Level sensors, alternatively called float switches, are instruments employed for determining the liquid level in a vessel. Their functionality involves the use of a buoyant object, known as a float, that is fastened to a switch or sensor to measure the liquid level.
How does a float switch work?
A float switch works by using a buoyant object, called a float, which is attached to a switch or sensor. A water tank, or similar liquid-containing vessel, is where the float is situated.
When the liquid level fluctuates, the float moves correspondingly, either up or down. This movement activates a switch or sensor attached to the float, which then triggers when the float reaches a predetermined level.
This can activate or deactivate a pump, for example, to keep the water level within a specific range. The switch or sensor can be of different types, including mechanical switches, reed switches, and magnetic switches, each with its own mechanism of operation.
Some float switches also use an external counterweight to improve accuracy and stability.
Switching method
There are several different methods of switching used in float switches. These include:
Mechanical switches:
This type of switch uses a lever and a switch contact to make or break an electrical circuit. When the float reaches a certain level, it activates the lever, which in turn triggers the switch contact to open or close the circuit.
Reed switches:
Reed switches use a small glass tube filled with a metal vapor that conducts electricity when it is near a magnet. When the float reaches a certain level, it activates the magnet, which in turn triggers the reed switch to open or close the circuit.
Magnetic switches:
Magnetic switches use a magnet that is attached to the float, which triggers a switch when it comes into contact with a magnetic sensor. These switches can be used to detect a specific level or multiple levels of liquid.
Mechanical switches use a lever and a switch contact to make or break an electrical circuit. Reed switches use a small glass tube filled with a metal vapor that conducts electricity when it is near a magnet. Magnetic switches use a magnet that is attached to the float, which triggers a switch when it comes into contact with a magnetic sensor.
External counterweight
An external counterweight can be used to improve the accuracy of a float switch. The counterweight is placed on the opposite side of the float from the switch, and it helps to balance the float so that it is more stable and less likely to be affected by external factors such as waves or currents.
Float switch wiring
The wiring is usually very simple and straightforward. The float switch has two wires, one for the power supply and the other for the output signal. These wires are connected to the control panel or pump using electrical connectors.
The wiring diagram provided by the manufacturer should be followed for proper installation. The wiring diagram will indicate which wire is for the power supply and which wire is for the output signal. It will also indicate the voltage and amperage requirements for the float switch.
It is important to use the correct gauge wire for the voltage and amperage requirements of the float switch to ensure proper operation and prevent damage to the float switch or other equipment.
The wire should also be rated for the environment in which the float switch will be installed.
It's also important to use proper electrical techniques when wiring the float switch, such as using wire nuts, and electrical tape, and properly grounding the float switch.
The float switch should be tested after installation to ensure that it is functioning properly and that it is wired correctly.
Float switch materials
Several different materials can be used to make float switches, including plastic and stainless steel.
Plastic float switch Plastic float switches are lightweight, durable, and inexpensive. They are often used in small water tanks or in applications where the liquid is not corrosive.
Stainless steel float switch Stainless steel float switches are more heavy-duty and are often used in larger water tanks or in applications where the liquid is corrosive.
They are more expensive than plastic float switches, but they are also more durable and have a longer lifespan.
Float switch standards
UL standard: Float switches are evaluated using a variety of tests, including immersion tests, dielectric voltage-withstand tests, tensile strength, ultimate elongation tests, and insulation resistance tests. These tests are all included in UL's Standard for Industrial Control Equipment.
CE standard: According to TRD 401, 402, or 602, the float switch can be utilized as a water level limiter for steam generators. The item complies with EU 2014/68/EU module B and bears the notified body's CE mark no. 0035. standards according to EN 13445, EN 12952, EN 12953, AD 2000, or ASME-Boiler were used.
Types of float switches
There are several types of float switches available, each with its own unique features and capabilities. Some of the most common types include:
Stem-Mounted Float Switches:
Float switches that are installed on stems can only move a float up and down a stem and only control one float at a time.
Stem-mounted float switches can range in complexity from straightforward single-point switches with one float on one stem to intricate multi-point switches with up to seven floats on one stem. The orientation of single-point float switches can be either vertical or horizontal.
Cable-Suspended Float Switches:
Float switches that are hung by wires are completely free to move. A cable-suspended float switch will float along as far as the cable will allow if it is not tethered.
Float and cable-suspended float switches are all mechanically quite comparable, but they can have significantly more varied electrical configurations than stem-mounted float switches.
Vertical float switch:
This type of float switch is designed to be used in a vertical position and can sense the liquid level in a tank or a pipe.
Horizontal float switch:
This type of float switch is designed to be used in a horizontal position and can sense the liquid level in a sump or a tank.
External float switch:
This type of switch is designed to be mounted outside of the tank or container, and it uses a cable to connect to the switch inside. 
Applications
Float switches are used in a wide range of applications, including water tanks, sump pumps, and irrigation systems. They are also used in industrial applications such as chemical processing and oil and gas production.
They can be used for controlling the level of a liquid in a tank, activating or deactivating a pump, and as water level sensor float switch, water level float switch, and water float switch. A float switch diagram is often provided by the manufacturer to help with installation and wiring.
Conclusion
Float switches are versatile and useful devices that can be used in a variety of applications. By understanding their design, materials, and standards, as well as the different types of float switches available, you can choose the right one for your needs. If you're looking for high-quality float switches, be sure to check out our Float switches.
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