Water supply of a private house is the problem that almost all homeowners most often face. Someone solves it by contacting a company engaged in well drilling, and some lovers dig wells themselves. In any case, it is necessary to solve the problem of stabilizing the pressure in the system, since pumps do not always cope with this task.
As a rule, for this, hydroaccumulators for water supply are installed, which are better known as membrane expansion tanks. They not only serve to maintain stable pressure in the system, but also play the role of a backup storage. This is especially true for rural areas, where the lack of water in the water supply is not something out of the ordinary.
The main functions of the membrane tanks
To prevent all subsequent questions, we’ll immediately tell you about all the main functions for which expansion tanks should be installed in your home water supply system :
- to prevent the occurrence of water hammer, which can damage the equipment connected to the water supply;
- as we have said, they can retain a fairly significant supply of drinking water;
- significantly increases the service life of the pump, which no longer needs to be switched on even with a short opening of the valve.
So it is the accumulator that makes it possible to fully automate the supply of water to the house. For example, only with it can a relay be installed for the pump. If there is no membrane tank, then regular differences in fluid pressure are observed in the system . And this leads to a constant operation of the electric relay, which is fraught with a quick failure of it.
Some information about the fluid pressure in the system
It must be borne in mind that water is practically not compressible. If the system has a relay, but there are no accumulators for water supply, then with any switching on of the pump, the pressure in it increases sharply. Accordingly, when the tap is opened, it critically falls, forcing the pump to turn on again, even if the amount of water consumed is extremely small.
To explain this phenomenon, let's recall the school physics course. It is known that the compression coefficient of water is 5x10 ^ 10 1 / Pa. Thus, an increase or decrease in pressure has practically no effect on the real volume of the liquid. Therefore, the relay in this operating mode will not last for a long time, and the electric pump will quickly fail.
We take into account the characteristics of water consumption
It is important to clearly understand that the
membrane tank does not independently pump water from the well, since the pump is solely responsible for this! It serves only to store a certain volume of water and compensate for changes in its pressure at the time of opening the tap.
And therefore, asking about which accumulators for water supply to choose if there are a couple of bathrooms in the house is not very correct. If you carefully read all of the above, you might have guessed that it was he who was delivering water at the moment of switching on the pump! The volume of the tank in this case does not play absolutely no value.
It will also be worthwhile to remember about possible failures in the relay, when the pump can turn off even at a time when people are using water. This can indicate both relay malfunctions and incorrect pump selection. In any case, it is the accumulators for water supply that compensate for the interruptions in fluid pressure that occur at this time.
Device and principle of operation
These devices are not accidentally called membrane expansion tanks, since their cavity is divided into two independent parts: with water and air, and they are separated from each other by just the same membrane. So what is the basis of the accumulator operation?
When water is supplied to the tank, it compresses the air in the opposite cavity. This state is denoted as P1V1 = P2V2, which indicates equilibrium. The relay switches off, the pump does not work. However, the latter depends solely on the settings of the pump itself, which can be programmed for different operating modes.
When water begins to be wasted, the air chamber expands, pushing fluid out of the tank. Its pressure in this case drops very slowly, and when a certain value is reached, the pump turns on. As you can see, the principle of operation is quite simple and logical.
Talk about air pressure
We still have not touched the required air pressure in the corresponding chamber of the tank, speaking only about the liquid. And the rule in this case is simple: its value must be exactly 1/10 more than that for turning on the pump. As you can remember, the user adjusts it on his own.
Important! The pressure in the accumulator can only be measured in a system that is disconnected from the water supply. Otherwise, the results will be incorrect. We strongly recommend that you monitor this indicator as regularly as possible, as this can significantly extend the life of the storage tank.
In addition, we advise you to withstand the difference of exactly 10%. It is best when the pressure drop between turning the pump on and off does not exceed 1.0-1.5 atm. If this value is higher, then the membrane is very stretched. This not only significantly reduces its service life, but can also lead to premature failure of the relay or pump, since they will turn on for a long time. In addition, the stretched membrane will no longer be able to level the difference in pressure, so that water hammer becomes a very real threat.
Where to install?
Professional builders recommend installing the tank only in places that are not susceptible to flooding, the air humidity in which does not exceed the limit values. The fact is that from the constant increased moisture content in the air, condensate will accumulate on the surface of the device. This will first lead to the destruction of the paint layer, and then to corrosion of the metal walls.
Since there are no serious loads on the tank, it is not necessary to additionally attach it to the floor or walls. As a rule, it is simply installed on the floor, using reliable support beams or a concrete slab for this.
What to look for when choosing?
It should be noted that when buying a membrane storage tank, you should pay close attention to its manufacturer. The fact is that the accumulator, the price of which is less than 1000 rubles per 20 liters, is probably made in China. You can guess the quality of that product yourself. Fortunately, our industry has launched production of such equipment. In particular, the company "Dzhileks", located in the suburbs, produces excellent and cheap storage tanks.
When choosing a tank, be sure to find out about the membrane material, as well as the availability of certificates that confirm the suitability of this equipment for preserving drinking water! It will not be superfluous to also verify the availability and availability of spare parts, so that in case of breakdown not to run to the store for a new storage tank.
How much water is really in it?
Very often people think that the marking “hydraulic accumulator-100” indicates a capacity of one hundred liters. Is it really? Alas, the real volume depends on the settings of the pressure switch (however, attentive readers already understood this themselves). The higher the pressure difference between turning the feed pump on and off, the more water will enter the corresponding chamber. Although we already wrote about why it is impossible to set limit values.
So, in a storage tank of 50 liters, depending on the pressure settings (authorized by the manufacturer), there can be from 15 to 24 liters of water! Thus, counting on a really decent source of drinking or industrial water in case of inoperability of the pump or central water supply, you should pay attention to models from 300 liters.
Recommended Options
Despite all of the above, for ordinary household needs, we would recommend models whose volume does not exceed 35 liters. In general, in almost all cases, the accumulator-50 perfectly covers the needs of a family of 4-5 people.
Larger tanks should only be bought when power outages are very common in your area . Of course, with a feed pump power of 1.3 kW or more, large volumes of the storage tank are also desirable, since otherwise a powerful device can simply burn out from frequent on / off cycles.
Please note that the water stored in the membrane tank quickly loses its consumer qualities. Despite the safe materials of which the membrane is made, the liquid begins to acquire an unpleasant odor and color, which makes it impossible to use it for food purposes.
In addition, the connection of a large-capacity hydraulic accumulator should be performed only by a professional, since you will have big problems with its leakage.