What is the purpose of a float switch and how does it work?

Equipment maintenance and repair

A float-type switch is a structurally simple and affordable device. It functions reliably and efficiently even in an aggressive environment and is not afraid of intense loads. Subject to compliance with the operating rules stated by the manufacturer, it fulfills the entire warranty period and after it also continues to fulfill its duties with high quality.

The presence of a float allows you to control the operation of the pump and program it for the future. For example, a drainage unit can be installed in an area of ​​constant flooding. When the water level reaches a predetermined level, the switch will record this and immediately signal the pump to start pumping

If the module is used only in a complex of structures involved in drainage or water supply, it does not require regular maintenance. The aquatic environment is considered the least problematic and does not have any negative impact on the equipment.

The float switch that controls the operation of the drainage system is subject to heavy loads, as it is constantly located in a liquid medium containing a large amount of impurities, fragments of fine gravel, sand and organic residues

If the field of activity of the float is located in more aggressive, difficult conditions, for example, in sewer or fecal pits, the device requires more serious attention. Plumbers recommend thoroughly rinsing the float with a hose at least once a month to prevent it from sticking to the pressure pipe or pump walls during daily operation.

If the equipment is regularly rinsed with running water, it will last much longer and will not lose its functionality even over time.

Plumbers recommend thoroughly rinsing the float with a hose at least once a month to prevent it from sticking to the pressure pipe or pump walls during daily operation. If the equipment is regularly rinsed with a stream of water, it will last much longer and will not lose its functionality even over time.

The most common breakdowns of the unit include burnout of contacts in the electrical cable, damage to the insulating layer, violation of the seal of the housing and penetration of moisture into it. If such problems occur, all faulty elements must be replaced immediately, since they cannot be repaired.

The internal structure of the float controller is not difficult at all. The device, as a rule, is reliable, works for a long time and does not cause any trouble to its owners.

If the electronic module itself fails, the owners will have to throw it away and install a new one in the tank as quickly as possible. It’s not worth buying the first float element you come across, even if its price is attractive.

It is better to contact a specialized service center and purchase a branded certified part with documents that fully meets all the requirements for equipment of this type.

Float device

All units that are equipped with a float switch operate in automatic mode. This eliminates constant monitoring of the level of contaminated liquid, preventing the container from overflowing. In this case, the equipment will not work idle. When the liquid reaches the highest set level, the pump automatically turns on. Once the water level drops to the minimum level, the device will automatically turn off.

It is better to set the minimum shutdown level above the 0.5 cm mark. This will avoid overheating of the equipment in the future in the event of an emergency. In this case, none of the elements will fail in the event of deviation from operating requirements.

The sensor itself can be:

• installed separately (in most cases);
• located inside the case (works on the basis of a sensor).

The floats located outside the housing are made of special plastic, which has a small metal ball and a switch inside, which is connected directly to the network. Depending on the liquid level, the internal contacts are closed using the same ball. Opening follows the same principle. But the electrical type switch can be located outside the housing. A cable or cord will be used to connect to the device. Automatic floats are:

• heavy;
• lungs.

Depending on the device model, the cord length can range from 2 to 10 m. In most cases, submersible models are equipped with built-in sensors. Such devices are much more convenient to operate. In this case, the element located on the body will not be able to catch and be damaged by any protrusions or stones located in the container. However, such devices with built-in floats are used only for pumping clean liquid.

Its main functions are:

• device management;
• automated level sensor (level control).

Features of making the right purchase

Before purchasing a float alarm, you should clearly define the scope and method of its use, as well as determine the necessary electrical characteristics, the dimensions of the device itself and the length of the wire. If the float is needed for drainage or water intake needs, then it will be quite possible to get by with a lightweight budget model. It has the necessary buoyancy, clearly responds to the level of input in the controlled container and immediately transmits a signal to other parts of the system involved in the process if any changes occur. But for drainage and fecal systems, special heavy and expensive modules will be needed (sometimes they are not even equipped with weights), because their design involves close interaction with an aggressive environment. It is worth noting that it is not worth purchasing them for clean water, because their output will be equal to light ones, but the price is orders of magnitude higher.

Some nuances of electrical characteristics

The voltage and current of the float unit must clearly correlate with the same parameters of the pumping equipment used. The voltage is usually 220 Volts, fluctuations in this indicator are permissible from 5 to 10 percent (in both directions). However, the current strength of the switch unit must exceed the limits required for the pump. Instructions for floats often indicate active/reactive load. Accordingly, when connecting it to a pump, this position must be taken into account according to the reactive indicator.

The operating temperature of float devices is quite high - so there is absolutely no need to worry about this. Another thing is the length of the outgoing connection cable - standardly it has a length of 2 to 10 meters. Devices with a short cable length are suitable for household containers of shallow depth, and long cables are useful for working in water utility tanks or deep wells or wells.

WWQ FS

​Photo: https://beru.ru

A universal device that can be installed for any purpose. The device has a durable plastic case and a long cable. The maximum load is 4 kW, while the rated current is 4 A. The tightness is at the highest level, so neither dust particles nor water will penetrate inside the product, which ensures high durability and trouble-free operation.

Float switch WWQ FS

Advantages:

• low cost
• durability
• robust housing
• easy installation

Flaws:

• not detected

Floats on mounting rod

One tank can contain up to several switches, each of which has its own function: one controls the auxiliary pump, another controls the main pump, the third acts as an emergency water level sensor, and the fourth monitors overflow. In any case, the number of floats is determined by the number of connected pumps, as well as the need for protective devices in the system. Several floats are mounted on a special mounting rod. In its role, you can successfully use a plastic pipe securely fixed in the tank. The float switches are fixed on the rod at a distance from each other so as not to interfere with the work of the neighbor. The cable of each switch is secured using clamps. There are situations when necessity dictates the use of several rods at once for attaching floats. Taking into account operating conditions and project features, the number of float switches required to organize the work of a particular system is determined.

There are two types of float switches:

• Lightweight - for a system that controls water supply or water disposal;
• Heavy - designed to control drainage or sewage pumps.

What is important to know about installation?

Depending on the intended purpose, the installation method may vary. However, before installing the device, you should know that operation is not allowed only when the rated current value is several times higher than the maximum. The parameter is indicated on the box and in the technical notes. device passport. The easiest way to place the switch is to place it in a tank. To do this, you need to equip it with a special weight and make sure that the design is designed for such use.

The sinker must be fixed to the cable; often this element is included in the kit, so there is no need to look for available materials. After fixing, you should calculate the free play; it is recommended to do this in a practical way, so the readings will be more accurate. Once the user has completed the calculations, it is necessary to install the cable on the outside of the container. The last point is connection to pumping equipment.

There is another method that is often used in the household - using a supply cable. This option is easy and does not require any calculations; the only thing to remember is that there should be no other sensors or elements inside the tank that the equipment can get caught on.

In some cases it is necessary to install multiple float switches. Each device is fixed on a special rod made of plastic and installed inside the container. Floats must not only be installed, but also be properly adjusted and well placed on the structure. The accuracy of the work depends on this. The wires that come from the switch body are fixed using ordinary clamps. The number of sensors directly depends on the number of installed pumps.

Correct operation and maintenance

Compliance with basic recommendations for use ensures a long service life of each device. The switch does not require maintenance only when it is placed in water supply systems. But when the product operates in the sewer, it must be inspected and cleaned at least once a month. To do this, use a strong jet of water, which will instantly remove any dirt that has formed.

This is an important step as it prevents the float from sticking. If the device is broken, it is more advisable to buy a new one or replace it at a service center

Carrying out repairs yourself without special equipment is prohibited. Because the seal of the housing is broken.

The device operates properly at temperatures of 0...60 degrees. There are some manufacturers that produce designs that can withstand up to 70°, which allows you to expand the scope of application of the switches.

The length of the cable is important because it determines where the product will be used. If a person buys a 2-meter version, then it is recommended to use it only in small tanks. For wells and some storage tanks, you should purchase products with a wire length of 5-6 meters.

Marco AS2

​Photo: https://beru.ru

A good product made in Italy, which has a high service life and reliability. The main advantage of the device is the ability to control a small water level (from 20 to 50 mm). This is not found in every design, which makes the product unique. The body is smooth and has no irregularities, which allows it to be used in any system. The outer part is made of impact-resistant plastic, which is also a good solution. Operating current – ​​10 A.

Float switch Marco AS2

Advantages:

• efficiency
• durability
• stylish appearance
• wide range of applications

Flaws:

• not detected

Purpose

Almost every pump is equipped with special devices that monitor correct operation and prevent malfunctions. One of the popular and effective means of control is a float switch. The main feature of the product is its functionality and practicality. It can work not as an actuator, but also as a water level sensor, and can be placed in any container.

One container can contain up to 3-4 float switches, and they will solve certain problems:

• Monitor the correct operation of the main pump;
• Turn off equipment in an emergency;
• Contribute to the operation of the auxiliary pump;
• Completely replace some sensors to save space.

With such a product, the pump will always be protected from “dry running”, which will prevent rapid wear and tear. Additionally, if a person is filling a large tank, the switch is able to monitor the water level and prevent overflow. The equipment is sold in two versions: heavy and light. The first is recommended for installation in drainage or rainwater drains, and the second is suitable for standard work with clean water. The cable length is different for everyone, the minimum value is 2 meters.

Advantages of the equipment

One of the main advantages of this device is the ability to function as a standard water level sensor. The product performs this function regardless of its main purpose. Thanks to this solution, it is easier for a person to use an electric pump, in addition, the product simplifies the control of some water supply systems.

The second feature of the device is the ability to function as part of the main equipment when constructing sewer systems. Due to its simple design and high efficiency, the product is in high demand in areas where it is necessary to constantly monitor the liquid level. This not only prevents the electric pump from running dry, but also prevents the water level from rising.

Purpose and features

Most country houses are equipped with autonomous water supply systems. The main working elements of these systems are household drainage pumps. The durability of the entire building depends on the efficiency of their work.

Using a pump designed for drainage, you can implement a number of tasks:

• pumping out water from flooded areas that appears as a result of heavy rainfall, melting snow or rising groundwater levels;
• pumping water from trenches and pits created during construction;
• drainage of low-lying areas;
• for dirty water that is pumped out of cellars and basements;
• cleaning wells from deposits on the walls of the shafts and in the bottom;
• transfer of dirty liquid medium between modules of local treatment structures;
• pumping liquid from a natural reservoir for its further use as watering for plants.

The scope of operation of pumps is huge, which makes them popular among owners of country houses and dachas. All equipment, regardless of type, has a similar design. The main components include the rotor, discharge chamber, impeller, motor stator and float switch. The efficiency and durability of the tool, as a rule, depends on the quality of the seals designed to seal the electric motor from waste water. In expensive models they are made from ceramics. The body is made of stainless steel or cast iron, which are resistant to corrosion and mechanical stress.

The pump is controlled by a float switch, which automatically turns the drive on and off. This element is a plastic box, inside of which there is a steel ball and an electrical switch.

The essence of the operation of the drainage pump is that the liquid that is pumped out is poured into a functioning chamber, where, under the influence of the pump and the rotation of the running wheel, it moves upward - towards the outlet pipeline, cooling the drive.

The role of alarms in drainage pumps

A drainage pump with a float switch is widely used both in industry and in everyday life. Its scope of use is cleaning wells, removing dirty liquid, etc. In a drainage pump, the float is equipped with the function of turning the drive on and off automatically. The switch is lowered into the wastewater via an extended cable along with a pipe for collecting liquid. The vertical type drain pump kit includes a vertical float switch with the function of pumping liquid out of a confined space. Such a drainage pump can, for example, drain inactive pipelines.

Types of fill level monitoring products

Liquid level monitoring devices are divided into two main types: contact and non-contact.

Proximity sensors: description

They are used mainly in industrial processes and are divided into ultrasonic devices, capacitive, electrode, working on the hydrostatic principle, and so on. Such devices are used not only in water, but also in other environments, including aggressive ones. The circuit includes, in addition to the sensor itself, which is immersed or installed on the walls of the tank, a control controller, which is installed in a separate control unit outside the tank. Such systems are complex and expensive, and, therefore, unprofitable for use in domestic conditions.

To control the filling level of the tank with water necessary for irrigation or plumbing, it is more advisable to use simpler and cheaper devices.

Characteristics of contact devices

The most common devices for monitoring the filling of tanks in this type are float-type contact sensors assembled on the basis of reed switches. The devices are simple, reliable and cheap. They are divided according to their location in a container with liquid:

1. Vertical arrangement. A rod with a float and a magnet moves along a vertical tube on which the reed switches for turning the pump on and off are located.
2. Horizontal placement. Installed in the upper or lower part of the tank wall. As the tank is filled, the float with a magnet attached to it rises on a transverse rod to the reed switch, which switches off the power supply to the pump.

Float sensors for filling control with various design features can be purchased in stores. The choice depends on the specific installation location of the device and operating conditions.

Selection rules

When purchasing a liquid level sensor in a tank, you need to take into account several factors; if they are observed, the device will work correctly and reliably. First of all, you need to determine the type of liquid medium and its density, the level of danger to humans. What matters is the material used to make the container and its volume—the operating principle of the selected sensor depends on these parameters.

The next point that you need to pay attention to is the purpose of the device; it will be used to control the minimum and maximum liquid levels or to constantly monitor the filling of the tank. When choosing industrial sensors, the number of criteria can be expanded; for household alarms and level meters, it is enough to take into account the volume of the tank and the type of device

At home, home-made devices are used - they work no worse than factory models

When choosing industrial sensors, the number of criteria can be expanded; for household alarms and level meters, it is enough to take into account the volume of the tank and the type of device. At home, home-made devices are used - they work no worse than factory models.

Operating principle of float switches

There are a huge variety of ways to operate float switches for water tanks, which is dictated by the variety of their designs. There are several classic options when:

• the switch blocks the electric motor of the pump when it floats to the surface of the container when it is filled, and resumes its operation again when the tank is empty;
• a water level float switch for the pump starts the automatic water pump when the tank is filled and turns it off when it runs out of water;
• a float that floats to the top of the tank sends a signal to close the valve or servomotor and, once at the bottom of the tank, opens them again;
• the switch signals to the operator or dispatcher that the hydraulic accumulator is full (at the moment when it is at the required level) or about a lack of liquid when it sinks to the bottom in an empty tank;
• a float installed in a sewer pit turns on a fecal pump for distilling waste water when it is filled. When the sump is empty, the float turns off the pump until the next time;
• a two-level switch is designed for two pumps at once - one of them pumps water when the float takes its lower position, and the other - in its upper position. Moreover, when one pump is running, the second is inactive.

How to connect a float switch to a pump?

Manufacturers of floats provide several methods for installing and connecting devices. In any case, before installing a float for the pump, you will need to make sure that the current consumed by the equipment is less than the maximum permissible specified in the operating instructions for the unit.

The easiest way is to install the float in a special container. To do this, use the cable and sinker supplied with the device. To install the float, you must:

1. Place a sinker on the existing cable and calculate the free play of the switch;
2. Attach the sinker using the latch;
3. Carefully secure the cable outside the container.

After installation, the float switch must be connected to the pump. To do this, you need to use the circuit, which, as a rule, comes complete with the device.

Next, you need to check the functionality of the system. The user must turn on the unit and wait about 2 hours. The equipment must pump out water consistently. If it malfunctions, you need to turn off the pump and check that the switch is installed correctly.

Design and principle of operation of the switch

Float design: electric switch and steel ball placed in the internal cavity of a plastic housing. The cable length varies from 3 to 10 m. When the float switch reaches the upper mark, the switch contacts close, turning on the pump. As soon as the float descends to the lower mark, the steel ball acts on the switch lever, changing its location. The circuit opens and the system turns off.

Float switch connection diagram: a cable with three wires is connected to the switch. They vary in color, often being black, blue and brown. The common wire is marked in black.

In the upper location of the float switch, the contacts of the common wire and the normally closed wire, indicated in brown, are closed. At the minimum mark, the circuit is closed with the participation of a common wire and a normally open wire, indicated in blue. The insulation of wires not currently used in the circuit must be very reliable. It is understood that in an aquatic environment the cable must have sufficient moisture resistance, and the plastic case must be leak-tight. The cable outlet is equipped to relieve mechanical stress and is reliably sealed. The polymer resin filling the cavity of the cable glands prevents moisture from getting inside. And the last word in favor of the float switch is the price, which usually varies from 300 to 500 rubles. The combination of a reasonable price and reliability makes the purchase of a float switch the best option for providing protection against unwanted breakdowns of expensive equipment, such as household and industrial pumps.

DIY float sensor

Making float water level detectors yourself is quite simple. First of all, you need to prepare a small diameter tube. Then a head is selected for it. In this case, the seal should be of small thickness. The most common choice is plastic rings. Then, to make a level device (float) with your own hands, you need to secure an insulating plate in the tube. The cable entry is connected last. It is more expedient to determine the counteraction contacts in the upper part of the device. To improve the sealing of the model, a rubber plug is perfect.

Self-manufacturing of the sensor

Suppose the task is to automate the use of a “Malysh” type pump to provide water to a summer house or country house. As a rule, water is pumped into a storage tank, and it is necessary to ensure timely, automatic shutdown of the pump when the tank is sufficiently filled. There is no need to install complex and expensive sensors for this. You can make a device based on a reed switch that will perfectly perform the task with your own hands. Let's call this device: an electric float valve for the water level in a tank based on a reed switch.

Reed switch

A reed switch is a switch that is the main performing part in the device of a reed switch water level sensor for controlling a pump. It looks like a small sealed glass container with a vacuum or inert gas inside. Inside there is a closed or open contact group, in other words, two closed or open contacts made of ferromagnetic material with a gold or silver top coating. When exposed to a magnetic field, the contacts of the part are magnetized and repel each other, opening the circuit in which they are connected, stopping its operation, or, conversely, they close and turn on the circuit. Reed switches are divided into two types:

• Reed switch with normally closed contacts.
• Reed switch with normally open contacts.

The environment inside the glass bulb prevents oxidation of contacts and the formation of sparks when shorted.

Sensor device based on a reed switch

To manufacture the device, you will need a 220-volt magnetic coil starter and a pair of reed switches, one of which is closed in the normal state, and the second is open. And you will also need a float for the water tank, which is made of foam plastic, a rod, a tube and three wires of small cross-section and thickness.

The operation of the device is simple and, most importantly, safe. The operating principle is as follows:

• In the process of collecting liquid, the float with a magnet, having reached the maximum level of the reed switch, which is in a closed state, opens under the influence of the magnetic field, commutating the power triggering coil, which turns off the pump.
• As the water from the reservoir decreases, the float lowers and when it reaches the lower reed switch, which is triggered by a short circuit under the influence of a magnetic field, the starting coil is switched to start the pump.
• A sensor made according to this principle can operate for many years without complaints, unlike electronic control systems for monitoring the filling of containers. Making a float water level sensor with your own hands is not difficult, and it does not require any special knowledge in the field of electrical engineering.

Scheme for controlling water pumping by a drainage pump

Based on the principle of vertical operation of the float mechanism, it is possible to propose a sensor connection diagram for switching the drain pump start relay with an additional 12 volt power supply.

It is worth noting that reed switches are not capable of handling high currents and cannot turn the pump on or off directly. Therefore, they are used in low voltage circuits to switch high-power relays to start or stop a pump. When the level is high, liquid is pumped out until the minimum set level is reached. The operating principle is as follows:

• When the liquid in the container rises to the upper level, the float with a magnet closes the upper reed switch SV 1, and current begins to flow to the relay coil P1. The contacts close in parallel with the connected reed switch, which puts the relay into a self-capturing state. This function does not allow the coil supply voltage to be switched off when the reed switch SV 1 is opened. This is achieved by connecting the relay load and its coil in one circuit.
• The power coil of relay P2 in the electric pump power circuit is switched on and liquid pumping begins.
• When the liquid level decreases, the float with a magnet reaches the lower reed switch SV 2, closing its contacts. A positive voltage potential begins to be supplied to the relay coil P1 from the other side as well. This leads to the removal of the self-capture function and the relay being turned off, which switches off the power coil P2, which provides power to the electric pump.
• By swapping the reed switches SV 1 and SV 2, the sensor will turn off the pump when the container is filled to the set level and turn it on when the liquid level drops.

GILEKS 9008 1 m

​Photo: https://beru.ru

Float switch - universal Gilex 9008 is used to adjust the operation of the pump, connect and disconnect the power line contacts. The switch allows you to control the water level in the water supply system. Using the device, you can prevent dry running in the absence of water necessary for stable operation of the pump, as well as to turn on the device when the required amount is present.

Float switch GILEKS 9008 1 m

Advantages:

• efficiency
• nice price
• versatility

Flaws:

• not detected

The float switch is one of the main elements, so special attention must be paid to its selection. Because the correct operation of pumping equipment depends on the quality of this product. Happy shopping!

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