Do-it-yourself automation for filling containers with water. Automatic filling of the tank with water in the garden. The nuances of the electrical circuit of automatic control

One of the most annoying household problems is the lack of water in the tap. It is easy to survive the absence of light or gas, but water is an indispensable component of human life, and when it is not there or not enough, problems begin. You can keep several water containers in the house all the time, for example, plastic bottles, but it is much more practical to determine what kind of storage tank for water supply and the system diagram for a private house are needed so as not to lose comfort and continue to use household appliances and a sink with a bathroom, no matter how what never happened.

Why is it needed and how to use it

If for some reason the pump in the autonomous water supply system does not work, or there is no pressure in the centralized city water supply, then it can be supplied to the sink or toilet bowl from a previously collected reserve tank. Simply put, it is better to always have a supply of drinking water in the house and use it in emergency situations.

For the convenience of using the reserve water supply, the storage tank must be integrated into the water supply system so that it is either automatically used in the absence of external pressure, or it can be activated by simply turning the valve.

There are many variations on how to install and connect a storage tank, depending on the type of water source, the possible location of the tank, and even the layout of the house. It is enough to choose the appropriate option and decide on the type of the storage tank itself.

Types

The storage tank can be a tank with a sufficient internal volume, made of a material resistant to corrosion and safe for storing drinking water. The following materials are used:

• polyvinyl chloride;
• cross-linked polyethylene of high or low pressure;
• polypropylene;
• stainless steel;
• steel coated with waterproof varnishes and ceramic coatings.

Although galvanized steel is resistant to corrosion and waterproof, over time the protective layer of zinc can become thinner, especially at the joints and welds.

By design, allocate:

• open containers that have a neck with or without a lid, but with sealed walls and a bottom;
• closed fully sealed containers of membrane type.

In the first case, everything is simple, the entire internal volume is filled with water and, if necessary, drains through a pipe fixed at the lowest point.

In the case of membrane storage tanks, the usable volume is at least a third less than the volume of the entire structure. Part of the volume is allocated under the air chamber, separated from the water by a strong elastic membrane. As the container fills with water, the membrane presses on the air chamber, creating excess pressure. When it is required to receive water back, the valve opens, and it enters the water supply system under the action of the accumulated pressure.

Bottom or top

There are three options for connecting the storage tank and using the water supply:

• Top location of the container. In this case, the water intake is carried out under the action of gravity. The higher the accumulator is located in relation to the consumer, the stronger the water pressure. Every 10 meters of altitude adds 0.1 atmosphere, or about 1 bar.
• The lower location of a simple storage tank. Gravity will no longer help, and a pump is used to supply the water supply, raising the pressure to the optimum level.
• Membrane-type storage tanks themselves create the required pressure for water supply. The lower location at the level of the consumer is optimal for them, since there will be no advantage from installation in an attic or tower.

How to determine the best option?

If the house has several floors and it is possible to place the storage tank in the attic, then this will allow you to do without additional installation of the pump, and you do not need to spend money on an expensive membrane tank. In fact, this is an analogue of a water tower. However, raise the container so high as to provide a comfortable pressure at the level of 2-2.5 atm. it's still difficult. Moreover, the question arises of warming the tank so that in winter the water in it does not freeze.

In the event of an emergency shutdown of the available water pressure of 0.2-0.3 atm. it will be quite enough to use the faucet in the sink, toilet or even shower, but it will not be possible to use some household appliances, such as a washing machine or dishwasher, which require more pressure to operate the solenoid valves.

Installing the tank at the level with the consumer is suitable in cases where it is not possible to raise the tank to the attic or at least one floor higher. The same applies to the installation of a storage tank in the apartment. You will need a small pump to supply water to the water supply under pressure. To ensure adequate operation, the pump will require an expansion membrane tank.

A storage tank with a membrane is perfect for storing water both when using a centralized water supply system and in an autonomous system. However, it does not require additional equipment or top location. However, its cost is much higher than any conventional storage tank, even when combined with a simple pump.

Volume of the tank

In the event of problems on the city water supply line and water cuts, repairs are usually completed in a day or two. However, accidents also happen on holidays, and in places where a quick repair is simply impossible, then you have to wait much longer. The optimal supply of water for 2-3 days is based on the use of the toilet, maintaining personal hygiene and cooking.

For a family of three, 100 liters per day is enough when using water in economy mode. For one wash, approximately 80 liters of water are required, you can find out more precisely in the passport for the washing machine. Same for dishwasher.

It turns out that for 2-3 days when using household appliances, you need to look for a storage capacity of at least 500 liters, half a cubic meter.

However, there are a number of limitations:

• The larger the volume of water and the storage tank of an open type, the faster it will begin to overgrow with sediment. It is not recommended to use containers with a volume of more than 200-250 liters in everyday life for long-term storage of water.
• The margin of safety of the ceiling and load-bearing walls should be taken into account. The installation of the tank must be laid at the design stage of the house.
• When using autonomous water supply, the volume of the storage tank, especially of the membrane type, should not exceed the debit of the well. If this rule cannot be observed, then the pump must be protected from idling.

Membrane-type storage tanks are limited in their volume and are not able to give up the entire supply of stored liquid. To form a stock of more than 300 liters, you will have to connect several tanks of a smaller capacity in parallel to each other.

General connection rules

A water tank is installed on a prepared site: a concrete base tied with a foundation, or a reinforced metal frame made of a profiled pipe. The design must withstand one and a half weight of the tank and the water in it when completely filled.

The inlet pipe can be of any suitable diameter, water is supplied under pressure. The outlet pipe and the pipe to the water supply are chosen with a diameter one and a half to two times larger than the cross section of the main line. The optimal size is 32 mm.

Insulation, even of the highest quality, only slows down the temperature drop in the tank. To prevent freezing of water when installing the tank in an unheated attic or on the roof, any suitable heating system for pipes and the tank itself should be used.

With centralized water supply

Any type of storage tank connection requires a check valve at the entrance to the house or apartment. It is the valve that will prevent the flow of stored water back into the pipeline, and not to the consumer.

Top connection

The tank is installed under the ceiling of the first floor, the floor above the bathroom and kitchen or in the attic. The tank should have a fitting at the top for water supply, another one a little higher for discharge into the sewer when overflowing, and a fitting at the very bottom for water intake.

After entering the coarse filter of the shut-off valve, the meter and the check valve, a tee is installed, from which the pipe goes to the tank inlet pipe, a shut-off valve or a controlled valve is installed in front of the fitting.

A shut-off valve is connected to the outlet fitting and the pipe is lowered back to the water supply, to which it is connected by means of a tee.

The excess discharge hose is lowered into the sewer or led out of the house into the front garden or drainage system.

To control the filling, a mechanical valve with a float is used, similar to those used in the toilet bowl.

To use the stored water, it is enough to open the outlet valve.

Bottom connection

Connection is identical to the first option. However, a pump must be installed at the outlet to create additional pressure in the water supply. Before each use of water, you will have to turn on the pump first.

A ready-made pumping station or the addition of a pump with a membrane-type expansion tank and a pressure switch will help simplify life.

Bottom connection of storage tank with membrane

To connect the tank, only one pipe is used, connected to the water supply through a tee with a valve. The insert is also carried out after the filter, counter and check valve.

Before use, the pressure in the air chamber must be adjusted. This must be done strictly in accordance with the instructions for the selected model. The normal pressure in the water supply is preliminarily studied, moreover, taking into account fluctuations during the day. As a result, the average value is taken, which is used to adjust the tank. This is the only way to use the maximum useful volume of the tank.

For autonomous water supply

As in the case of centralized water supply, there are several connection options.

Water tower

The storage tank is installed at a level of 15-20 meters above ground level on a reinforced tower or attic. Water from a borehole pump or pumping station is supplied directly to the tank, and from there it is distributed to the bathroom and kitchen in the house. The pressure in the system is provided by the height difference between the water level in the tank and the mixer tap in the house.

The disadvantage is the constant passage of water through the tank, which will cause sediment to accumulate over time, even if a filter system is pre-installed.

The advantage is the simplicity of the design and the minimum of expensive elements, with the exception of the tower structure itself and the obligatory insulation of the tank to protect it from freezing even when it is placed in the attic.

Bottom tank connection

The tank is installed flush with the pumping station or on the ground floor in the house. It is filled during normal operation of the pump due to water from the well. The limiter is a float switch.

This option saves with excessive water consumption and a decrease in the water level in a well or well. However, it is useless when the electricity is turned off, since a pump is required to supply the end user with water from the reserve.

Membrane storage tank

A membrane tank for storing water is installed after the pumping station and the check valve, with a bottom connection. If the pumping station for some reason does not work and does not maintain pressure in the system, then water comes from the storage tank.

To automate many production processes, it is necessary to control the water level in the tank, the measurement is carried out using a special sensor that gives a signal when the process medium reaches a certain level. It is impossible to do without level gauges in everyday life, a vivid example of this is the shut-off valves of the toilet bowl or automation to turn off the well pump. Let's look at the different types of level sensors, their design and principle of operation. This information will be useful when choosing a device for a specific task or making a sensor with your own hands.

Design and principle of operation

The design of measuring devices of this type is determined by the following parameters:

• Functionality, depending on this device, is usually divided into signaling devices and level gauges. The former monitor a specific tank filling point (minimum or maximum), the latter continuously monitor the level.
• The principle of operation, it can be based on: hydrostatics, electrical conductivity, magnetism, optics, acoustics, etc. Actually, this is the main parameter that determines the scope.
• Measurement method (contact or non-contact).

In addition, the design features determine the nature of the process environment. It is one thing to measure the height of drinking water in a tank, and another thing to check the filling of tanks for industrial effluents. In the latter case, appropriate protection is needed.

Types of level sensors

Depending on the principle of operation, signaling devices are usually divided into the following types:

• float type;
• using ultrasonic waves;
• devices with capacitive level detection principle;
• electrode;
• radar type;
• operating on the hydrostatic principle.

Since these types are the most common, we will consider each of them separately.

float

This is the simplest, but nevertheless effective and reliable way to measure liquid in a tank or other container. An example implementation can be found in Figure 2.

The design consists of a float with a magnet and two reed switches installed at control points. Briefly describe the principle of operation:

• The tank is emptied to a critical minimum (A in Fig. 2), while the float drops to the level where the reed switch 2 is located, it turns on the relay that supplies power to the pump that pumps water from the well.
• The water reaches the maximum mark, the float rises to the location of the reed switch 1, it works and the relay turns off, respectively, the pump motor stops working.

It is quite simple to make such a reed switch on your own, and its setting comes down to setting on-off levels.

Note that if you choose the right material for the float, the water level sensor will work even if there is a layer of foam in the tank.

Ultrasonic

This type of meter can be used for both liquid and dry applications and can have an analog or discrete output. That is, the sensor can limit the filling to a certain point or monitor it constantly. The device includes an ultrasonic emitter, a receiver and a signal processing controller. The principle of operation of the signaling device is shown in Figure 3.

The system works as follows:

• an ultrasonic pulse is emitted;
• reflected signal is received;
• the duration of the signal attenuation is analyzed. If the tank is full, it will be short (A fig. 3), and as it empties it will begin to increase (B fig. 3).

The ultrasonic signaling device is non-contact and wireless, so it can be used even in aggressive and explosive environments. After the initial adjustment, such a sensor does not require any specialized maintenance, and the absence of moving parts significantly extends the service life.

Electrode

Electrode (conductometric) signaling devices allow you to control one or more levels of an electrically conductive medium (that is, they are not suitable for measuring the filling of a tank with distilled water). An example of using the device is shown in Figure 4.

In the given example, a three-level signaling device is used, in which two electrodes control the filling of the tank, and the third one is an emergency one, to enable the intensive pumping mode.

capacitive

With the help of these signaling devices, it is possible to determine the maximum filling of the container, and both liquid and loose substances of a mixed composition can act as a technological medium (see Fig. 5).

The principle of operation of the signaling device is the same as that of a capacitor: the capacitance is measured between the plates of the sensitive element. When it reaches the threshold value, a signal is sent to the controller. In some cases, the “dry contact” version is involved, that is, the level gauge works through the tank wall in isolation from the process medium.

These devices can operate in a wide temperature range, they are not affected by electromagnetic fields, and operation is possible at a great distance. Such characteristics significantly expand the scope of application up to severe operating conditions.

Radar

This type of signaling devices can really be called universal, since it can work with any process medium, including aggressive and explosive ones, and pressure and temperature will not affect the readings. An example of the operation of the device is shown in the figure below.

The device emits radio waves in a narrow range (several gigahertz), the receiver catches the reflected signal and determines the capacity of the container by its delay time. The measuring transducer is not affected by pressure, temperature, or the nature of the process fluid. Dust also does not affect the readings, which cannot be said about laser signaling devices. It is also necessary to note the high accuracy of devices of this type, their error is no more than one millimeter.

Hydrostatic

These alarms can measure both the limit and the current filling of tanks. Their principle of operation is shown in Figure 7.

The device is built on the principle of measuring the pressure level produced by a liquid column. Acceptable accuracy and low cost have made this type quite popular.

Within the framework of the article, we cannot examine all types of signaling devices, for example, rotary-flag ones, for determining bulk solids (there is a signal when the fan blade gets stuck in a loose medium, after the pit has been pulled out). It also makes no sense to consider the principle of operation of radioisotope meters, all the more so to recommend them for checking the level of drinking water.

How to choose?

The choice of a water level sensor in the tank depends on many factors, the main ones are:

• Liquid composition. Depending on the content of foreign impurities in the water, the density and electrical conductivity of the solution may change, which is likely to affect the readings.
• The volume of the tank and the material from which it is made.
• The functional purpose of the container for the accumulation of liquid.
• The need to control the minimum and maximum levels, or monitoring of the current state is required.
• Admissibility of integration into the automated control system.
• Switching capabilities of the device.

This is not a complete list for the selection of measuring instruments of this type. Naturally, for domestic purposes, it is possible to significantly reduce the selection criteria by limiting them to the volume of the tank, the type of operation and the control scheme. A significant reduction in requirements makes it possible to independently manufacture such a device.

We make a water level sensor in the tank with our own hands

Suppose there is a task to automate the operation of a submersible pump for the water supply of a summer residence. As a rule, water enters the storage tank, therefore, we need to make sure that the pump turns off automatically when it is full. It is not at all necessary to buy a laser or radar level indicator for this purpose; in fact, you do not need to purchase any. A simple task requires a simple solution, it is shown in Figure 8.

To solve the problem, you will need a magnetic starter with a 220 volt coil and two reed switches: the minimum level - for closing, the maximum - for opening. The connection diagram of the pump is simple and, importantly, safe. The principle of operation was described above, but we repeat it:

• As the water fills, the float with the magnet gradually rises until it reaches the maximum level reed switch.
• The magnetic field opens the reed switch, turning off the starter coil, which leads to a de-energization of the motor.
• As the water flows, the float drops until it reaches the minimum mark opposite the lower reed switch, its contacts close, and voltage is applied to the starter coil, which supplies voltage to the pump. Such a water level sensor in the tank can work for decades, unlike an electronic control system.

Water supply and drainage is an integral part of everyday life and production. Almost everyone who was engaged in farming or landscaping at least once faced the problem of maintaining the water level in a particular container. Some do it manually by opening and closing valves, but it is much easier and more efficient to use an automatic water level sensor for this purpose.

Types of level sensors

Depending on the tasks set, contact and non-contact sensors are used to control the liquid level. The former, as you might guess from their name, have contact with a liquid, the latter receive information remotely using indirect measurement methods - the transparency of the medium, its capacitance, electrical conductivity, density, etc. According to the principle of operation, all sensors can be divided into 5 main types:

1. Float.
2. Electrode.
3. Hydrostatic.
4. Capacitive.
5. radar.

The first three can be attributed to contact type devices, since they directly interact with the working medium (liquid), the fourth and fifth are non-contact.

Float sensors

Perhaps the simplest in design. They are a float system that is located on the surface of the liquid. As the level changes, the float moves, one way or another closing the contacts of the control mechanism. The more contacts are located along the path of the float, the more accurate the indications of the signaling device:

The principle of operation of the float sensor of the water level in the tank

The figure shows that the indications of the indicator of such a device are discrete, and the number of level values ​​depends on the number of switches. In the above diagram, there are two of them - upper and lower. This, as a rule, is quite enough to automatically maintain the level in the specified range.

There are float devices for continuous remote control. In them, the float controls the rheostat engine, and the level is calculated based on the current resistance. Until recently, such devices were widely used, for example, to measure the amount of gasoline in the fuel tanks of cars:

Rheostatic level gauge device, where:

• 1 - wire rheostat;
• 2 - rheostat slider, mechanically connected to the float.

Electrode level sensors

Devices of this type use the electrical conductivity of the fluid and are discrete. The sensor consists of several electrodes of various lengths immersed in water. Depending on the level in the liquid, there is one or another number of electrodes.

Three-electrode system of liquid level sensors in the tank

In the figure above, the two right sensors are immersed in water, which means that there is water resistance between them - the pump is stopped. Once the level drops, the middle sensor will be dry and the circuit resistance will increase. Automation will start the boost pump. When the container is full, the shortest electrode will fall into the water, its resistance relative to the common electrode will decrease and the automation will stop the pump.

It is quite clear that the number of control points can be easily increased by adding additional electrodes and appropriate control channels to the design, for example, for an overflow or drying out alarm.

Hydrostatic control system

Here, the sensor is an open tube in which a pressure sensor of one type or another is installed. As the level increases, the height of the water column in the tube changes, and hence the pressure on the sensor:

The principle of operation of the hydrostatic liquid level control system

Such systems have a continuous characteristic and can be used not only for automatic control, but also for remote level control.

Capacitive measuring method

The principle of operation of a capacitive sensor with a metal (left) and a dielectric bath

Inductive pointers work on a similar principle, but in them the role of the sensor is played by a coil, the inductance of which changes depending on the presence of liquid. The main disadvantage of such devices is that they are suitable only for monitoring substances (liquids, bulk materials, etc.) that have a sufficiently high magnetic permeability. In everyday life, inductive sensors are practically not used.

radar control

The main advantage of this method is the absence of contact with the working environment. Moreover, the sensors can be separated from the liquid, the level of which must be controlled, far enough - meters. This allows the use of radar-type sensors to monitor extremely aggressive, toxic or hot liquids. Their very name speaks about the principle of operation of such sensors - radar. The device consists of a transmitter and receiver assembled in one housing. The first emits one or another type of signal, the other receives the reflected one and calculates the delay time between the sent and received pulses.

The principle of operation of the radar type ultrasonic level switch

Depending on the tasks set, the signal can be light, sound, radio emission. The accuracy of such sensors is quite high - millimeters. The only, perhaps, disadvantage can be considered the complexity of the radar control equipment and its rather high cost.

Homemade liquid level regulators

Due to the fact that some of the sensors are extremely simple in design, It is not difficult to create a water level switch with your own hands. Working in conjunction with water pumps, such devices will allow you to fully automate the process of pumping water, for example, into a country water tower or an autonomous drip irrigation system.

Float pump control

To implement this idea, a homemade reed switch water level sensor with a float is used. It does not require expensive and scarce components, is easy to repeat and quite reliable. First of all, it is worth considering the design of the sensor itself:

The design of a two-level float sensor of water in the tank

It consists of the actual float 2, which is fixed on the movable rod 3. The float is located on the surface of the water and, depending on its level, moves up / down together with the rod and the permanent magnet 5 fixed to it in guides 4 and 5. In the lower position, when the liquid level is minimal, the magnet closes the reed switch 8, and in the upper one (the tank is full) - the reed switch 7. The length of the rod and the distance between the guides is selected based on the height of the water tank.

It remains to assemble a device that will automatically turn the boost pump on and off depending on the state of the contacts. Its scheme looks like this:

Water pump control circuit

Let's assume that the tank is completely filled, the float is in the upper position. Reed switch SF2 is closed, transistor VT1 is closed, relays K1 and K2 are disabled. The water pump connected to connector XS1 is de-energized. As the water flows, the float, and with it the magnet, will lower, the reed switch SF1 will open, but the circuit will remain in the same state.

As soon as the water level falls below the critical level, the reed switch SF1 closes. Transistor VT1 will open, relay K1 will work and will become self-locking with contacts K1.1. At the same time, the contacts K1.2 of the same relay will supply power to the starter K2, which turns on the pump. Water pumping has begun.

As the level increases, the float will begin to rise., contact SF1 will open, but the transistor blocked by contacts K1.1 will remain open. As soon as the capacitance is full, the SF2 contact closes and forcibly closes the transistor. Both relays will release, the pump will turn off, and the circuit will go into standby mode.

When repeating the circuit in place of K1, you can use any low-power electromagnetic relay for an actuation voltage of 22-24 V, for example, RES-9 (RS4.524.200). As K2, an RMU (RS4.523.330) or any other for a response voltage of 24 V is suitable, the contacts of which withstand the starting current of the water pump. Reed switches will go to any, working on a circuit or switching.

Level switch with electrode sensors

With all its dignity and simplicity, the previous design of the level gauge for tanks also has a significant drawback - mechanical components operating in water and requiring constant maintenance. This disadvantage is absent in the electrode design of the machine. It is much more reliable than mechanical, does not require any maintenance, and the circuit is not much more complicated than the previous one.

Here, three electrodes made of any conductive stainless material are used as sensors. All electrodes are electrically isolated from each other and from the container body. The design of the sensor is clearly visible in the figure below:

The design of a three-electrode sensor, where:

• S1 - common electrode (always in water)
• S2 – minimum sensor (tank empty);
• S3 - maximum level sensor (tank full);

The pump control scheme will look like this:

Scheme of automatic control of the pump using electrode sensors

If the tank is full, then all three electrodes are in water and the electrical resistance between them is small. In this case, the transistor VT1 is closed, VT2 is open. Relay K1 is turned on and de-energizes the pump with its normally closed contacts, and connects sensor S2 in parallel with S3 with normally open contacts. When the water level starts to drop, electrode S3 is exposed, but S2 is still in the water and nothing happens.

The water continues to be consumed and finally the S2 electrode is exposed. Thanks to the resistor R1, the transistors go into the opposite state. The relay releases and starts the pump, at the same time turning off the S2 sensor. The water level gradually rises and first closes the electrode S2 (nothing happens - it is turned off by contacts K1.1), and then S3. The transistors are switched again, the relay is activated and turns off the pump, at the same time putting sensor S2 into operation for the next cycle.

The device can use any low-power relay that operates from 12 V, the contacts of which are able to withstand the current of the pump starter.

If necessary, the same scheme can be used for automatic pumping of water, say, from the basement. To do this, the drainage pump must be connected not to normally closed, but to normally open contacts of relay K1. The scheme does not require any other changes.