Ultrasonic Liquid Level Sensors

Ultrasonic echo sounding sensors for measuring liquid level and converting it to an electrical signal to send to other instrumentation.

Ultrasonic liquid level sensors are contactless measurement devices which transmit and receive high frequency acoustic waves to measure the distance to the surface of a liquid based substance.

Featured liquid level measurement products

Water Level Transmitters with 4-20mA Output - Browse for 4-20mA water level transmitters using two-wire loop power. Ideal for wells, tanks, rivers & reservoirs with excellent noise immunity & long cable runs.
LMP307 Submersible Level Transmitter - Submersible level transmitter for measuring liquid level with a 4-20mA current loop or a 0-10V voltage output plus optional ATEX approval for intrinsically safe use in hazardous areas in ranges from 1mH2O up to 250mH2O. The LMP307 is suitable for use on potable water with no leaching, and can be supplied with a drinking water certificate according to DVGW and KTW.

Ultrasonic liquid level sensors are contactless measurement devices which transmit and receive high frequency acoustic waves to measure the distance to the surface of a liquid based substance.

Ultrasound liquid level sensor technology transmits a high frequency sound wave pulse and receives the wave echo reflected off a liquid surface. The time taken for the acoustic pulse to traverse the distance between the transmitter and target surface, and back again to the receiver is measured.

The distance (d) between the ultrasonic liquid level sensor and the liquid surface can be calculated by dividing the time taken (t) by two, and multiplying that by the speed of sound (c) in air, i.e. d = c ∙ t / 2. The liquid level in a tank (LT) can then be determined by subtracting distance (d) from the height of the ultrasonic level sensor (HT), i.e. LT = HT – d.

The performance of a ultrasonic level sensor is mainly affected by changes in the speed of sound and disturbances on or above the surface of the liquid.

The speed of sound will change if the air density changes. Since air density changes in the Earth’s atmosphere are directly related to changes in air temperature (measured in Kelvins), an ultrasonic fluid level sensor is compensated by incorporating an air temperature sensor.

Featured liquid level measurement products

S12C SDI-12 Seawater Pressure & Temperature Transducer - SDI-12 protocol transducer for sensing water depth level and temperature in seawater, brackish water, tidal water, saline water or leachate.
Sonde OEM water depth sensor for 300m deep borehole - We are looking to integrate a pressure sensor into the bottom of a Sonde. The sensor will be used to monitor the water depth in a borehole up to a maximum of 300m.

Surface effects can be reduced by experimenting with the position of the device, installing within a stilling well or wave guide, and some ultrasonic devices include features to minimise the effects of foaming, bubbles, vapour and turbulence.

Since there is no contact with the fluid to be measured, ultrasound liquid level measurement technology can be used in applications where sensors requiring contact are otherwise prohibited. These sensors have no moving parts which makes them very reliable, requiring very little maintenance.

Ultrasonic liquid level sensors are typically housed in a single assembly combining the acoustic transmitter and receiver in one device.

An ultrasonic liquid level sensor is an instrument for measuring the height of a liquid and converting it to an electrical signal. The liquid level signal output can then be utilised by other instrumentation to display, monitor, log or control the liquid level.

Since ultrasonic liquid level sensors are contactless, they are mounted above the surface of the liquid in the top of a tank or from a platform spanning the top of an open tank.

Featured liquid level measurement products

Long range wireless hydrology sensor network for remote water level data acquisition - Monitor river water levels in remote locations using battery-powered wireless transmitters that provide an internal boost circuit for radar sensor loop power.
ATEX Approved Liquid Level Sensors for Hazardous Areas - European hazardous area ATEX approved sensors for liquid level measurement in intrinsically safe installations on petrochemical, pharmaceutical, landfill and sewage treatment sites.

Advantages

No media contact for vertically mounted type, so flexibility for use on different corrosive media, thick fluids, slurries, wastewater
High temperature fluid compatibility for vertically mounted types, since no sensitive components make contact with the fluid
High accuracy due to high frequency pulse wave and precise transit time time measurement
Operates with conductive or non-conductive fluids
Sealed pressurised vessel will not affect performance
Shorter blocking distance than radar

Disadvantages

Foaming, splashing, vapour and humidity can affect measurement performance
High cost compared to other technologies
Top mounting only
Minimal blocking distance limits operation when in proximity to liquid level
Temperature compensation required to compensate for speed of sound variation with air temperature
Sound waves cannot be transmitted through a vacuum
Shorter range than radar

Featured liquid level measurement products

Hydrostatic Level Sensors - Hydrostatic pressure sensing devices for measuring liquid level and converting it to an electrical signal to send to other instrumentation.
S12S SDI-12 Coms IP68 Pressure and Temperature Sensor - Combined pressure and temperature sensor with a 1200 baud rate serial data interface as defined by the SDI-12 support group.