Expansion tank for water supply of open type. Expansion tanks for drinking water systems

In order for the pump not to turn on every time a tap is opened in the house, a hydraulic accumulator is installed in the system. It contains a certain amount of water, sufficient for a small flow. This allows you to practically get rid of short-term switching on of the pump. Installing a hydraulic accumulator is not difficult, but a certain number of devices will be required - at least - a pressure switch, and it is also desirable to have a pressure gauge and an air vent.

Functions, purpose, types

Place of installation - in the pit or in the house

In the water supply system of a private house without a hydraulic accumulator, the pump turns on whenever water flows somewhere. These frequent inclusions lead to wear of the equipment. And not only the pump, but the entire system as a whole. After all, every time there is an abrupt increase in pressure, and this is a water hammer. To reduce the number of pump turns on and smooth out the water hammer, a hydraulic accumulator is used. The same device is called an expansion or membrane tank, hydraulic tank.

Purpose

We found out one of the functions of hydraulic accumulators - to smooth out hydraulic shocks. But there are others:

Not surprisingly, in most private water systems this device present - there are many advantages from its use.

Kinds

The hydraulic accumulator is a tank of sheet metal divided into two parts by an elastic membrane. There are two types of membrane - diaphragm and balloon (pear). The diaphragm is attached across the tank, the balloon in the form of a pear is fixed at the inlet around the inlet pipe.

By appointment, they are of three types:

• for cold water;
• for hot water;
• for heating systems.

Hydraulic tanks for heating are painted red, tanks for plumbing are painted blue. Expansion tanks for heating are usually smaller and more low price. This is due to the material of the membrane - for water supply it must be neutral, because the water in the pipeline is drinking.

According to the type of location, accumulators are horizontal and vertical. Vertical ones are equipped with legs, some models have plates for hanging on the wall. It is the models elongated upwards that are more often used when independent creation plumbing systems of a private house - they occupy less space. The connection of this type of accumulator is standard - through a 1-inch outlet.

Horizontal models are usually completed with pumping stations with surface-type pumps. Then the pump is placed on top of the tank. It turns out compact.

Principle of operation

Radial membranes (in the form of a plate) are used mainly in gyroaccumulators for heating systems. For water supply, a rubber bulb is mainly installed inside. How does such a system work? As long as there is only air inside, the pressure inside is standard - the one set at the factory (1.5 atm) or which you set yourself. The pump turns on, starts pumping water into the tank, the pear begins to grow in size. Water gradually fills an increasing volume, more and more compressing the air that is between the tank wall and the membrane. When a certain pressure is reached (usually for one-story houses this is 2.8 - 3 atm) the pump is turned off, the pressure in the system stabilizes. When you open a tap or other flow of water, it comes from the accumulator. It flows until the pressure in the tank drops below a certain level (usually about 1.6-1.8 atm). Then the pump turns on, the cycle repeats again.

If the flow rate is large and constant - you are taking a bath, for example - the pump pumps water in transit, without pumping it into the tank. The tank begins to fill after all the taps are closed.

The water pressure switch is responsible for turning the pump on and off at a certain pressure. In most accumulator piping schemes, this device is present - such a system works in optimal mode. We will consider connecting the accumulator a little lower, but for now let's talk about the tank itself and its parameters.

Large volume tanks

The internal structure of accumulators with a volume of 100 liters and above is slightly different. The pear is different - it is attached to the body both above and below. With this structure, it becomes possible to deal with the air that is present in the water. To do this, there is an outlet in the upper part, into which a valve for automatic air release can be connected.

How to choose tank volume

You can choose the volume of the tank arbitrarily. There are no requirements or restrictions. The larger the tank, the more water you will have in case of a shutdown and the less often the pump will turn on.

When choosing a volume, it is worth remembering that the volume that is in the passport is the size of the entire container. Water in it will be almost half less. The second thing to keep in mind is dimensions containers. A 100 liter tank is a decent barrel - about 850 mm high and 450 mm in diameter. For her and the strapping, it will be necessary to find a place somewhere. Somewhere - this is in the room where the pipe comes from the pump. This is where most of the equipment is installed.

If you need at least some guidelines to choose the volume of the accumulator, calculate the average flow rate from each draw-off point (there are special tables or you can see it in the passport for household appliances). Sum all these data. Get possible consumption in the event that all consumers will work simultaneously. Then estimate how many and which devices can work simultaneously, count how many in this case per minute the water will go away. Most likely by this time you will already come to some kind of decision.

To make it a little easier, let's say that the volume of the hydraulic tank of 25 liters is enough to meet the needs of two people. It will ensure the normal functioning of the small system: faucet, sink and small . If there is another household appliances capacity needs to be increased. The good news is that if you decide that the existing tank is not enough for you, you can always install an additional one.

What should be the pressure in the accumulator

In one part of the hydraulic accumulator is compressed air, water is pumped into the second. The air in the tank is under pressure - factory settings - 1.5 atm. This pressure does not depend on volume - and on a tank with a capacity of 24 liters and 150 liters it is the same. More or less may be the maximum allowable maximum pressure, but it does not depend on the volume, but on the membrane and is indicated in the technical specifications.

Pre-check and pressure correction

Before connecting the accumulator to the system, it is advisable to check the pressure in it. The settings of the pressure switch depend on this indicator, and during transportation and storage the pressure could drop, so control is very desirable. You can control the pressure in the gyro tank using a pressure gauge connected to a special inlet in the upper part of the tank (capacity of 100 liters or more) or installed in its lower part as one of the piping parts. Temporarily, for control, you can connect a car pressure gauge. His error is usually small and it is convenient for him to work. If this is not the case, you can use the regular one for water pipes, but they usually do not differ in accuracy.

If necessary, the pressure in the accumulator can be increased or decreased. To do this, there is a nipple at the top of the tank. A car or bicycle pump is connected through the nipple and, if necessary, the pressure is increased. If it needs to be bled off, the nipple valve is bent with some thin object, releasing air.

What air pressure should be

So the pressure in the accumulator should be the same? For normal operation household appliances need a pressure of 1.4-2.8 atm. To prevent the tank membrane from tearing, the pressure in the system should be slightly higher than the tank pressure - by 0.1-0.2 atm. If the pressure in the tank is 1.5 atm, then the pressure in the system should not be lower than 1.6 atm. This value is set on the water pressure switch, which is paired with a hydraulic accumulator. These are the optimal settings for a small one-story house.

If the house is two-story, you will have to increase the pressure. There is a formula for calculating the pressure in a hydraulic tank:

Vatm.=(Hmax+6)/10

Where Hmax is the height of the highest draw point. Most often it is a shower. You measure (calculate) at what height relative to the accumulator its watering can is, substitute it into the formula, you get the pressure that should be in the tank.

If the house has a jacuzzi, everything is more complicated. You will have to select empirically - by changing the relay settings and observing the operation of the water points and household appliances. But at the same time, the working pressure should not be more than the maximum allowable for other household appliances and plumbing fixtures (indicated in the technical specifications).

How to choose

The main working body of the hydraulic tank is the membrane. Its service life depends on the quality of the material. The best for today are membranes made of isobutyl rubber (it is also called food grade). The body material matters only in membrane type tanks. In those in which a "pear" is installed, water contacts only with rubber and the material of the case does not matter.

The flange should be made of thick galvanized steel, but stainless steel is better

What is really important in tanks with "pears" is the flange. Usually it is made of galvanized metal. In this case, the thickness of the metal is important. If it is only 1 mm, after about a year and a half of operation, a hole will appear in the metal of the flange, the tank will lose its tightness and the system will stop working. Moreover, the guarantee is only a year, although the declared service life is 10-15 years. Flange deteriorate usually after finishing warranty period. There is no way to brew it - very thin metal. You have to search in service centers new flange or buy a new tank.

So, if you want the accumulator to serve for a long time, look for a flange made of thick galvanized steel or thin, but made of stainless steel.

Connecting the accumulator to the system

Typically, the water supply system of a private house consists of:

In this scheme, a pressure gauge may also be present - for operational control pressure, but this device is not required. It can be periodically connected - for test measurements.

With or without 5-pin fitting

If the pump is of a surface type, the accumulator is usually placed near it. In this case check valve put on the suction pipeline, and all other devices are installed in one bundle. They are usually connected using a five-pin fitting.

It has leads with different diameters, just for the devices used for tying the accumulator. Therefore, the system is most often assembled on its basis. But this element is not at all necessary and everything can be connected using ordinary fittings and pipe pieces, but this is a more time-consuming task, and there will be more connections.

How to connect a hydraulic accumulator to a well - a diagram without a five-pin fitting

With one of its inch outlets, the fitting is screwed onto the tank - the branch pipe is located at the bottom. A pressure switch and pressure gauge are connected to the 1/4 inch outlets. A pipe from the pump and wiring to consumers are connected to the remaining free inch outlets. That's all the connection of the gyroaccumulator to the pump. If you are collecting a water supply scheme with surface pump, you can use flexible hose in a metal winding (with inch fittings) - it is easier to work with it.

A visual diagram of the connection of the pump and accumulator - where necessary, use hoses or pipes

As usual, there are several options, you choose.

Connect the accumulator to the submersible pump in the same way. The whole difference is where the pump is installed and where to supply power, but this has nothing to do with installing a hydraulic accumulator. He puts it in the place where the pipes from the pump go. Connection - one to one (see diagram).

How to install two hydraulic tanks on one pump

When operating the system, sometimes the owners come to the conclusion that the available volume of the accumulator is not enough for them. In this case, a second (third, fourth, etc.) hydraulic tank of any volume can be installed in parallel.

There is no need to reconfigure the system, the relay will monitor the pressure in the tank on which it is installed, and the viability of such a system is much higher. After all, if the first accumulator is damaged, the second one will work. There is one more positive moment- two tanks of 50 liters each cost less than one of 100. The point is more sophisticated technology production of large containers. So it's also more cost effective.

How to connect a second accumulator to the system? Screw a tee onto the input of the first one, connect the input from the pump (five-pin fitting) to one free output, and the second container to the remaining free output. All. You can test the circuit.

The heating system of a private house (as well as water supply) must be functional and reliable. If during installation any violations were made or something was not done, then it will not last long, even if it works for some time. One of the main elements in any autonomous system related to the use of water is an expansion tank for water supply, the selection, installation, installation of which will be discussed in this material.

What is it?

Even the name itself speaks for itself - an expansion tank is needed to expand the entire heating circuit of the house or water supply pipes through which hot or cold water flows. The fact is that during heating, the liquid increases in volume, and the pipes through which it flows do not change their physical parameters - their elasticity tends to absolute zero. This means that the pressure inside the pipes and the entire installation will increase, which can lead to damage - so-called water hammers occur, and as a result of them - destruction individual elements installations or circuits from pipes. This applies mainly to the heating system, but it also fully relates to hot water supply.

To avoid water hammer, the engineers came up with the idea to include in the system a small reservoir filled with air, that is, the substance that, unlike water, is compressed. And if the pressure in the pipes increases during the heating of the water, then thanks to this tank it will increase very slightly. "P , you can read in our article".

On a note! Expansion tank often installed in other systems, but the purpose of its use is the same - to reduce pressure in pipelines and the risk of air locks.

Another such tank is sometimes used to create a reserve supply of cold water and provides liquid supply to any place in the system in a matter of minutes. At the same time, the average volume of the container is about 30 liters.

For a system that provides a house with water, tanks equipped with membranes are most often used. This is a relatively small container, inside which there is a diaphragm made of an elastic material and dividing the device into two parts - with air and airless, or rather, water. When the water supply system is operating, the water chamber is filled with liquid and, acting on the membrane, compresses it, reducing the volume of the air part, increasing the pressure in it. As soon as the pressure reaches a certain level, the pump that pumps water will stop. And its inclusion occurs when the pressure drops to minimum values.

On a note! The pressure inside the system allows you to monitor the pressure gauge installed in it.

Such a tank allows you to ensure the uninterrupted operation of the water supply system and a steady flow of water in any house, even in a multi-storey one.

Types of tanks

Expansion tanks are of two types - closed and open. They differ from each other in design features.

Table. Types of expansion tanks.

Membrane tanks, in turn, are divided into two types - with a replaceable diaphragm and with a stationary one. The replaceable membrane speaks for itself - if necessary, it can be easily changed by removing it through a flange fixed with a few bolts. An expansion tank of this type serves as long as possible, and the shape of the body can be both vertical and horizontal, which makes it possible to select a container for a specific room.

Attention! In large expansion tanks, the membrane is additionally fixed with a nipple.

In containers with a stationary membrane, this part cannot be replaced - it is tightly attached to the walls of the housing. In case of failure of the unit, it is completely changed. By the way, water in such an installation, unlike the previous type, is in contact with the metal of the tank, as a result of which a corrosion process occurs on its inner surface. Installation can also be both vertically and horizontally oriented.

Expansion tanks are not only mounted, but also floor. They may also have flat shape, differ in color: blue are for cold water, red for hot.

Popular Models

Now on the market there is a huge range of different expansion tanks from various manufacturers. Models differ from each other in quality, size, shape and even color, although they are similar in principle to each other. Choosing a tank for a specific water supply system will not be difficult. You should pay attention to the models of tanks from the following companies - Russian "Dzhileks" and Italian Elbi, Aquasystem, as well as Refix (Reflex), Zilmet. , you can read in our article.

The advantages of Gileks tanks are the complete absence of the risk of air jams in the system and the absence of water-air contact, due to which liquid evaporation is excluded, and rust does not damage the pipes. The brand produces tanks of various sizes - from 6 to 700 liters. The disadvantage of containers is that only installations with a volume of more than 24 liters have removable membranes. By the way, the diaphragm is made of high-quality EPDM - ethylene-propylene-diene-rubber. Tanks "Dzhileks" are economical, durable, inexpensive, but at the same time reliable and can have different shape.

Elbi tanks have it all Required documents, including a certificate of conformity and a sanitary and epidemiological conclusion, allowing you to safely use them in residential buildings. There are vertical, horizontal, and also for sanitary water. Vertical tanks belong to the AS / AC series and have interchangeable diaphragms, they can be of different volumes - from 5 to 25 liters - and are used in domestic water supply systems, as well as in irrigation systems and other installations that do not need powerful water pressure. The membranes inside the containers are made of EPDM, working temperature ranges from -10 to +99 degrees. The tank is protected from corrosion by resistant paint.

Bucky Elbi horizontal way units belong to the AFH series and have replaceable membranes. They have more capacity than the previous series - from 25 to 100 liters of water. Such installations can already be used in small industries. The tanks are made of durable steel and have a special platform for mounting the pump.

Refix tanks are suitable for use in both technical and drinking water systems and are excellent hydraulic accumulators. All parts that come into contact with water are protected from rust, and the liquid is perfectly stored inside the rubber bulbs. Models DD, DE are designed for water saving applications in drinking water systems, ideal for use in environments with increased level rust formation. The tanks of the DE series have a bulb, which is only replaceable in models with a volume of more than 50 liters. The models of the HW series, designed for individual water supply systems, also have feet for installation on the floor and a place to mount the pump.

The international company Zilmet has been holding a high position in the equipment market for more than 50 years, and in Europe it is considered largest producer expansion tanks. Their Hydro-PRO devices are used to work with any water in various types installations. The equipment is made of durable and high-quality carbon steel, and special internal MIG welding is used in the production, thanks to which it is possible to avoid damage to butyl rubber membranes. The inside of the tanks are coated with high-strength powder resin, which prevents rust from prolonged contact with moisture. Operating temperature range - from -10 to +99 degrees.

Aquasystem tanks have replaceable membranes and come in various volumes - from 8 to 50 liters. The maximum coolant pressure is 0.5 MPa, and air - 0.15 MPa. The operating temperature range of the equipment varies from -10 degrees to +110. Tanks are made of black steel, painted powder paint.

Attention! Don't be fooled by cheapness! As you know, a miser pays twice. The fact is that the use of low-quality equipment can lead to serious damage not only to the expansion tank, but also to the system itself, and repair will cost much more than buying high-quality equipment right away.

With regard to the quality of the equipment, Special attention pay attention to the rubber from which the diaphragm is made. Good rubber is not only a guarantee of a long service life of the equipment, but also the safety of those who will use water from a water supply system equipped with a tank.

The choice of accumulator

When choosing an expansion tank, you should pay attention to its characteristics, the materials from which it is made. Be sure to evaluate the material from which the pear or diaphragm is made, its strength and quality, compliance with all hygienic and sanitary standards, allowable temperatures use. From right choice In accordance with the operating conditions, the durability of the work will also depend.

Important point when choosing equipment correct selection required capacity. This will prevent the number of pump starts in the system, which will extend its life. You can calculate the correct volume for the cold water supply system using the formula:

Vt = 16.5*(Qmax/a)*((Pmax*Pmin)/((Pmax – Pmin)*Pprec)),

• Qmax is the maximum water consumption (l / min.);
• a - the optimal frequency of switching on the equipment for 1 hour (varies from 10 to 15 and is indicated in the pump passport);
• Pmax and Pmin are values ​​​​(measured in bar) that show the pump on and off pressures (pressure switch settings);
• Pprec (bar) - an indicator of the initial pressure in the cavity with air inside the expansion tank (should not be more than Pmin; on the contrary, it is set 0.5 less than Pmin).

Note! When calculating according to this formula, 1 is added to all values. And the value of the tank volume Vt obtained by the formula is always rounded up.

For hot water supply systems, the volume is calculated differently:

V = 0.0221*C / (1-((Pi+1)/(Pf+1)),

• C is the total amount of water in the water heating system;
• 0.0221 - indicator thermal expansion, in the range of 10-60 degrees equal to this figure;
• Pi is the pre-injection pressure indicator of the expansion tank;
• Pf is the pressure indicator when the safety valve is bled.

The volume of water used, in turn, is affected by the number of people living in the house, the number of points of water use (faucets, washing machines etc.), the possibility of including several such points at once.

Attention! If you use a tank of the wrong size (with underestimated values), then soon, due to a heavy load, it will begin to leak. Fortunately, with an increase in the number of people living in the house, and hence the load on the equipment, you can install an additional tank without removing the already installed one.

and the volume of the expansion tank for the heating system

Autonomous water supply system for modern home- this is not new. Quality Devices for water supply tested by users and time.

But it is better for buyers to familiarize themselves with the functionality of all devices of an autonomous water supply system before purchase and installation.

Kinds

In order to properly pump water long time, a diaphragm expansion vessel is required.

For the convenience of the system and saving space, three types of these devices are on sale:

• floor;
• hinged;
• flat.

Specialist's note: when choosing between types of expansion tanks, remember that only the floor tank has a replaceable membrane.

Operating principle

Fluid pressure builds up in the system. Then storage tank filled with a certain volume.

In it, the water compartment gradually increases, and the opposite compartment containing air decreases.

This process occurs until equilibrium is obtained, in other words, the desired pressure in the system. When the pressure drops below the level of air pressure, timely contraction of the inner membrane occurs.

Due to it, the water supply is normalized. The tank device functions as long as necessary to stabilize the pressure of water and air.

The right choice of instrument

When choosing a model with the necessary functions and volume, consider the fact that the frequency of the pump depends on the total volume of the tank.

The leading characteristic for any tank is not the functionality, but its volume.

At the same time, for each water supply system there are criteria that cannot be neglected, namely:

1. Number of permanent water users. (Daily use).
2. Number of points for water intake. (Appliances, faucets and other plumbing fixtures).
3. Approximate frequency of use of water intake points at the same time.
4. On-off cycle. You need to know exactly the one-hour limit of this cycle for your pump.

Approximate calculation:

When calculating for three permanent consumers, a tank with a total volume of 20-24 liters is installed. However pump equipment should produce approximately 2 cubic meters per hour.

When counting on four regular users with a margin, it is better to install equipment from 50 liters. The pump capacity in this case is approximately 3.5-3.7 cubic meters per hour.

If there are more than 10 consumers, then a tank of at least 100 liters is required, and pumping equipment with a rate of more than 5 cubic meters per hour.

To avoid breakage and expensive repairs, you need to carefully read the manufacturer.

In this choice, chasing a cheaper and dubious brand is not necessary. Incorrect savings can lead to breakdowns in the future.

Models with a low retail price inside are made, as a rule, without defects. But consumables are always made from the cheapest materials.

It is better to ask about the material from which the membrane is made. Its environmental friendliness and stability will improve comfort as well as the life of the system.

You may also be interested in the article about.

Read the article on malfunctions and repair of the hydraulic accumulator with your own hands.

How is it different from a hydraulic accumulator

Installation diagram of a membrane expansion tank Accumulator, membrane tanks and are devices that are most in demand in modern device plumbing and heating.

But it is better to know their significant differences, because the expansion tank creates the effect of pressure smoothing when the liquid is heated.

talking plain language, if not the right space for water that gradually changes its volume, then any non-plastic container will burst. For this, a device with a membrane was created, which normalizes the difference in a working system.

Both devices are appearance very similar. But their device, purpose and performance characteristics various.

The hydraulic accumulator is used to supply water for drinking.

Its main property is the supply of the desired water pressure.

The most important part in the tank and accumulator is the membrane.

The material from which it is made is different in devices for supplying water, including between the tank and the accumulator.

The arrangement of the chambers for air and liquid is also different. The accumulator inside is equipped with a “pear” tank. Air exerts pressure on it, it is between the walls of the tank and the water tank.

For each of the above devices, the most important parameter is the durability and reliability of the membrane. Its quality guarantees the stability of the entire system.

Watch the video in which the specialist explains how to choose a membrane expansion tank for home water supply:

A membrane tank is needed for protection engineering system from water hammer and full ensuring its high-quality work. After purchasing equipment, you need to carefully consider , how to install a membrane tank so that it works without failures. The hydraulic accumulator in the water supply performs several functions: it accumulates a supply of water, maintains in the system required pressure, serves as a reserve to reduce the frequency of switching on and off the pump.

Without installing a diaphragm tank, the life of the pump is significantly reduced. In a system provided with a hydraulic accumulator, water can be collected even when the electricity is turned off. During the first start of the pump, the water chamber of the tank is filled with water. The larger the volume of water in the tank, the smaller the air volume and the higher the pressure. Having reached the set pressure indicator, which is necessary to turn off the pump, it automatically turns off. As soon as the pressure in the system drops to acceptable level, the water supply will turn on immediately. A pressure gauge is installed on the accumulator to check the pressure. It is also necessary to set the required range of operation of the equipment.

Before you start connecting the accumulator to the water supply system, you should:

• Carefully study the instructions supplied with the equipment.
• Conduct technical calculations pressure and compare with those specified in the standard operating manual.
• To carry out the installation with high quality, you need a key for detachable connections and plastic pipes, right size wrench.
• Special brackets will be needed to mount large volume equipment.

Measurements and calculations of the operated equipment should be carried out by a highly qualified specialist. The quality of the water supply system depends on the accuracy of the calculations and measurements performed.

Many years of experience in the use of membrane tanks for water supply has shown that horizontal models are the best option. If you have connected submersible pump, purchase and install vertical hydraulic accumulators.

1. The tank must be installed in an accessible Maintenance place.
2. During installation, it is necessary to provide for the possibility of dismantling the pipes of the system, if necessary.
3. The diameters of the pipeline and the connecting pipe must match.
4. Be sure to install a pressure gauge to monitor system pressure.
5. It is also necessary to calculate and install shut-off valves.

Elements affecting the hydraulic resistance must not be connected between the pump and the accumulator.

Mount the membrane tank only at positive temperatures. For ease of pressure control, the air valve is installed in an accessible area. The same rule applies to connection. drain cock, shield and both types of fittings.

To avoid unnecessary stress on the unit, the pressure reducer should be mounted after connecting the measuring meter. Safety valve should be mounted in front of the flow pipe.

Two installed in the system shut-off valves on both sides of the tank will help to avoid unforeseen situations. Install a drain valve in front of the accumulator.

Setting the operation of the membrane tank

When installation work carried out according to the recommendations, it is necessary to adjust the operation of the mechanism:

1. When pumping air, choose the right pressure indicated by the manometer.
2. Turn on the water supply pump.
3. Equalize the pressure and float the membrane.
4. Setup completed. Now the water supply system with the installed membrane tank is ready for operation.

If you purchased a tank with a removable membrane, after a while it can be replaced. For installation new membrane first unscrew the bolts on the flange connection, and then remove the flange and the obsolete membrane. Install a new one and tighten everything carefully again.

Mounting errors to avoid

• Do not use seals that are not designed for such work. They very often lead to water leakage.
• The location of the tank must be chosen correctly.
• Inconsistency of the volume of the tank with the water supply system.
• The wrong tools for the job.
• The membrane tank must not be opened or drilled with force.

Why do you need a membrane tank for water supply? When organizing an autonomous water supply for a private house from wells or wells, it is necessary to create an emergency supply of water. An expansion tank for water supply is perfect for these purposes. These containers are practical, have a large volume, but to ensure a normal operating mode, it is necessary to use a number of devices, and not be limited to just one installation. When a tank is included in the water supply system, the autonomy of water supply is significantly increased. The created reserve will allow solving problems with water supply that may arise in the event of pump breakdowns and during maintenance of equipment and the well. On the this moment The industry produces a huge number of different models, which greatly complicates the choice.

When a tank is included in the water supply system, the autonomy of water supply is significantly increased.

Description, construction types

An expansion tank for water supply is used to maintain the desired pressure level in autonomous water supply. Most often, membrane (expansion tanks) are used for these purposes. These are containers, inside of which there are rubber membranes that divide the tank into chambers. One chamber is water, the other is air.

The tank is connected to the water supply of an autonomous water supply system so that the inlet branch supplies water to the tank, filling it, and only after filling a certain volume, water is supplied to consumers.

The principle of operation is as follows: when the system is turned on (started), the pump pumps water into the water chamber until it is filled. In this case, the volume of the second chamber is significantly reduced. When the air chamber contracts, the volume of air inside it does not change, so the pressure on the membrane increases. Accordingly, the pressure in the system increases.

Expansion tanks use a membrane that separates it into 2 reservoirs, one with air and the other with liquid. In this case, it is necessary to have pressure control equipment (pressure switch) in the tank. This is necessary to automatically turn off the pump, the same sensor automatically starts the pump when the pressure in the tank drops below the programmed value. This will allow automatic operation the entire water supply system.

To control the pressure, it is also necessary to install a separate pressure gauge, which will duplicate the pressure switch in case it breaks. At the same time, it is important to carefully and accurately adjust the pressure sensor, since the pressure in the water supply system depends on its operation. The installation of expansion (membrane) tanks in an autonomous water supply system solves several issues at once:

1. Maintaining pressure in the system when the pump is turned off and if it is stopped for service or repair. In addition, such tanks can significantly reduce the power of the water supply pump.
2. Protection of the water supply system from water hammer, which may occur due to voltage drops in electrical networks, which significantly increases the survivability of the system.
3. Protects against pressure drops and other unpleasant nuances associated with air entering the system (for example, when the water level in the well drops).
4. In the event of an unexpected shutdown, the pump will maintain some pressure in the system.
5. Reduces wear and tear of pumping equipment, thereby extending its life. This is due to the fact that the pump pumps water only after the water pressure in the tank decreases, and not after the water pressure in the system decreases.
6. In the case of low water consumption, it allows not to turn on the pumping equipment at all, but to use only the water that is in the tank.

Membrane tanks are different design. At the moment, there are only 2 types:

1. With replaceable membrane. Its main advantage is the ability to replace the membrane when it is worn or broken. For replacement, a flange is provided through which the old membrane is removed and a new one is laid. The flange is bolted to the tank body. If the tank has a large volume, additional membrane fastenings are possible. Often back membranes are attached to the nipple. Therefore, for extraction, it is necessary to dismantle the nipple, otherwise the membrane can be torn.
2. A feature of the functioning of such a device is the absence of contact of water with the tank. Because the water stays inside the membrane. This protects the metal body from rust, water is not contaminated when it comes into contact with the surface. Thus, the service life of such tanks is significantly extended. Devices with similar designs are available in vertical and horizontal versions. The main disadvantage is the increased wear of the membrane (which requires it frequent replacement) and the need to carefully control chemical composition the membrane itself to prevent toxic substances from entering the system (therefore, you can’t buy cheap Chinese or Polish membranes!).
3. Having a stationary diaphragm. They have a statically fixed membrane (diaphragm), which divides the tank into 2 parts. The main difference is the impossibility of replacing the diaphragm in case of its breakthrough or wear during operation. Similarly to the previous design, air will be in one compartment, water in the other. In this case, the water has direct contact with the tank body. If metal is used as a housing, it may rust and the system may be clogged with rust. Therefore, to prevent rust internal surfaces such tanks are painted with special paint. It is worth noting that over time the paint is washed off, this leads to contact of the metal with water.

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Device selection

The main criterion for choosing such a tank is the maximum allowable volume of water that can accumulate in the tank. To select a tank by volume, it is necessary to take into account a number of parameters: the number of people living in the house, the number of water consumers (toilets, water intake points, valves, Appliances etc.). In this case, it is necessary to calculate the pressure drop, which can be with the simultaneous opening of all water intake points.

The criterion is the number of system starts per hour (taking into account the possibility of start-stop cycles for the pump).

So, for a private house in which 3 people live, with a pump of 2 m³ / h, a tank with a volume of about 25 liters is selected. If 4-5 people live in the house, a tank with a volume of about 50 liters is selected with a pump of 4 m³ / hour. Further, with an increase in the number of consumers, the required minimum volume of the tank and the need for frequent switching on increase significantly. pumping station. However, it is worth remembering that a smaller volume allows you to reduce pressure drops in the system. At the same time, the tank itself is a reserve tank for storing water.

An important criterion is the choice of tank manufacturers. It is worth excluding cheap models from Poland and China in advance, since very often they use materials of poor quality and dangerous to human health. At the same time, attention should be paid to the quality of the rubber membrane or diaphragm.

The next criterion is the cost of the membrane. This is relevant only for tanks with a replaceable membrane. The fact is that manufacturers significantly overestimate the cost of consumable (spare) materials, often unreasonably. Therefore, it is recommended to select models that allow the installation of membranes from other manufacturers.