The water tower is the simplest design designed to autonomously control the flow and pressure of water in the water supply system. The simple principle of the water tower has determined its widespread use.
Types of Water Towers
Similar constructions have been used by mankind for several centuries. The peak of their popularity falls on the end of the 19th - the first half of the 20th century. At that time, they were used in depots and train stations to serve locomotives. Since then, they have lost their significance, but are still used, for example, for autonomous water supply of suburban areas or industrial enterprises.
The first water towers were built mainly of red brick, less often - of wood. Then reinforced concrete structures appeared. In the second half of the 20th century, the scientist Rozhnovsky proposed his construction of steel sheets.
Rozhnovsky tower looks very similar to a grenade with a handle. The diameter of the base of the water tower is 1.5-2 times less than the diameter of the tank. The advantages of this design are high assembly speed (hollow cylinders are welded from steel sheets) and easy installation on site, as well as a relatively small mass.
Now for water supply most often individual tanks are installed in the form of volumetric metal tanks. As supports use steel or reinforced concrete columns.
The principle of the water tower
The operation of the water tower would be impossible if it were not for the phenomenon of pressure equalization in communicating vessels, or hydrostatic equilibrium. Under the influence of gravity, the water in the tank displaces the liquid from the pipes until the pressure in the tank becomes equal to the pressure in the pipeline system. The principle of the operation of water towers before the advent of electric pumps was based on this.
With the advent of electric pumps, their operation scheme has changed somewhat. If earlier they were the main sources of water in the system, now they began to play the role of a reserve. A
pumping station acts as a “supplier” of water
, which supplies pressure through a pipe system directly to the consumer.
At the same time, the pump pumps water into the capacity of the tower until it is completely filled or the automation does not work. At the time of peak load, when water consumption is maximum, and the pumping station is unable to cope, the tank valve opens and water begins to flow into the system from the reserve. This happens until the water supply station again begins to cope with its responsibilities. After that, the whole cycle is repeated.
Water tower elements
Regardless of the type and principle of operation, the water tower consists of 5-6 nodes. The number of elements can vary significantly and is determined by the purpose of the structure, its location, remoteness of the original source, water quality and other criteria.
One way or another, each tower contains:
- The tank is a steel, reinforced concrete or plastic tank with a capacity of several tens to several thousand cubic meters.
- Support - frame or monolithic construction made of reinforced concrete, steel beams or red brick with a height of not more than 25-30 meters. It should keep the tank above the level of each consumer.
- Vertical water supply - a supply pipe going from the source and the outlet, with a diameter of 200 m, which is laid to the water distribution system.
- Ventilation hatch - in the photo of the water tower it is shown by an arrow. It is necessary to maintain the volume of air in the tank and to prevent stagnation of water.
- A pumping station with control systems is a freestanding structure located, as a rule, above the source.
A filter system with varying degrees of water purification, as well as an automation unit to control the liquid level and prevent it from falling to a critical value, can be introduced into the design of the water tower.
The main functions of the water tower
From the principle of the water tower, its main function follows - alignment of the pump station work schedule. Imagine a situation where a pump delivers water directly, without an intermediate link in the form of a water tower.
At the request of each consumer, he turns on and off, that is, works randomly. As a result, the wear of its mechanisms increases, energy consumption becomes uneven, which increases the load on the power plant.
As a result, service companies have to spend money on expensive repairs. To prevent this from happening, water towers are installed.
The second function is maintaining pressure in the pipeline. Water located at a considerable height, under the action of gravity, itself creates the necessary pressure in the system. As a result, the load is removed from the pumping station.
Additional purpose
Another purpose and principle of operation of the water tower are closely related. The water in the source rarely meets established sanitary standards, so if it is used for domestic needs or for drinking, the water tower is used as a filtering unit.
Coarse filters are built into the feed pipe system, which trap heavy metals, iron and lead oxides, sand and other pollutants. In the tank, the hearth settles and becomes even cleaner. The system of cleaning cartridges installed on the water supply can purify water from pathogenic bacteria, delivering a perfectly clean product to the consumer.
Creating an emergency supply of water, which can be used in the event of a water pipe breakdown or a fire, is another additional function of the water tower.
Operation of the tower with an auto pump
The principle of operation of a water tower with an automatic pump is practically no different from the operation scheme we described earlier. The only exception is the fact that in such a system there is no pumping station as such. Its function is performed by a compact electric pump.
When the water level in the tank drops below a threshold value, the automation system sends a signal, and the pump starts pumping water into the tank. As soon as the tank is full, wait until the liquid level drops again.
Such systems are used most often in private and summer cottages. A float acts as an indicator of the liquid level , which, dropping almost to the bottom, closes the contacts and gives a relay signal, otherwise it directs the operation of the pump.
Characterization
For the system to properly perform its duties, it is necessary that the height of the water tower is greater than the height of any other serviced structure. That is why water tanks can often be seen on the roofs of multi-storey buildings (especially in American films). If this condition is not met, then stagnation of water in the tank is possible.
Another important parameter of a water tower is the volume of the working tank. This indicator is determined by the schedule of water consumption by consumers. Typically, the size of the container is selected so that the accumulated liquid is sufficient for use throughout the day. In this case, the pump will be turned on only at night, which will reduce the load on the mains.
Features of the design of the foundation
Tower height and tank volume directly affect the cost of the tower. Moreover, it is not so much about the cost of the supporting structure and tank, but about the price of the foundation. Before choosing the type and depth of the foundation, the calculation is made not only on the static load, but also on the dynamic load - during the filling of the tank, vibrations can occur that will bring the structure out of balance.
A stability calculation is also made taking into account the influence of the wind load. The higher the tower, the more it will deviate from the vertical plane in a strong and gusty wind. Swinging, the tower will begin to “disturb” the water, waves will appear that will several times increase the allowable pressure of the water tower on the base. As a result, the structure will collapse.
Therefore, when installing even a cottage design, do not neglect the help of professionals. Having spent the money now, you will not have to worry about the reliability and performance of your water tower in the future.