Liquid level senders, also known as liquid level sending units, are devices that measure the level of liquid in a reservoir or storage tank. These products are used in marine, vehicular, and industrial applications to detect fuel, water, or other solution levels. When choosing a level sender, there are several signal considerations to keep in mind.

Analog Level Senders

Analog liquid level senders include resistive, voltage, and current signals. These products use mechanical parts to display a reading.

Resistive Level Senders

To determine fluid level measurements, resistive fluid level meters use two wires within a storage tank. The liquid level within the tank determines the extent to which the wires are in contact with one another. This determines the total resistance in ohms. The fluid level of the tank can then be deduced depending on the liquid contained within the tank.

Voltage Level Senders

Voltage level sensors measure the voltage across a variable resistor to determine fluid levels within a tank. Most commonly, this system uses a float attached to a rod which is then attached to the variable resistor. Voltage within the system varies depending on the arm position in relation to the resistor. These changes in voltage can then be converted into fluid-level readings.

Current Level Senders

A current level sender is a device that measures electrical current in milliamps. High and low limits of the tank are calculated and converted to a standardized 4-20 mA current output range. Unlike voltage, current does not degrade over long connections, making a 4-20 mA current loop an ideal option for longer travel distances. Additionally, the low-end 4 mA is equivalent to no output, making troubleshooting the system a simpler process.

Digital Level Senders

Digital liquid level senders include products built to J1939, NMEA 2000, RS232, and RS485 digital communications standards. These products use transducers to convert readings into an electrical signal that can then be displayed for an operator.

J1939 Vehicle CAN Bus

The SAE J1939 protocol is a widely used vehicle bus for communications and diagnostics and is used in many vehicles, particularly diesel-powered applications. Vehicles with electronic control units (ECUs) can more easily communicate data between systems using this protocol. The standard is common in land-based vehicles, marine applications, and industrial settings. 

NMEA 2000 Communications Standard

The National Marine Electronics Association (NMEA) developed NMEA 2000, also known as NMEA2K or N2K, to improve communication standards among device manufacturers. The system uses a standard central cable that links connected devices to the primary system.

For a more in-depth look at the NMEA 2000 standard, check out our guide to NMEA 2000.

RS-232 Standard

Recommended Standard 232, abbreviated to RS-232, is a telecommunications standard for serial communication transmission of data. In this system, each bit of data is transmitted individually. In contrast, parallel communication involves several lines of data transmission simultaneously. Though serial communication is slower, it offers a cheaper data transmission solution.

Notably, the RS-232 standard can also be found on older computer peripherals like computer mice, printers, and modems.

RS-485 Standard

Also known as TIA-485(-A) or EIA-485, the RS-485 standard is an electrical interface for use with serial communications systems. This standard is used in installations where electrical noise is common, making the standard particularly useful in industrial applications. 

KUS Delivers High-Quality Level Senders for Manufacturers

As the developer of the world’s first reed switch level sender for marine applications, KUS has been a leader in the industry from the start. OEM manufacturers have come to recognize the quality, reliability, and accuracy of KUS products. If your industry demands level senders built to perform at a high level, KUS has what you need.

If you have any questions about level senders or any of our other products available, our team is here to help. Contact us for more information, and a product specialist will be in touch with you.