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Water Level Transmitters with 4-20mA Output

4-20mA water level transmitters using two-wire loop power. Ideal for wells, tanks, rivers & reservoirs with excellent noise immunity & long cable runs. Designed for reliable integration with PLCs & SCADA in water management applications.

Water level transmitters equipped with a 4-20mA current loop output provide a dependable solution for integrating level measurements into industrial control and monitoring systems. These devices commonly utilize submersible hydrostatic pressure sensors and feature a two-wire design that simplifies installation by transmitting power and signal over the same pair of wires, offering excellent noise immunity crucial for long-distance transmission from locations like boreholes, rivers, reservoirs, and storage tanks. Understanding the specific design features, such as vented gauge pressure reference and material compatibility, is key to selecting the appropriate transmitter for reliable performance in diverse water level applications.

Find out more about Water Level Transmitters with 4-20mA Output to determine which product options and capabilities will best meet your application requirements.

Water level transmitters utilising the industry-standard 4 to 20 milliamp (4-20mA) current loop output offer a robust and reliable method for level measurement in various water-based applications. This two-wire configuration is particularly advantageous, allowing both the power required to operate the transmitter and the analogue level signal to be carried over the same pair of conductors. This significantly simplifies wiring installation and reduces costs, especially over the long cable runs often encountered in borehole, reservoir, or extensive facility monitoring.

The inherent nature of the 4-20mA signal provides excellent noise immunity compared to voltage signals, making it ideal for environments with potential electromagnetic interference often found in industrial settings or near pumps and motors. The ‘live zero’ represented by the 4mA signal allows monitoring systems (like PLCs, SCADA, or dedicated controllers) to easily distinguish between a genuine zero-level reading (4mA) and a fault condition, such as a broken wire or transmitter failure (which would result in 0mA).

These transmitters typically employ a submersible hydrostatic pressure sensor design. The sensor, housed within a rugged, sealed enclosure (often stainless steel grades like 316L for corrosion resistance), measures the pressure exerted by the column of water directly above it. This pressure reading is directly proportional to the water level. Accurate measurement relies on referencing the hydrostatic pressure to the local atmospheric pressure; this is achieved using a vented cable that incorporates a small breathing tube running alongside the electrical conductors, terminating in a protected, breathable location, usually at the instrumentation end. This vented gauge pressure measurement automatically compensates for barometric pressure fluctuations, ensuring true level readings.

Specific construction details are crucial depending on the application. For instance, monitoring levels in deep groundwater wells or boreholes necessitates transmitters with durable, abrasion-resistant cable jacketing (like PUR) and potentially narrower body diameters. Measuring levels in potable water storage tanks requires materials certified for drinking water contact (e.g., specific stainless steel grades, PE or FEP cables). River and reservoir level monitoring often demands robust designs capable of handling potential debris, sediment, and outdoor environmental exposure, typically requiring a high IP rating like IP68 for continuous submersion.

Integration into process control systems is straightforward due to the widespread compatibility of the 4-20mA signal. These transmitters are commonly connected to input modules on PLCs, dedicated digital panel meters for local display, data loggers for environmental monitoring, or telemetry systems for remote water resource management. The signal can represent the full calibrated range of the transmitter, allowing precise tracking of water levels within tanks for process control, monitoring resources in reservoirs for water management, or triggering alarms in flood monitoring systems. For applications in hazardous areas, such as certain wastewater tanks or industrial sumps, intrinsically safe (Ex ia) versions are available which limit the electrical energy to prevent ignition in potentially explosive atmospheres.

Product Help

Specifying water level transmitter with 4-20mA output requirements

Some questions to ask when defining the product requirements for a water level transmitter with 4-20mA output.

Installation type

How do you want to install the water level transmitter, will it be mounted to the outside of a water tank, lowered inside a water tank, or suspended from a platform above the water surface?

Water type

What kind of water will you be measuring, freshwater, seawater, drinking water, chlorinated water or wastewater?

Level range

What range of water level in metres or feet do you need to measure over?

If measuring a water tank, is the tank air tight or vented to outside air pressure?

Accuracy

How accurate does the water level measurement need to be?

Will it be used to determine the quantity of water, or to protect from overfill or underfill?

Electrical connection

Do you have a preference on what type of electrical connector and 4-20mA signal cable to use?

Will the water level transmitter be exposed to an indoor or outdoor environment?

Could the water level transmitter be temporarily flooded or will it be permanent submerged?

If a cable is required, how long does it need to be to connect to the water level measurement instrumentation?

Process connection

If the water level transmitter is going to be external to a tank, how do you intend to mount the sensor if it is going to be fitted to the outside of a tank, what type and size of thread or flange?

Temperature measurement

Would you like to measure the water temperature as well with a separate 4-20mA signal from the same transmitter?

Checklist for water level transmitter with 4-20mA output requirements

Define your water level transmitter with 4-20mA output requirements using this checklist:

  1. Installation type?
  2. Water type?
  3. Level range?
  4. Accuracy?
  5. Electrical connection?
  6. Process connection?
  7. Temperature measurement?