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Membrane expansion tanks have found application as pressure compensators in the water supply system.
Currently, heat supply, where water moves under the influence of gravity, is being replaced by communications with forced movement of the coolant.
A compensating device will be required when installing an autonomous water supply or when distributing hot water.
A large number of models complicates the choice, which is made on the basis of knowledge of the principles of operation, specifications devices and communications.
Design features
Despite the small design differences in the models used in water supply and heating, the devices operate according to the same physical principle.
In general, tank design consists of a sealed steel body and a rubber membrane.
"Pears" are divided into two types:
- a diaphragm that divides the container in half;
- rubber container attached to the inlet pipe.
IMPORTANT!
Models of the first type do not have the ability to replace the membrane. In case of malfunction, change the device.
Bulb replacement is easy. To do this, it is necessary to unwind the flange of the inlet (it is written about devices for fastening plumbing fittings and pipelines).
The heating system uses models in which the coolant is in contact with metal case.
Devices for water supply isolate water from steel walls. Such models are recommended as small ones.
The contact of the liquid with the body metal is the difference in the two types of tanks.
When the temperature drops or a decrease in water pressure in the "pear" air pushes the liquid into the pipeline.
Right choice
Arriving at the store, remember that expanders are divided according to their use in heating or water supply.
Often, distinguish models externally, impossible, the device is even painted in one color, usually red.
Differences in membrane properties can lead to accidents if you install a model that does not match the specifications.
Pay attention to features device indicated on the nameplate.
The label contains information about the characteristics of the device.
If it is indicated that the pressure is 10 bar, the temperature is +70 degrees, then the model is intended for pipelines with cold water.
The inscription on the plate: temperature +120 degrees, 3 bar - such a device must be installed for heating.
The next thing to pay attention to is the volume of the steel tank, which is defined as follows:
IMPORTANT! An expander is installed for the boiler, used in cold water supply.
Mounting the device
Proper installation of the expander will affect the operation of communications and the service life of the device itself.
First of all, fix the tank on the wall or floor in the position indicated in the manufacturer's instructions.
The next step is to install shutoff valves at the point where the tank is connected to the line (you may need it).
This will help to carry out maintenance, repair or replacement. membrane tank.
Water from the expander is drained through a special fitting, which is installed in the gap between the tank and the fittings.
This will drain the liquid before dismantling the device (the price of a cutting screw pipe thread indicated).
For heating systems
If the manufacturer did not indicate the orientation of the expander, then the device is fixed with the inlet down.
The vertical position allows you to continue working if the membrane is damaged. Air located on top will continue to press on the liquid without entering the pipeline.
Tank installation is possible both on the forward branch and on the return line. This applies to heating based on gas or liquid boilers.
In systems with solid fuel boilers the expander is installed on the return line. The setting is carried out using the spool located on top.
After the installation of the membrane tank, the system is filled with coolant, periodically bleeding air.
It is necessary to measure the water pressure at the outlet of the boiler and compare it with the pressure in the expander.
Tank parameters should be 0.2-0.3 bar lower than in a pipeline.
For larger and smaller values, air is pumped in or bled through the spool.
For plumbing
oriented in the room, depending on the convenience of the location.
Orientation of the nozzle down doesn't matter.
A drain device and shut-off valves are installed in front of the storage tank in the form ball valve ().
Extender for cold water configured differently than for heating.
The pressure in the system is created by the pump, for which I set the threshold for switching on and off (it is written about the repair of the pressure switch of the pumping station with my own hands).
Based on the characteristics of the pump, the pressure in the tank is set to 0.2 bar lower than the threshold of the pumping equipment.
This will avoid the possibility of water hammer..
When installing the tank on the hot water line, the pressure is set to 0.2 bar higher than the upper threshold of the station. This value will allow water not to stagnate in the pipes.
Finally
A seemingly simple design will require knowledge, experience and accuracy during installation. The expander plays a significant role in pipelines of an autonomous, closed type.
The service life of the tank and communications as a whole depends on the quality of the installation.
It is worth remembering that a competent approach is necessary when installing any element of plumbing or heating.
Why you need a membrane tank in the autonomous water supply system of a private house, you will find out while watching the video.
Today we have to find out why we need to install an expansion tank in the water supply system, how the membrane tank works, and how to connect it correctly. We will start, however, by clarifying the wording and names of sanitary fittings.
Down with the confusion
In plumbing stores, you can find two varieties of these devices that differ from each other in color:
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1. Expansion tanks installed for heating - water supply are usually red and, in full accordance with the name, are designed to compensate for the thermal expansion of water or liquid heat carrier when heated. Liquids are practically incompressible, and when they expand, the pressure in closed circuit begins to grow at a catastrophic rate; air cushion inhibits its growth. |
 Hydraulic accumulators, or expansion tanks for drinking water systems - blue |
2. Hydraulic accumulators - of blue color(cm. ) . They allow you to create an autonomous supply of cold water, and act as a damper. That is, they extinguish pressure surges when opening / closing valves and turning on / off the pump supplying water. |
The video in this article will help you learn more about membrane tanks.
Device
How are expansion tanks for water supply arranged?
A membrane tank is a steel container with a pipe for connecting to a water supply or heating system and a valve for pumping. It is divided by an elastic membrane into two compartments - air and water. The air compartment is often filled with nitrogen instead of air, which prevents corrosion of the tank walls.
Curiously: the expansion tank of a hot water or heating system is usually equipped with a membrane with increased heat resistance. There are no other design differences between it and the accumulator, so the expansion tank can be safely used as a hydraulic accumulator.
Scheme
Now let's take a closer look at why an expansion tank is needed in the water supply system, using specific schemes as an example.
Boiler piping
The boiler piping usually includes two fittings installed on its inlet pipe:
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Check valve. It lets cold water from the tap in storage water heater, but does not allow it to pour back when the cold water is turned off. |
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Safety valve. Because the check valve turns the water supply and boiler into a closed circuit, when the water is heated, the pressure in it begins to rise rapidly. When it reaches dangerous values, the safety valve discharges excess water through the drain tube. |
Useful: Check and safety valves combined in one housing are often sold under the name "boiler safety group".
While the volume of the boiler is small, the loss of heated water is insignificant or absent (thermal expansion is compensated by the elasticity of the walls of the water pipe). But with its significant volume hot water is discharged into the drainage in liters and tens of liters, which significantly affects the costs for the needs of hot water supply.
Connecting the expansion tank to the water supply system completely eliminates the loss of heated water. Its excess is accommodated by a membrane tank, which is accompanied by a slight increase in pressure in the circuit.
How big should an expansion tank be for a water supply system with a known volume boiler?
Usually it is taken equal to 10% of the volume of the boiler. Yes, the thermal expansion of water within reasonable temperature limits is less than 10%; however, do not forget that the capacity of the water compartment is not equal to the full volume of the membrane tank: part of this volume is occupied by air.
Therefore, in practice, rounding up is used: an expansion tank for water supply of 50 liters is able to provide safe work 500 liter boiler.
Water supply
How to use a hydraulic accumulator or expansion tank for cold water supply, providing yourself with water during its periodic shutdowns?
Do-it-yourself installation instructions for the device are extremely simple and consist of only two points:
- Connect the tank pipe to any part of the water supply with a flexible or rigid connection;
- Install a non-return valve at the cold water inlet. It will not allow water to drain from the tank into the disconnected and dumped main water supply.
Please note: the useful capacity of the membrane tank differs markedly from its full volume. For example, an expansion tank of a water supply system of 500 liters is able to store no more than 250 liters of water in case of a shutdown.
Well water
How to install an expansion tank in a water supply system with water supply from a well or well? Again, it is mounted at any point of the water supply.
In addition to the membrane tank, such a system includes:
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Submersible or It raises water and creates an excess pressure that ensures the operation of plumbing fixtures. |
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Check valve. It is placed after submersible pump or at the suction pipe of a surface pumping station. |
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An automatic relay that controls the operation of the pump (that is, turns it on when the pressure in the circuit drops and turns it off when the pressure reaches the upper critical value. |
What pressure should be maintained in the expansion tank of the water supply system?
The answer cannot be given without knowing the settings of the automatic control of the pump. The pressure in the expansion tank of the water supply should be slightly lower (by about 0.2 atmospheres) than the pressure for turning on the pumping of water from the well. In this case, the pump will start before the remaining water from the membrane tank flows out through the open tap.
How to pump up an expansion tank in the water supply system if the pressure in it has fallen below the required level? This can be done by anyone air pump- bicycle, automobile, etc. The pump hose is connected to the spool on the diaphragm tank.
Water from a container
Water supply from a storage tank is practiced in garden partnerships with scheduled water supply, as well as where worn-out water supply lines are often turned off for repairs. The easiest way to supply water to the water supply is by gravity, from a tank installed in the attic.
However, this scheme has three serious drawbacks:
- The water supply is limited by the strength of the overlap;
- The attic must be insulated and heated, otherwise the water will freeze in the very first frost;
- The pressure in a gravity water pipeline is limited by the vertical distance between the tank and the faucet. Meanwhile for normal operation household appliances (instantaneous water heaters, washing and dishwashers) you need a pressure of at least 3 meters (0.3 kgf / cm2).
Water supply from a tank installed in the basement, subfloor or ground floor, with the help of a pumping station, it is devoid of all these disadvantages: the weight of the tank standing on the surface or the screed is not limited by anything, the pressure is created by the pump, and the temperature of the soil is below the freezing level all year round above zero.
What role does the expansion tank for water supply systems play in this scheme? The same as when supplying water from a well: it smooths out pressure surges and allows the pump to stand idle with little water flow.
What should be the connection diagram for the expansion tank for water supply? Again, the same as with autonomous water supply from a well or well.
However: in practice, the water supply from the tank is usually supplied with a surface pumping station, which is a pump, an automatic relay with a pressure sensor and a hydraulic accumulator on one frame.
The fight against water hammer
A water hammer is a short-term pressure surge that occurs in a closed circuit due to the inertia of a moving water flow when it stops instantly. Water hammer often takes pressure beyond the strength of pipes and flexible hoses; the consequences are very predictable - the owner gets breaks in the water supply at the seams and fittings.
If expansion tanks are connected to the water supply, the water supply is made absolutely safe: the air tank in this case also plays the role of a damper. A small volume tank is mounted on the water supply inlet or (when collector wiring water) on the collector.
Conclusion
We hope that our material will help the dear reader in the design and installation of their own water supply. Good luck!
Used in cold water supply systems when water is supplied to the house from an external source.
Proper selection, installation and operation of tanks will ensure the safe operation of systems and reduce the likelihood of emergencies.
Membrane tanks VALTEC for heating systems
Purpose of the VALTEC expansion tank
The main task of a membrane expansion tank in a heating system is to compensate for an increase in the volume of water due to its thermal expansion.
In the absence of closed system tanks where excess coolant can flow, even a slight increase in temperature will lead to an increase in pressure, which may exceed the maximum allowable value for the elements of the hydraulic system.How the VALTEC expansion tank works
There is a diaphragm in the expansion membrane tank, which divides it into two parts, one of which contains nitrogen under initial overpressure, and the other part receives excess coolant from the system.
Initially, the entire volume of the expansion tank is completely occupied by nitrogen; when the coolant is heated, its volume increases, which leads to nitrogen compression. The pressure of the nitrogen cushion increases and equalizes with the pressure in the heating system at this static level. When the temperature of the coolant and, accordingly, its volume decreases, the pressure of the nitrogen cushion returns the coolant back into the system, preventing the pressure in the system from dropping below the set level.
Place of connection of the expansion membrane tank VALTEC to the heating systemThe pressure at the point of connection of the membrane tank to the system is always equal to the static pressure at this point at given temperature parameters.
Thus, the operation parameters of all other elements of the heating system, the required initial pressure in the expansion tank and the volume of the tank itself depend on the location of the expansion tank. On fig. 1 shows several options for connecting a membrane tank to a heating system with the following height parameters:- excess of the upper point of the system over the lower one (H) - 10 m;
- the heat generator and the safety valve are located 2 m above the lowest point of the system (h 1);
- the expansion tank is placed 1 m above the point of its connection to the system (h 2);
- static pressure at the level of the lowest point of the system - 15 m of water. Art.
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Rice. 1. Options for connecting a membrane tank to a heating system
The remote flags in Fig. 1 indicates the calculated values of the working pressure at the characteristic points of each system (in m of water. St).
The setting value of the safety valve is assumed to be 33 m of water. Art., pump pressure - 6 m of water. Art., system capacity - 200 l. The difference between the maximum and minimum coolant temperatures is 80 ºС.
In table. 1 shows the design characteristics of membrane tanks for circuits with their different connections.
Table 1. Calculated data for the systems of Figure 1
Selection of a membrane expansion tank VALTEC
A sufficient volume of the membrane expansion tank is recommended to be determined by the formula:
V b \u003d C β t / (1 - P a min / P a max), (1)
where C is the total volume of coolant in the heating system, l. Includes the volume of water in pipes, boiler, radiators and other elements of the system. This indicator is calculated by the actual capacity of each element of the system; P a min - initial (setting) absolute pressure in the expansion tank, bar ; P a max - the maximum absolute pressure possible in the expansion tank, bar.
With a certain error, the value of the coolant volume in the system can be selected from Table. 2. When calculating at the stage of a feasibility study, it is allowed to take the specific capacity of the heating system as 15 l/kW.
The values of the coefficient of thermal expansion of the coolant β t, corresponding to the maximum difference in water temperatures in the idle and operating system, are recommended to be taken from Table. 3.
The set absolute pressure is calculated using the formula:
P a min \u003d P a 0 + P st max - 0.1 (H B + h 2 + 1), (2)
where P a 0 - atmospheric pressure, bar; P st max - static pressure at the level of the lowest point of the system, bar; N B - excess of the tank tie-in point above the lower point of the system, m; h 2 - excess of the center of the tank above the tie-in point, m.
When the tank is located below the tie-in point, h 2 is substituted with a minus sign.
Absolute maximum pressure possible in the expansion tank:
P a max \u003d P a 0 + P PC + P st B - P st PC - 0.1 h 2, (3)
where P PC is the pressure setting of the safety valve, bar; P st B - static pressure at the level of the safety valve installation, bar; P st PC - static pressure at the level of the tie-in into the membrane tank system, bar.
Table 2. Approximate volume of coolant in the system
Table 3. The value of the coefficient of thermal expansion of heat carriers β t
| Temperature, °C | Glycol content, % | |||||||
| 0 | 10 | 20 | 30 | 40 | 50 | 70 | 90 | |
| 0 | 0,0002 | 0,0032 | 0,0064 | 0,0096 | 0,0128 | 0,0160 | 0,0224 | 0,0288 |
| 10 | 0,0004 | 0,0034 | 0,0066 | 0,0098 | 0,0130 | 0,0162 | 0,0226 | 0,0290 |
| 20 | 0,0018 | 0,0048 | 0,0080 | 0,0112 | 0,0144 | 0,0176 | 0,0240 | 0,0304 |
| 30 | 0,0044 | 0,0074 | 0,0106 | 0,0138 | 0,0170 | 0,0202 | 0,0266 | 0,0330 |
| 40 | 0,0079 | 0,0109 | 0,0141 | 0,0173 | 0,0205 | 0,0237 | 0,0301 | 0,0365 |
| 50 | 0,0121 | 0,0151 | 0,0183 | 0,0215 | 0,0247 | 0,0279 | 0,0343 | 0,0407 |
| 60 | 0,0171 | 0,0201 | 0,0232 | 0,0263 | 0,0294 | 0,0325 | 0,0387 | 0,0449 |
| 70 | 0,0228 | 0,0258 | 0,0288 | 0,0318 | 0,0348 | 0,0378 | 0,0438 | 0,0498 |
| 80 | 0,0290 | 0,0320 | 0,0349 | 0,0378 | 0,0407 | 0,0436 | 0,0494 | 0,0552 |
| 90 | 0,0359 | 0,0389 | 0,0417 | 0,0445 | 0,0473 | 0,0501 | 0,0557 | 0,0613 |
| 100 | 0,0435 | 0,0465 | 0,0491 | 0.0517 | 0,0543 | 0,0569 | 0,0621 | 0,0673 |
| 110 | 0,0515 | 0,0545 | 0,0568 | 0,0591 | 0,0614 | 0,0637 | 0,0683 | 0,0729 |
| 120 | 0,0603 | 0,0633 | 0,0653 | 0,0673 | 0,0693 | 0,0713 | 0,0753 | 0,0793 |
As the analysis of formula 1 shows, optimal choice volume expansion membrane tank is directly related to correct setting safety valve (according to SP 41-101-95 "Design of heat points" this is an obligatory element for an expander). It is usually set to a pressure that exceeds the allowable pressure for the most vulnerable element of the system by 10% (taking into account the difference in the heights of the valve and the protected element). Therefore, for heating systems, it is recommended to use valves with the ability to adjust the setting pressure. In addition, the valve must necessarily have a device for forced opening ("undermining") to periodically check its performance and to avoid sticking of the spool. An example of such a valve is shown in Fig. 3. .jpg) Rice. 3. Safety valve VALTEC VT.1831 with the possibility of setting and forced "undermining" |
The set pressure of the tank must not be lower than the hydrostatic pressure at the level of the center of the tank by more than 1 m of water. Art. (0.1 bar). Otherwise, already in the process of filling the system, the useful volume of the tank will be filled with coolant, and during subsequent heating and expansion of the liquid, a smaller volume will be provided than necessary. In other words, if the setting (factory) pressure in the tank is 1.5 bar, then the system must be filled to a pressure at the level of the center of the tank that does not exceed 1.6 bar. If, according to the project, it is necessary to establish a higher hydrostatic pressure in the system, then for this, before installing the tank, it is necessary to increase the pressure in it using an air pump.
In two identical systems that differ only in the type of coolant, a larger expansion tank will be required in the system where an antifreeze coolant based on glycol (ethylene or propylene glycol) is used, because. the expansion coefficient of glycol solutions is slightly higher than that of water.Thus, when changing from a water system to a glycol system, it may be necessary to replace the tank with a larger one or install an additional expansion tank.
A signal that the system needs a larger tank is the frequent operation of the safety valve.
Examples of strapping with membrane tanks
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Rice. 4. Installation of an expansion tank in a system with one boiler: 1 - expansion tank; 2 - safety valve; 3- circulation pump; 4 - filter; 5 - check valve; 6 - shut-off valve; 7 - air vent
AT this case The expander is located on the return pipeline of the system, which makes it possible to operate it at a lower coolant temperature than if it were installed on the supply line. This solution allows you to extend the life of the device. Connecting a tank to the suction port of the pump prevents the pump from cavitation.
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Rice. 5. Installation of expansion tanks in a system with several boilers and automatic limitation minimum temperature water in the return pipeline (one tank is provided for each boiler): 1 - expansion tank; 2 - safety group (safety valve, pressure gauge, air vent); 3 - circulation pump; 4 - three-way mixing valve; 5 - check valve; 6 - shut-off valve; 7 - hydraulic arrow
In this scheme, one expander per boiler is provided. The capacity of each of them must be no less than the calculated capacity for the entire system, i.e. if, according to the calculation, it needs a tank with a capacity of 80 liters, then this should be the capacity of each of the installed devices. This is due to the fact that when operating at reduced power, when the burner of one of the boilers is turned off, the corresponding circulation pump is also turned off and the three-way valve. In this case, there is no water circulation through the switched off boiler, and the expansion tank installed on this boiler is isolated from the rest of the system. The expansomat remaining in operation must provide compensation for the expansion of the coolant in the entire volume of the system. This situation is also valid when using two-way valves that perform the function of blocking the boilers.
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Rice. 6. Installation of an expansion tank in a system with several boilers and automatic limitation of the minimum water temperature in the return pipeline (one expansion tank for the entire system): 1 - expansion tank; 2 - safety group (safety valve, pressure gauge, air vent); 3 - circulation pump; 4 - three-way mixing valve; 5 - check valve; 6 - shut-off valve; 7 - hydraulic arrow
Membrane tanks for hot water systems
The main difference between membrane tanks for water supply is that the water in them should not come into contact with the walls of the case, as is allowed in heating systems. Therefore, they always use a chamber-type membrane (in the form of a bag). In addition, increased requirements are imposed on the material of the membrane of tanks for water supply in terms of the admissibility of contact with food liquids.
The calculation of the membrane expansion tank for hot water is carried out according to formula 1. The volume of water in the system is calculated taking into account the water contained in the pipelines and the water heater or heat exchanger.
An example of installing a membrane tank for hot water is shown in fig. 7..jpg)
Rice. 7. Installing an expansion tank in the hot water supply system: 1 - expansion tank; 2 - safety valve; 3 - pump; 4 - filter; 5 - check valve; 6 - shut-off valve
Membrane tanks VALTEC for cold water systems (hydraulic accumulators)
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| brand | Volume, l | D, mm | H, mm | L, mm | Do | Dy2 |
| VAV 8 | 8 | 200 | 333 | 3/4 | ||
| VAV 12 | 12 | 280 | 323 | 3/4 | ||
| VAV 24 | 24 | 280 | 523 | 3/4 | ||
| VAV 50 | 50 | 365 | 683 | 3/4 | ||
| VAV 80 | 80 | 410 | 795 | 3/4 | ||
| VAV 100 | 100 | 495 | 809 | 3/4 | 3/4x1/2 | |
| VAV 150 | 150 | 495 | 1079 | 3/4 | 3/4x1/2 | |
| VAO 24 | 24 | 280 | 297 | 523 | 1 | |
| VAO 50 | 50 | 365 | 382 | 595 | 1 | |
| VAO 80 | 80 | 410 | 427 | 728 | 1 | |
| VAO 100 | 100 | 495 | 517 | 730 | 1 | 3/4x1/2 |
| VAO 150 | 150 | 495 | 517 | 1000 | 1 | 3/4x1/2 |
Nomenclature and dimensions tanks for heating
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| brand | Volume, l | D, mm | H, mm | Do |
| VRV8 | 8 | 200 | 333 | 3/4 |
| VRV 12 | 12 | 280 | 323 | 3/4 |
| VRV 18 | 18 | 280 | 423 | 3/4 |
| VRV 24 | 24 | 280 | 523 | 3/4 |
| VRV 35 | 35 | 365 | 473 | 3/4 |
| VRV 50 | 50 | 365 | 605 | 3/4 |
| VRV 80 | 80 | 410 | 735 | 3/4 |
| VRV 100 | 100 | 495 | 809 | 3/4 |
| VRV 150 | 150 | 495 | 1079 | 3/4 |
Regulatory requirements for membrane tanks
| Regulation requirement | Standard |
| 4.34. Expansion tanks must be cylindrical shape; for tanks with inside diameter hulls up to 500 mm should be accepted flat welded or elliptical bottoms, and with a diameter of more than 500 mm - elliptical. | SP 41-101-95 |
| 4.35. Expansion tanks must be equipped safety valves. | |
| 4.47. Safety devices must be designed and adjusted so that the pressure in the protected element does not exceed the design pressure by more than 10%, and at design pressure up to 0.5 MPa - by no more than 0.05 MPa. Calculation bandwidth safety devices must be produced in accordance with GOST 24570. | |
| 7.2.6.1. To compensate for the thermal expansion of the coolant in independent heating systems, expansion tanks should be provided. | SP 31-106-2002 |
| 7.2.6.2. In a water heating system with artificial induction of coolant circulation, open or closed expansion tanks located in the heat generator room can be used. It is recommended to use expansion tanks of diaphragm type with thermal insulation. | |
| 7.2.6.3. The required tank capacity is set depending on the volume of coolant in the heating system. | |
| 5.19. To receive excess water in the system when it is heated and to feed the heating system in the presence of leaks in autonomous boiler houses, it is recommended to provide diaphragm-type expansion tanks. | SP 41-104-2000 |
| 3.4. It is not allowed to use metal-polymer pipes for expansion, safety, overflow, signal pipelines. | SP 41-102-98 |
| 13.14. Water pressure and hydropneumatic tanks drinking water, as well as storage batteries should be made of metal with external and internal anti-corrosion protection; at the same time, materials approved by the Glavsanepidnadzor of Russia should be used for internal anticorrosion protection. For hot water storage tanks thermal insulation should be calculated. | SNiP 2.04.01-85* |
| 13.17. Hydropneumatic tanks must be equipped with supply, discharge and drain pipes, as well as safety valves, pressure gauge, level sensors and devices for replenishing and regulating the air supply. | |
| 13.10. Water supply in storage tanks arranged in residential buildings and premises industrial enterprises, should be determined depending on the time of their filling during the shift, taken with the number of shower screens: 10–20 – 2 hours; 21-30 - 3 hours; 31 and more - 4 hours. |
- We offer to buy For drinking water supply systems with delivery, in the online store "Tavago".
- The price for For drinking water supply systems is from 1115 rubles.
- Read the manual and reviews about For drinking water systems.
Expansion tanks for water supply systems or hydraulic accumulators are used in drinking water supply systems. They solve the problem of storing a certain supply of water and maintaining desired pressure in the drinking pipeline. Pressure tanks are used as auxiliary equipment closed systems water supply. In open kennels, they are not needed, because they use tanks installed at the top of the system.
Hydraulic accumulator for water supply is a membrane pressure storage of water of the closed type. It is a steel welded tank with a volume of several liters to several hundred liters. Inside the tank is a membrane, which is usually made of synthetic rubber or elastic rubber. It has the shape of a hollow pear, which overpressure filled with water. The stretched membrane with a full supply of water follows the shape of the tank. It is very similar to an old soccer ball with a rubber chamber, only instead of air, the chamber (membrane) contains water. The space between the membrane and the inner surface of the tank is filled under some pressure with an inert gas, which eliminates the contact of water with the metal of the tank and provides pressure for the subsequent supply of water to the line.
The pump that supplies water to the mains does not work non-stop - it also needs a break. Therefore, when the consumer opens the tap to draw water, it will come under pressure from its temporary storage - a pressure membrane tank. This will happen until the pressure in the system drops below the nominal value. And only then does the pump turn on, the operation of which will provide the necessary pressure in the system.
Thus, expansion tanks for water supply, automatically performing a simple mechanical work for storage and subsequent supply to the consumer of water, save pumps from premature wear by reducing their start-up / shutdown periods. At the same time, the larger the capacity of the accumulator for the water supply system, the more water reserves will accumulate there and less often there will be a need to turn on the pump. In addition, membrane tanks for water supply are able to provide the consumer with water during power outages - water from the accumulator under pressure will flow into the faucet even without the participation of the pump.
The cost of a hydraulic tank depends on the volume of water that it can accumulate, and on the manufacturer. It ranges from 1,000 rubles for small-capacity models to 50,000 rubles for ½ cubic meter tanks. Therefore, the degree of comfort when using drinking water supply will be related to the budget allocated for the purchase of a membrane tank for the water supply system.
The Tavago plumbing salon offers a large product group of membrane accumulators for drinking water supply from leading foreign (Reflex, GWC) and domestic (Dzhileks, Valtec) manufacturers.
Today it is difficult to surprise anyone autonomous water supply. Such a system is very convenient and practical, but for its smooth operation, additional devices are often used, which an ordinary person may not even be aware of. One of these elements is an expansion tank for supplying cold water. On the modern market water supply there are many different models of such products. Therefore, in order not to make a mistake in choosing such a device, you need to understand what the principle of its operation is based on.
Design features and functionality
The main purpose of expansion tanks is maintaining a stable pressure level in an autonomous cold water supply system. Most often used in water supply systems membrane device closed type.
Such a product resembles a tank, inside which a membrane is mounted, made of rubber and dividing it into two separate chambers for air and water. After starting the system by means of an electric pump, the water part of the tank is filled. In turn, the air chamber begins to lose its volume. The less air left, the more pressure builds up.
When the pressure in the air chamber exceeds set parameters, will happen automatic shutdown pumping equipment. In turn, the pump will turn on only when the pressure level in the expansion tank drops below the minimum value. In this case, the cycles of starting and stopping the equipment occur automatically.
For convenience, many models of expansion membrane tanks equipped with a pressure gauge for pressure control. Also, modern devices have the ability to adjust the operating range to the parameters suitable for the consumer. Installing an expansion tank in a cold water supply system provides for the following functions:
- maintaining a predetermined pressure level when the pump is idle;
- protection autonomous system water supply from unforeseen water hammers, which can be provoked by a voltage drop in the power grid or the formation of air locks in the pipeline;
- maintaining a certain volume of water under constant pressure;
- additional protection of the pump against wear.
The installation of expansion tanks for cold water supply allows for low consumption water resources, generally do not use pumping equipment, but to cover the demand due to the liquid accumulated in the reservoir.
Expansion tank with removable membrane
Basic distinctive feature such equipment is the ability to change the membrane as it wears out. To do this, it is simply removed through a special flange device, fixed with several bolts. At the same time, it is important to take into account that in tanks of large volumes, in order to stabilize the membrane, it is additionally attached with the back side to the nipple.
Another feature of such a product is that the liquid entering the tank, located inside the membrane, which prevents contact with the inner walls of the tank. Due to this, the metal of the device body remains protected from corrosion, which significantly increases its operational life. At the same time, models of both vertical and horizontal types are presented on store shelves.
Expansion tank with diaphragm
A feature of such a device is the division of the tank into two separate tanks using a rigidly fixed diaphragm. Therefore, in the event of its failure, you will have to change the entire product as a whole. In such a container, in the part with liquid, there is direct contact of water with the metal case of the device, which leads to the formation of corrosion.
To solve this problem, the internal walls of the device are opened with special dyes. However, such protection is short-lived and after a while rust still appears on the case. As well as expansion tanks with a removable membrane model with a diaphragm, they are vertical or horizontal.
How not to make a mistake with the choice of the device?
First of all, when choosing expansion membrane tanks for cold water supply, their volume must be taken into account. In addition, we should not forget about the following factors affecting basic parameters of the device:
According to the advice of experts, the choice of an expansion tank for cold water supply should be based on the following standard indicators:
- if a family of no more than three people uses water in the house, and pumping equipment produces 2 cubic meters. meters of liquid within an hour, it is better to give preference to tanks with a volume of up to 24 liters;
- if from 5 to 7 people live in private or suburban housing construction, and the pump delivers up to 3.5 cubic meters. meters for an hour, an expansion tank of 50 liters is mounted;
- if the number of residents exceeds 10 people and a powerful 5 cubic meters pump is installed, then it is advisable to use an expansion tank with a volume of 100 liters.
In the process of choosing a suitable model of a diaphragm expansion tank for cold water supply, it is necessary to take into account what smaller sizes capacity, the more often the pumping equipment is switched on and off. Also using a small tank leads to sudden pressure drops. in the water supply system. Plus, such a device should accumulate a certain supply of water resources. Only on the basis of these parameters it is necessary to select the volume of the expansion tank.
You should also be aware that in most tank designs it is possible to install additional water tanks. At the same time, all improvements can be carried out without interrupting the operation of the main water supply system. After installing an additional tank, the total volume of the tank will be the sum of the used tanks.
Apart from technical parameters when choosing an expansion tank for cold water supply, you need to pay attention to the manufacturer. In pursuit of savings, you can purchase a product that will keep breaking and the homeowner will spend the money to repair it.
Often to reduce costs finished products companies use cheap materials with low quality. Of particular importance is the quality of the rubber used to make the membrane. This affects not only the operational life of the membrane tank, but also the safety parameters of the water coming from it into the house.
If a device with replaceable membranes is purchased, it is necessary to find out the cost of spare elements. Very often unscrupulous manufacturers for the purpose of profit cost of replacement parts artificially high. In such a situation, you should think about purchasing a model from another company. Often, large manufacturers are ready to take responsibility for their products, since reputation comes first for them. Therefore, it is advisable to give preference to models of expansion tanks of well-known brands.
Independent installation of the expansion tank
All models of expansion tanks are separated into two main groups, which are determined by the method of connection to a cold water supply. There are vertical and horizontal models on the market. At the same time, there are no special differences in the design of such devices. Placement features are of primary importance water pipes in the room where the equipment is installed. At the same time, during the installation of the membrane tank, one should adhere to certain recommendations of experts:
- The installation of the expansion membrane tank must be carried out in a place to which there is free access. This is necessary for regular maintenance of equipment.
- It is important to provide for the possibility of dismantling the connecting pipes in order to replace or repair the tank in the event of a breakdown.
- It is important to consider that the diameter of the pipes to be connected must correspond to the inlet pipes of the expansion tank.
- When installing the device, it must be grounded, which reduces the likelihood of electrolytic corrosion.
An expansion membrane tank is installed on the suction side of the pumping equipment. At the same time, there should not be any additional elements capable of making hydraulic resistance into the plumbing system.
Expansion tanks are an integral part of any autonomous cold water supply system. Thanks to this device, the required level of pressure in the water supply system is maintained, premature wear of pumping equipment is prevented and a certain supply of water resources is preserved. However, this can only be achieved with right choice and device installation.
