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Float level sensors are commonly used for various purposes in water tanks, such as filling and draining, as well as for providing an output based on the liquid level in the tank. These water tank float level sensors are available in several types, each of which uses a different principle to measure the liquid level.
These are the most common ones:
Mechanical float switches
These switches are simple and try to perform tasks practically. A floating ball made of a magnetic material such as stainless steel floats the liquid surface. This ball is contained in a housing with two opposing sections of a magnet, known as the reed switch. As the water or any other liquid fills the tank, the float moves up. Then, the magnets inside the float bend the reed switch, causing the switch to change its position. This creates a signal that indicates the tank is full.
Hydrostatic pressure sensors
These sensors measure the pressure at the bottom of a tank to determine how much water is inside. As the water level slightly increases, the pressure it exerts on the bottom balance also increases. This relationship between pressure and water level can be calibrated to derive the water level. These sensors provide a continuous level and are suitable for storage tanks, unlike floating switches that give discrete high and low levels.
Ultrasonic level sensors
Like other level sensors, these are non-intrusive and provide a tank's liquid surface level. They are mounted on top of the tank and emit a high-frequency sound wave, which, depending on the water level, reflects back to the sensor. The time taken for the echo return is measured, and this measurement gives the liquid level. Because ultra sound level sensor works like this, they are not suitable for use with volatile or very noisy liquids.
Capacitance level sensors
These sensors are based on the principle that a liquid changes the capacitance of a probe when it fills up the tank. These sensors can measure conductive liquids by using probes inserted in the tank. Capacitance decreases when the probe is in contact with the liquid and increases when it is in contact with the vapor. The change in capacitance is used to measure the level of liquid in the tank. Capacitance level sensors are relatively complex due to multiple probes for measuring industrial storage tanks.
Automatic operation
Mechanical float level sensors are very easy and effective. The floating object moves with the change in liquid level and sends a signal when the level is too high or low. This makes the sensor useful for automatically filling up or emptying tanks without needing a human to do it. Simple as it looks, the sensors use the float's up and down movement to mechanically switch. This is one of the easiest and most reliable ways of tank monitoring.
Works for many liquids
Water tank float level sensors can monitor almost any liquid, thick or thin. There is even a variant that works for slurries with solid pieces inside. That is due to the different types of floats used. Some are small and can get into tight spaces, while others are big and heavy and can go through anything. A sensor with a damage-proofed float will also work for harsh liquids that could break other floats, like chemicals.
Multiple floats for levels
This is a special feature of some complex level sensors. While most sensors just switch one way at the high and low levels, multi-float sensors switch several times as the level changes. For example, a sensor with three floats could switch at the 25%, 50%, and 75% levels. This would allow the tank to be filled, monitored, and emptied automatically in stages rather than all at once. Multi-float sensors are often used in large tanks where gradual filling and emptying is better than fast fill-ups or drops.
External mounting options
While many floats work by moving through the liquid, some float sensors can be mounted without touching the liquid at all. These sensors use magnets or other methods to detect the float's position from the outside. This makes them good for tanks where opening a small hole is better than large holes. An external float sensor also works best for dangerous liquids that shouldn't be touched.
Resistant to tanks
Most float sensors are tough enough to work for many years, even in hard conditions. Waterproof casings protect parts from water, dirt, and extreme temperatures. Some sensors also stand up to pressure at great depths or blasts from high-pressure water hoses. The float itself is often made of solid plastic or metal that won't wear down or break over time. These durable materials let the sensor keep working with reliable results for a long time - often well over a decade - without needing repairs or replacements.
Liquid properties
To select the correct one, one must consider the kind of liquid in the tank. For example, the sewage lift station float switch can work for almost any liquid. But, some floats are better for chemicals, whereas others should be used in heavier liquids. Go for a float made of strong material, so it doesn't get damaged by anything in the liquid. Also, if the liquid has pressure, find a sensor designed for that.
Tank shape and size
The tank size will also affect the sensor one will choose. Large tanks might need something different than smaller ones. For example, a big tank might need multiple floats so that the level can be accurately checked at different stages. The shape of the tank can pose a problem if the sensor is not suited for it. Consider getting a sensor with a long probe reach if the tank is tall. And for tank with small diameter, choose one with a slim profile.
Installation and maintenance
Next comes the importance of thinking through the installation and maintenance of the chosen sensor. Some of them are easy to set up from the outside without going into the tank. Good selections, especially for big or hard-to-reach tanks. Also, select one that doesn't need much looking after. It's better than one that requires frequent checks, especially if it will be used in a tough place.
Environment
It is also important to think about the environment around the tank. Some of them are designed for harsh outdoor environments. These have special coatings that protect the sensor from dust, rain, or extreme temperatures. One should ensure the sensor is rated for any extreme conditions that could happen in the environment around the water tank.
Output requirements
Lastly, float level sensors come with various output options. Some give simple on/off signals, while others provide precise level measurements. The final decision will depend on the one's needs. If it is required to only know when the tank is too full or too empty, then a simple switch will provide the information. But if a specific level is needed, then pick one that gives a continuous readout of the liquid level.
Water treatment plants
In waste and water treatment plants, reservoirs and surge tanks are commonly used. The float level sensor helps in the reduction of emptying and flooding disasters. Other than that, the sensors assist in the optimization of the plant space by ensuring that the tanks are always at the right level for effective operation.
Pump protection
A float water switch protects pumps from undesirable outcomes, such as dry running and high levels. These situations damage the pump and, therefore, the intense level of float sensors that switches off the pump when the tank is empty or full and turns it back on when the level is optimal again.
Monitor chemical storage
Chemical concentration in water treatment needs to be monitored to avoid problems. The level of the float sensor helps in maintaining the storage tanks at a safe level to minimize the risk of spills and overflows and ensure the chemicals are always available for the processes. This contributes to a safer working place and a reduced risk of environmental contamination.
Industrial boiler
In industrial waste, high-pressure boilers and steam generation will feature float sensors that help to maintain water levels that are critical for safety and operational efficiency. This helps prevent both low water levels, which can lead to cavitation, and high water levels, which can cause dilution. In such a case, the float sensors shut off the heating elements and the float sensors that help maintain the integrity of the boiler system and prevent disasters.
Waste containment ponds
In industries such as mining or oil and gas, wastewater pump and treatment facilities incorporate float level sensors in waste containment ponds or evaporation lagoons for proper management and monitoring of environmental risks. Float sensors in this application assist in the prevention of overflows that potentially endanger ecological balance by releasing hazardous substances into the environment.
Some of the factors that affect the choice of a level sensor for water like sewage float switches are the characteristics of the liquid, environmental conditions, tank shape, size, and chemical composition.
They are manufactured using high-quality materials that offer protection against damage, corrosion, and wear. In addition, the sensors are manufactured with tough and robust materials, including stainless steel and high-density polymers, which are highly resistant to a wide range of chemicals, from extreme temperatures to high-pressure conditions, as well as physical wear and tear. These durable materials ensure that float level switches can withstand harsh industrial conditions for a long time.
Most float level sensors are designed to work with a single liquid. However, there are specific sensors in the market made to accommodate a variety of liquids. Multi-purpose sensors are manufactured using materials that resist all types of potentially damaging elements.
No, level sensors are designed to be maintenance-free, so one does not have to worry about maintaining them. However, in some cases, they may require periodic external cleaning to remove any accumulated debris.
Float level sensors maintain optimal liquid levels in tanks, safeguarding against overflow, dry running, and low liquid levels that can expose dangerous equipment, such as pumps and boilers, to potential hazards. They also monitor high and low levels in hazardous liquid environments, helping to prevent spills and the release of dangerous vapors or gases, which would otherwise be detrimental to the environment and health.
