Vibrating tuning fork devices for monitoring liquid level and activating switch contacts at predetermined liquid level thresholds.
A vibrating tuning fork liquid level switch is an instrument for monitoring the height of a liquid and tripping a relay contact switch or transmitting a solid state relay switch output when a maximum, minimum or intermediate level has been reached. The liquid level switch output can then be utilised by other instrumentation to open a valve, illuminate a warning lamp, activate an audible alarm, or switch on a pump.
Featured liquid level measurement products
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.
LMK458 Marine Approved Hydrostatic Level Transmitter - Marine approved level transmitter with 4-20mA output for measuring level of contents inside ship ballast, fuel, liquid cargo or wastewater tanks
Vibrating tuning fork liquid level switches are threshold contact trip devices which typically consist of a tuning fork which extends out from the switch housing.
In operation a piezoelectric oscillator is used to vibrate the tuning fork at its natural frequency for air.
A second piezoelectric device is used to pick-up the frequency of the vibrating tuning fork. When the liquid level rises and covers the tuning fork it will vibrate at a lower frequency.
This change in vibration frequency is used to detect when the required liquid level has been reached.
Featured liquid level measurement products
LevCal Submersible Hydrostatic Liquid Level Sensor Calibration Kit - Pressure calibration kit for calibrating a submersible hydrostatic liquid level sensor out of the water using a battery powered automatic pressure controller calibrator to generate and accurate source of air pressure, and the necessary test hose and adapters to attach to the different types and styles of submersible pressure sensor probe ends.
Tank level transmitter monitoring accessible globally via smartphone - Industrial solution for connecting your existing 4-20mA level transmitters to the internet. Enable global monitoring on your smartphone with live data, trends, and SMS alarms.
A vibrating tuning fork liquid level switch makes direct contact with the liquid to be measured, and therefore material compatibility has to be a consideration.
Since there are no pressure sensitive components exposed to the inside of the tank it is possible to fit tuning fork level switches to sealed pressurised tanks.
Also, since there is no sensitive components immersed in the fluid it is possible to use them on higher temperature media that would not be tolerated by other types of liquid level switch.
Vibrating tuning fork liquid level switches are generally mounted through the top or side of the tank with the tuning fork protruding horizontally into the tank.
Featured liquid level measurement products
Submersible water level and temperature probe with SDI-12/USB interface for freshwater monitoring - Versatile 10m water level and temperature probe with USB and SDI-12 connectivity, designed for hydrological studies and long-term environmental monitoring programs.
IP68 sewage level transmitter with 6m/20ft range, ATEX IS approval and FEP cable - Monitor wastewater levels with this robust IP68 submersible sensor featuring a flush ceramic diaphragm and FEP cable. ATEX approved for hazardous areas.
Advantages
- Not affected by any surface disturbances such turbulence, foaming, vibration
- High temperature fluid compatibility since no sensitive components make contact with the fluid
- Small compact size
- Sealed pressurised or evacuated vessels will not affect performance
Disadvantages
- Thick or sticky media will leave a coating on the probe which will affect vibration frequency
- Fouling can interfere with resonant frequency causing false switch activation
- Tuning fork protruding into liquid causing obstruction, attracting fouling and hygienic cleanliness issues
- High cost
Featured liquid level measurement products
LMK382 Low Range IP68 Waste Water Level Transmitter - Submersible Low Range waste water level transmitter with intrinsically safe option for monitoring the level of sewage and effluent in water treatment plants.- IWSL Potable Water Submersible Level Sensor - IP68 protect pressure sensor for monitoring potable water level to depths of 100 metres.
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Related Technical Terms
- Capacitive Fluid Level Measurement
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- mH2O – Metres of Water Gauge at 4 deg C Pressure Unit
- mmH2O – Millimetres of Water Column at 4 deg C Pressure Unit
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