Float actuated devices for monitoring liquid level and activating switch contacts at predetermined liquid level thresholds.
A float liquid level switch is an instrument for monitoring the height of a liquid and tripping an electrical contact switch 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
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
External Mounted Tank Level Sensors - External mounted level sensors for installing on the outside of a liquid storage tank to measure level of tank contents.
Float liquid level switches are threshold contact trip devices which typically consist of a buoyancy component which is typically a sealed hollow ball or cylinder which will float on a liquid, and either a shaft assembly for vertical mounting, or a hinge mechanism for horizontal mounting.
As the level increases and decreases a float will be pushed up or drop down. The float can be connected to a hinge that opens and closes or slides along a shaft.
The position of the float along the shaft or the opening and closing of the hinge can be detected by various means.
A vertical mount sliding float type level switch will have a permanent magnet incorporated into the float which slides up and down the shaft. A magnetic reed switch is positioned along the shaft to the required level set point. When the float passes over the reed switch it will open or close the level switch circuit.
A horizontal mount hinged type float level switch will incorporate either a microswitch or a magnetic reed switch, which is activated by an actuator or lever connected to the float.
Featured liquid level measurement products
IMCL Low Cost Submersible Pressure Sensor - Economical IP68 protected sensor with stainless steel 316L housing and Ceramic strain gauge sensing diaphragm for measuring liquid depth pressure.- IMSTL IP68 Water Temperature and Depth Transmitter - Stainless steel 316L waterproof probe for measuring both water temperature and depth and generating two separate 4-20mA current loop measurement signals.
It is possible to fit more than one switch to shaft type float switch, and provide liquid level control for a number of separate processes which are activated at different levels.
A float level switch makes direct contact with the liquid to be measured, and therefore material compatibility must be considered.
Since there are no pressure sensitive components exposed to the inside of the tank it is possible to fit float level switches to sealed pressurised tanks.
Float liquid level switches can be designed to mount through the top, side or bottom of a tank. Side entry type float level switches have hinged floats, and top and bottom entry type float level switches have sliding floats.
Featured liquid level measurement products
- Low power consumption SDI-12 lake water level sensor - Monitor lake water levels accurately with this low power SDI-12 sensor. Features durable PUR cable and PC logging software for easy data analysis.
Storm surge protected low range submersible river level transmitter - This submersible level transmitter offers accurate low range water level monitoring with high overpressure resistance for storm surge protection in rivers
Advantages
- Different types available for top, side or bottom entry mounting
- Cheapest type of liquid level switch
- Simple design and construction
- Not sensitive to changes in SG & density
- Some types do not require power to operate
- Surface disturbances such as ripples, foaming and bubbling will not affect performance
- Dielectric constant or conductivity of fluid will not affect operation
- Different materials for media compatibility can be specified
- Vapours, condensation and mists will not affect operation
- Vacuum and low pressure sealed tank will not compromise buoyancy of float
Disadvantages
- Moving parts vulnerable to clogging, wear and tear, and damage
- Fouling can cause unreliable movement or seizure of float actuation
- Float actuation relies on liquid contact
- Turbulence in the fluid may cause the float to move
- Thick or sticky fluids may prevent the float from moving
- Regular maintenance to ensure nothing is restricting float movement
- Single point level switch with side entry type
- Float assembly protruding into liquid causing obstruction, attracting fouling and hygienic cleanliness issues
Featured liquid level measurement products
- External Mounted Tank Level Sensors - External mounted level sensors for installing on the outside of a liquid storage tank to measure level of tank contents.
LMK 858 Plastic Submersible Liquid Level Sensor with Removable Cable - Chemical resistant liquid level sensor with detachable signal cable for measuring quantity of aggressive media such acids and alkalis and sludge in tanks located outside of factory buildings.
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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
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