connection | G1/4 DIN 3852 male thread when nose cone is unscrewed |
| Ingress Protection | IP68, fully submersible to 100 m |
| Surge Protection | Internal protection; external protection devices recommended |
| Weight | Sensor < 270 g; cable 48 g per meter |
| Conformity | CE |
| Accessories | NPT threaded adaptor, vented junction box, cable hanger |
SLS-SA Submersible Level Sensor FAQs
How deep can the SLS-SA be installed?
The SLS-SA is rated IP68 and can be permanently submerged to a depth of 100 m (328 ft). Choose a level range that covers the maximum height of liquid above the sensor.
Why does the cable have a vent tube?
The vent tube lets atmospheric pressure reach the back of the sensing element so changes in barometric pressure do not affect the level reading. It must end in a dry place, ideally a vented junction box.
What is the difference between the SLS-SA and the SLS-CA?
The SLS-SA uses a silicon sensing element in 316 stainless steel and offers ranges from 0.5 mWG with accuracy to ±0.10% FS. The SLS-CA uses a ceramic sensing element for more aggressive liquids and is also available in marine bronze.
Which output should I choose?
4-20 mA is best for long cable runs and PLC inputs. Voltage outputs suit short runs to local controllers, and the ratiometric and millivolt versions suit battery-powered loggers.