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.
- Hydrostatic Level Sensors
- Water Level Transmitters with 4-20mA Output
- Waste Water Level Sensors
- External Mounted Tank Level Sensors
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.
- 2 metre deep diesel tank level sensor for submersion
- External Mounted Tank Level Sensors
- Aquaculture submersible freshwater level & temperature transmitter
- 0 to 5 volt output sensor for measuring low seawater level
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.
- SDI-12 freshwater submersible pressure sensor for measurement up to 5 metres
- Low power consumption fuel tank level sensor
- 10 metre sea water depth sensor with millivolt output
- Level transmitter for waste water tank 10 feet deep
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
- High temperature water level transmitter for measuring up to 1 mWG
- 10 metre submersible water depth and temperature transducer with USB digital connection
- Water tank level gauge transmitter with adjustable range
- 3 metre range submersible freshwater level transmitter
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Related Technical Terms
- Capacitive Fluid Level Measurement
- cmH2O – Centimetres of Water Column at 4 deg C Pressure Unit
- Conductive Fluid Level Detection
- Float Fluid Level Detection
- ftH2O – Feet of Water Column at 4 deg C Pressure Unit
- mH2O – Metres of Water Gauge at 4 deg C Pressure Unit
- mmH2O – Millimetres of Water Column at 4 deg C Pressure Unit
- Specific Gravity
- Vibrating Tuning Fork Fluid Level Detection
Related Online Tools
- Pressure to Liquid Level Calculator
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- Liquid Level Transmitter 4-20mA Current Output Calculator
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