Model WL400 - Water Level Sensor



Global Water's WL400 Water Level Sensor provides highly accurate water level measurement for a wide variety of applications, including those in severe environments. The submersible pressure transducers have a dynamic temperature compensation system, enabling high accuracy measurements over a wide temperature range. The water level sensor is easily adapted to all dataloggers, telemetry, monitoring equipment, and displays.

Each of the water level sensors consist of a solid state submersible pressure transducer encapsulated in a stainless steel 13/16 inch diameter housing. The water level sensor has a molded-on waterproof cable and a two-wire 4-20 mA high level output for connection to a monitoring device. A 25 ft cable is standard, and optional cable lengths are available up to 500 ft.

The Water Level Sensor's submersible pressure transducer is fully encapsulated with marine-grade epoxy so that moisture can never leak in or work its way down the vent tube to cause drift or level sensor failure (as is the case with other pressure sensors). The water level sensor uses a unique, highly flexible silicon diaphragm to interface between water and the sensing element. This silicon diaphragm protects the water level sensor's electronics from moisture and provides each sensor with exceptional linearity and very low hysteresis. The design of the submersible pressure transducers eliminates the issues associated with metal foil diaphragms, which tend to crinkle and stretch out over time causing drift, linearity, and hysteresis problems. The water level sensor is also has automatically barometric compensation due to the attached vent cable and protected by a stainless steel micro-screen cap, which makes fouling with silt, mud, or sludge virtually impossible. The water level sensor's design is great for all saltwater applications including tide level monitoring, floating docks, and others.

Pressure transducer level ranges of 0-3, 0-15, 0-30, 0-60, 0-120, 0-250, and 0-500 feet are available. The 0-3 ft low-level range is ideal for measuring shallow flows or small water level changes like those encountered in sewers, storm drains, weirs, and flumes. The 0-3 ft water monitoring sensor accurately measures small changes in water, even when the water's depth is only a few inches deep. Other metal foil-type water level sensors typically have serious problems at low-level ranges because of sensor crinkling, stretching, and drifting.

Each submersible pressure transducer has a two-wire 4-20 mA output signal that is linear with water depth. From 10 to 36 VDC is required to operate the water level sensor, so the level sensors can be operated from common 12 VDC battery systems. The 4-20 mA signal can run up to 3,000 ft from the submersible pressure transducer to the logging device. Common twisted pair or electrical extension cord wire may be spliced to the vented cable once the cable is out of the water. The 4-20 mA signal may be converted to 0.5 to 2.5 VDC by dropping the current signal across a 125 ohm resistor.

  • High accuracy and reliability
  • Completely submersible pressure transducer and cable
  • Compact, rugged design for easy installation
  • Minimal maintenance and care
  • Water level sensor compatible with most monitoring equipment
  • 4-20mA output
  • Vented cable for automatic barometric compensation
  • Multiple level ranges available from 3' to 500'
  • Wet-wet water level sensor eliminates vent tube concerns
  • Dynamic temperature compensation system
  • Submersible pressure transducer not affected by foam, wind, or rain
  • Monitors levels in groundwater wells, rivers, streams, tanks, lift stations and open channels
  • CE Certified

Sensing Element

  • Sensor Element: Silicone Diaphragm, Wet/Wet Transducer
  • Pressure Range: 0-3, 0-15, 0-30, 0-60, 0-120, 0-250, 0-500 ft
  • Linearity and Hysteresis: ±0.1% FS
  • Accuracy: ±0.1% of full scale at constant temperature, ±0.2% over 35°F to 70°F (1.37° to 21.1°C) range
  • Overpressure: Not to exceed 2 x full scale range
  • Resolution: Infinitesimal (Analog)
  • Outputs: 4-20 mA or 0.5 to 2.5 VDC across 125 ohms
  • Supply Voltage: 8 to 36 VDC
  • Current Draw: Same as sensor output
  • Warm Up Time: 3 seconds recommended
  • Operating Temperature: -40° to +185°F (-40° to +85°C)
  • Compensation: Uses dynamic temperature compensation 30 to 70°F (-1.1 to 21.1°C). Automatic barometric pressure compensation
  • Weight: 1/2 lb (227 g)


  • Material: 304L Stainless Steel, SS microscreen (hundreds of holes to prevent fouling), electronics are fully encapsulated in marine grade epoxy, guaranteed not to leak
  • Size: up to 13/16 inch diameter x 5 1/2 in long (2 cm dia. x 14 cm long)(small enough for a 1 inch (2.54 cm) well). Titanium option has 1 inch (2.54 cm) diameter.

Vented Cable

  • Conductors: 4 each 22 AWG
  • Material: Marine grade polyether jacket, polyethylene vent tube, full foil shield
  • Outer Diameter: 0.306 inch (0.78 cm)
  • Temperature Range: -22° to +185°F (-30° to +85°C)
  • Weight: 0.7 oz/ft (~65g/m)
  • Length: Standard 25 ft (7.62 m) (up to 500 ft (152.4 m) from factory)

The submersible pressure sensor may be placed slightly below the lowest expected water level. Water level sensor level ranges of 0-3, 0-15, 0-30, 0-60, 0-120, 0-250 and 0-500 ft are available. When ordering, select the level sensor range that will cover the maximum water level change (this is not necessarily the total depth of water). Selecting the smallest water level range possible will ensure the greatest accuracy.

The 4-20 mA signal can run up to 3,000 ft from the water level sensor to the logging device. Common twisted pair or electrical extension cord wire may be spliced to the vented cable once the cable is out of the water. The 4-20 mA signal may be converted to 0.5 to 2.5 VDC by dropping the current signal across a 125 ohm resistor.

The WL400 Water Level Sensor can be used to measure water level, well depth, groundwater level, surface water flow, pipe flow, and water pressure, etc... NOTE: Polyurethane cable is not recomended for use with hydrocarbons or high concentrations of chlorine. Please look at the our WL450 Water Level Transmitter to meet the requirements of these types of applications.

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