When the need arises to control the fluid level, many do this work manually, but this is extremely ineffective, takes a lot of time and effort, and the consequences of oversight can be very expensive: for example, a flooded apartment or a burnt out pump. This can be easily avoided by using float water level sensors. These are devices that are simple in design and operating principle and are affordable.
At home, sensors of this type allow you to automate processes such as:
- monitoring the liquid level in the supply tank;
- pumping groundwater from the cellar;
- turning off the pump when the level in the well falls below the permissible level, and some others.
Operating principle of a float sensor
An object is placed in the liquid and does not sink in it. This could be a piece of wood or foam, hollow sealed plastic sphere or metal and much more. When the liquid level changes, this object will rise or fall with it. If the float is connected to the actuator, it will act as a water level sensor in the tank.
Equipment classification
Float sensors can independently monitor the liquid level or send a signal to the control circuit. According to this principle, they can be divided into two large groups: mechanical and electrical.
Mechanical devices
Mechanical valves include a wide variety of float valves for the water level in the tank. The principle of their operation is that the float is connected to a lever; when the liquid level changes, the float moves up or down this lever, and it, in turn, acts on the valve, which shuts off (opens) the water supply. Such valves can be seen in toilet flush tanks. They are very convenient to use where you need to constantly add water from the central water supply system.
Mechanical sensors have a number of advantages:
- simplicity of design;
- compactness;
- safety;
- autonomy - do not require any sources of electricity;
- reliability;
- cheapness;
- ease of installation and configuration.
But these sensors have one significant drawback: they can control only one (upper) level, which depends on the installation location, and regulate it, if possible, then within very small limits. Such a valve can be sold called “float valve for containers”.
Electrical sensors
An electric liquid level sensor (float) differs from a mechanical one in that it itself does not shut off the water. The float, moving when the amount of liquid changes, affects the electrical contacts that are included in the control circuit. Based on these signals, the automatic control system makes a decision on the need for certain actions. In the simplest case, such a sensor has a float. This float acts on the contact through which the pump is turned on.
Reed switches are most often used as contacts. A reed switch is a sealed glass bulb with contacts inside. Switching of these contacts occurs under the influence of a magnetic field. Reed switches are miniature in size and can be easily placed inside a thin tube made of non-magnetic material (plastic, aluminum). A float with a magnet moves freely along the tube under the influence of liquid, and when it approaches, the contacts are activated. This entire system is installed vertically in the tank. By changing the position of the reed switch inside the tube, you can adjust the moment the automation operates.
If you need to monitor the upper level in the tank, then the sensor is installed at the top. As soon as the level drops below the set level, the contact closes and the pump turns on. The water will begin to increase, and when the water level reaches the upper limit, the float will return to its original state and the pump will turn off. However, in practice such a scheme cannot be used. The fact is that the sensor is triggered by the slightest change in the level, after which the pump turns on, the level rises, and the pump turns off. If the water flow from the tank is less than the supply, a situation arises when the pump is constantly turned on and off, while it quickly overheats and fails.
Therefore, water level sensors to control the pump they work differently. There are at least two contacts in the container. One is responsible for the upper level; it turns off the pump. The second determines the position of the lower level, upon reaching which the pump turns on. Thus, the number of starts is significantly reduced, which ensures reliable operation of the entire system. If the level difference is small, then it is convenient to use a tube with two reed switches inside and one float that connects them. If the difference is more than a meter, two separate sensors are used, installed at the required heights.
Despite their more complex design and the need for a control circuit, electric float sensors allow fully automated liquid level control.
If you connect light bulbs through such sensors, then they can be used to visually monitor the amount of liquid in the tank.
Homemade float switch
If you have the time and desire, then you can make a simple float water level sensor with your own hands, and the costs for it will be minimal.
Mechanical system
In order to simplify as much as possible design, we will use a ball valve (faucet) as a locking device. The smallest valves (half-inch or smaller) work well. This type of faucet has a handle that closes it. To convert it into a sensor, you need to extend this handle with a strip of metal. The strip is attached to the handle through holes drilled in it with the appropriate screws. The cross-section of this lever should be minimal, but it should not bend under the influence of the float. Its length is about 50 cm. The float is attached to the end of this lever.
As a float you can use a two-liter plastic bottle from soda. The bottle is half filled with water.
You can check the operation of the system without installing it in the tank. To do this, install the faucet vertically and place the lever with the float in a horizontal position. If everything is done correctly, then under the influence of the mass of water in the bottles, the lever will begin to move down and take a vertical position, and the valve handle will turn with it. Now submerge the device in water. The bottle should float up and turn the valve handle.
Since valves vary in size and the amount of force required to switch them, the system may need to be adjusted. If the float cannot turn the valve, you can increase lever length or take a larger bottle.
We mount the sensor in the container at the required level in a horizontal position, while in the vertical position of the float the valve should be open, and in the horizontal position it should be closed.
Electric type sensor
For self-production of the sensor of this type, in addition to the usual tool, you will need:
The manufacturing sequence is as follows:
When the liquid level changes, the float moves along with it, which acts on an electrical contact to control the water level in the tank. A control circuit with such a sensor may look like the one shown in the figure. Points 1, 2, 3 are the connection points for the wire that comes from our sensor. Point 2 is a common point.
Let's consider the principle of operation of a homemade device. Let's say at the moment of switching on the tank empty, the float is in the low level position (LL), this contact closes and supplies power to the relay (P).
The relay operates and closes contacts P1 and P2. P1 is a self-locking contact. It is needed so that the relay does not turn off (the pump continues to work) when the water begins to rise and the contact of the low pressure unit opens. Contact P2 connects the pump (H) to the power source.
When the level rises to the upper value, the reed switch will operate and open its contact VU. The relay will be de-energized, it will open its contacts P1 and P2, and the pump will turn off.
As the amount of water in the tank decreases, the float will begin to fall, but until it takes the lower position and closes the NU contact, the pump will not turn on. When this happens, the work cycle will repeat again.
This is how a water level control float switch works.
During operation, it is necessary to periodically clean the pipe and float from dirt. Reed switches can withstand a huge number of switchings, so this sensor will last for many years.
" It happens that you need to find out how much water is left in some opaque container. For example, a tank, barrel or any other, buried in the ground or raised to a height so that its contents are not visible. Then a water level sensor will come to the rescue. The circuit is so simple that even someone who has just picked up a soldering iron can repeat it. It consists of only 10 resistors, 3 transistors and 3 LEDs.
Let's start building the sensor circuit. First, we cut the board 30 mm by 45 mm. Then we will draw the paths, as in the photo. It is advisable to paint with paint or nail polish. But I only had a marker on hand (I would like to note that only a permanent marker will do). If you draw with a marker, then a marker purchased from a CD or computer store will hold up best. Once you've drawn, start etching.
I poisoned with hydrogen peroxide, since there is no ferric chloride or copper sulfate. I poured 50 ml of 3% hydrogen peroxide, then added 1 tablespoon of salt and 2 tablespoons of citric acid. Mixed until everything was dissolved. With occasional gentle rocking, I etched the board in about 50 minutes.
Let's start soldering the circuit. For this we need: 3 resistors with a resistance of 10 kOhm, 3 resistors with a resistance of 1 kOhm, 2 green and 1 red LEDs, 4 resistors of 300 Ohms. Having carefully soldered everything in, solder the wires and connect the battery. We cut the wires every 2 centimeters.
Ready! Now we lower the wires into the glass and gradually pour water. For clarity, I slightly tinted the water. As you can see, everything works great.
When the glass contains 1/3 of water, only the red LED lights up. When 2/3, the green light also lights up. And when the glass is filled to the top line, all the LEDs light up. in my case, I assembled a circuit with only 3 LEDs, but you can do more - at least 10. Then the water level will be visible more accurately. I would also like to add that the case was used under a corrector. I assembled the diagram: bkmz268
Discuss the article WATER LEVEL INDICATOR
In production, there is often a need to measure the level of liquids (water, gasoline, oil). In everyday life, most often you need to determine the height of water in a container; for this purpose, special devices are used - level meters and alarms. Measuring devices are divided into several types; they are purchased in stores, but for home use the easiest way is to make a water level sensor with your own hands.
Types of sensors
Sensors differ in the method of measuring liquid level and are divided into two types: alarms and level meters. Alarms monitor the specified filling point of the container and, when the required volume of liquid is reached, stop its flow (for example, a float in a toilet tank).
Level gauges continuously monitor the degree of filling of the tank (for example, a sensor on a mine drainage system).
According to the principle of operation, water level sensors in the tank are divided into these varieties:
These are the most common level sensors; in addition to them, there are capacitive, hydrostatic, radioisotope and other types of devices that are used in various industries.
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 type of liquid medium and its density, the level of danger to humans. What matters is the material of the container and its volume - the operating principle of the selected sensor depends on these parameters.
The next point to pay attention to is 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.
DIY making
The easiest way is to make your own float sensor for the water level in the tank, or a fill indicator.
The principle of operation of such a device consists in the fact that the float floats up in the liquid, when the container is filled to its maximum, it closes the contacts and signals that the water level is sufficient.
Manufacturing sequence:
The given sensor manufacturing scheme is the simplest; it is used for small containers.
The disadvantage of such a device is that it does not allow the pump to automatically turn off. To stop the flow of water into the tank, alarms are made using magnets and reed switches.
To make a sensor or indicator of the water level in a tank, tank, swimming pool or other container, you can use the 4093 microcircuit (domestic 561TL1) or on an Arduino microcontroller. Let's start with the first option.
Materials required for the sensor
- 2 4093 chips;
- 2 sockets for microcircuits;
- 7 x 500 ohm resistors;
- 7 x 2.2 MΩ resistors;
- battery 9 V;
- battery socket;
- circuit board 10 x 5 cm;
- 8 brass sensor screws;
- double-sided tape or screws for attaching the box to the wall;
- network cable. The length of the cable depends on the distance from the water tank to the location where the display will be located.
So the base is CI4093, which has four elements. This project uses two chips. Here we have ports with one input at a high level, and the others connected through a resistor, providing a high logic level. By placing a zero input signal into this logic, the inverter output will go high and turn on the LED. A total of seven out of eight elements were used due to cable network limitations.
On the side there is a line of LEDs of different colors indicating the water level. Red indicators - there is very little water, yellow - the tank is half empty, green - full. The central large button is used to connect the pump and inflate the tank.
The circuit only works when you press the center button. The rest of the time she is in standby mode. But even when the indication circuit is triggered, the current is minimal and the battery will last for a long time.
Sensor connection diagram
The wires run inside the pipes. Try to position the sensors in such a way that water entering the field using the float valve cannot pass by the sensors. Sand was poured inside the pipe with sensors to create the required weight.
Once assembled, the circuit is in a box and mounted on the wall.
Second version of the level sensor circuit
This is a fully functional water level controller controlled by an Arduino MCU. The circuit displays the water level in the tank and switches the motor when the water level drops below a preset level. It automatically turns off the motor when the tank is full. Water level and other important data are displayed on a 16x2 dot LCD display. In the author's version, the circuit controls the water level in the drainage tank (reservoir). If the tank level is low, the pump motor will not turn on, which protects the engine from idling. Additionally, an audible alarm is generated when the level in the drain tank is too low.
The water level circuit using an Arduino controller is shown above. The sensor assembly consists of four aluminum wires 1/4, 1/2, 3/4 long and a full level in the tank. The dry ends of these wires are connected to the analog inputs A1, A2, A3 and A4 of the Arduino respectively. The fifth wire is located at the bottom of the tank. Resistors R6 - R9 reduce the potential of the inputs. The dry end of the wire is connected to +5V DC. When water touches a particular probe, an electrical connection occurs between the probe and +5V because water has some electrical conductivity. As a result, current flows through the probe and this current is converted into a voltage proportional to it. The Arduino reads the voltage drop across each of the input resistors to sense the water level in the tank. Transistor Q1 turns on the buzzer, resistor R5 limits the base current of Q1. Transistor Q2 drives the relay. Resistor R3 limits the base current of Q2. Variable R2 is used to adjust the contrast of the LCD display. resistor R1 limits the current through its LED backlight. Resistor R4 limits the current through the power LED. Full
To regulate and control the level of liquid or solid substance (sand or gravel) in production or at home, a special device is used. It is called a water level sensor (or other substance of interest). There are several varieties of such devices, which differ significantly from each other in their operating principles. How the sensor works, the advantages and disadvantages of its varieties, what subtleties you should pay attention to when choosing a device, and how to make a simplified model with a relay with your own hands, read in this article.
The water level sensor is used for the following purposes:
Possible methods for determining tank load
There are several methods for measuring liquid level:
- Contactless- often devices of this type are used to control the level of viscous, toxic, liquid or solid, granular substances. These are capacitive (discrete) devices, ultrasonic models;
- Contact- the device is located directly in the tank, on its wall, at a certain level. When the water reaches this indicator, the sensor is triggered. These are float, hydrostatic models.
Based on the principle of operation, the following types of sensors are distinguished:
- Float type;
- Hydrostatic;
- Capacitive;
- Radar;
- Ultrasonic.
Briefly about each type of device
Float models are discrete and magnetostrictive. The first option is cheap, reliable, and the second is expensive, complex in design, but guarantees an accurate level reading. However, a common disadvantage of float devices is the need for immersion in liquid.
Float sensor for determining the liquid level in the tank
- Hydrostatic devices - in them all attention is paid to the hydrostatic pressure of the liquid column in the tank. The sensitive element of the device senses pressure above itself and displays it according to a diagram to determine the height of the water column.
The main advantages of such units are compactness, continuity of operation and affordability. But they cannot be used in aggressive conditions, because they cannot do without contact with liquid.
Hydrostatic liquid level sensor
- Capacitive devices - plates are provided to control the water level in the tank. By changing the capacity indicators, you can judge the amount of liquid. The absence of moving structures and elements, the simple design of the device guarantees durability and reliable operation of the device. But one cannot fail to note the disadvantages - this is the necessity of immersion in liquid, and demanding temperature conditions.
- Radar devices - determine the degree of increase in water by comparing the frequency shift, the delay between the radiation and the achievement of the reflected signal. Thus, the sensor acts as both an emitter and a reflection collector.
Such models are considered the best, accurate, reliable devices. They have a number of advantages:
The only disadvantage of the model is its high cost.
Radar tank liquid level sensor
- Ultrasonic sensors - the principle of operation and the design of the device are similar to radar devices, only ultrasound is used. The generator creates ultrasonic radiation, which, upon reaching the surface of the liquid, is reflected and reaches the sensor receiver after some time. After some mathematical calculations, knowing the time delay and speed of the ultrasound, the distance to the water surface is determined.
The advantages of a radar sensor are also inherent in the ultrasonic version. The only thing is that the indicators are less accurate and the operation scheme is simpler.
Subtleties of choosing such devices
When purchasing a unit, pay attention to the functionality of the device and some of its indicators. Extremely important questions when purchasing a device are:
Options for sensors for determining the level of water or solids
DIY liquid level sensor
You can make a basic sensor to determine and control the water level in a well or tank with your own hands. To perform the simplified version you need:
A self-made device can be used to regulate water in a tank, well or pump.
