Hydraulic accumulators in the water supply system are used to ensure a smooth change in the pressure drops that occur during pump operation. Their installation makes it possible to introduce pressure sensors and relays into the system, which, in turn, will control the operation of the pump in automatic mode.
Since water is an incompressible medium, the absence of special devices promotes the formation of spasmodic changes in pressure in the water supply system. In the absence of a special accumulative hydraulic tank, the pressure switch would operate in the mode of constant on and off the pump. Such a process ultimately contributes to overheating of the engine, and then its final breakdown. The installation of a hydraulic accumulator reduces the number of short-term starts and stops of the pump station engine - this is very important for the water supply system.
Why is a hydraulic accumulator needed?
Typically, hydraulic tanks are designed to maintain a constant pressure in the water supply system. They help to prevent premature wear of the functional elements of the pumping system due to possible pressure drops and destructive for the system of water hammer. In the event of a power outage, a small supply of water always remains in the tank tank.
Features of the device of modern hydraulic tanks
Today, to ensure proper water supply, surface or submersible pumps are used. Depending on the type of pump, the hydraulic tank may have a horizontal or vertical layout. Design differences affect the way air is removed from the water cavity. The selection of a suitable unit depends on the location of the pumping station and the pump capacity.
They can vary in type and size, but they always have the same function: accumulation and return of hydraulic energy, suppression of water shocks and pulsations, ensuring the correct operation of the entire water supply system. According to many criteria, hydraulic accumulators are universal and therefore have found wide application in many industries. they are used in land, sea and air transport.
Air in the pump system
Reducing excess loads occurs due to the special design of the battery capacity - with the help of a special movable membrane, it is divided into water and air cavities. The air pressure in the accumulator provides a softening of water hammer, inevitable during the operation of the pumping station. In addition, it maintains a predetermined pressure in the pump system. But how to choose the right device? Indeed, the purpose, configuration and selection of the volume of the accumulator play by no means the last role in the comfortable life support of the house.
The device and principle of operation of the unit
The main parts of the accumulator are:
- Metal case.
- Special rubber membrane.
- Nipple through which air enters the tank cavity.
- Air vent valve.
- Fitting securing the membrane.
- Other design details.
The fluid entering the reservoir from the well stretches the rubber membrane, thereby displacing the air in the cavity. Thus, the air pressure in the accumulator increases. When the air is compressed to a certain value, the pressure sensor is turned on and the relay automatically turns off the pump.
In this case, the air itself exerts pressure on the walls of the tank and the rubber membrane, behind which there is water. When we open the tap, the liquid, striving to follow the path of least resistance, goes outward under pressure. By releasing the capacity, the outflowing water reduces the pressure on the membrane. As soon as the pressure value has decreased to a predetermined value, another sensor is activated and the pressure switch switches on the pump again. This cycle is constantly repeating.
Pump uptime prevention
The operating condition of the unit is ensured by a rubber membrane, which is constantly under the influence of liquid and air. Despite the fact that rubber is an elastic and malleable material, over time it can deform a little and then the air pressure in the accumulator can drop a little. Therefore, for the system to operate smoothly, it is necessary to conduct a preventive check of the device at least once a year and control what air pressure in the accumulator is present in an empty tank.
If the pressure present is slightly higher than the permissible norm, it can be reduced by adding air to the cavity using a conventional automobile pump through a specially provided nipple.
Air congestion control
In any water supply systems, air dissolved in water is always present. Once in the storage tank, it stands out and accumulates. This leads to the formation of air jams in various parts of the system.
To prevent the occurrence of air jams, special fittings with valves are introduced into the design of capacious tanks. The technology for removing excess gas is adopted for tanks of a vertical type from 100 liters - the air pressure in the accumulator, as the water pressure in the cavity of the tank, is normalized. In units of horizontal design for the removal of unnecessary air, an additional pipeline assembly is provided, including a sewer drain, outlet nipple and ball valves.
For small compact devices with a capacity of up to 100 liters, fittings and additional components are not provided. The removal of excess gas and the normalization of air pressure in the accumulators of 24 liters, 50 or 80 liters is carried out during the annual routine inspection of the device with an empty tank.
Accumulator installation
A suitable unit is selected based on the characteristics of the technical room in which it will be installed. In this case, they do not attach special importance to the construction - the main thing is that the dimensions of the room and the device itself ensure its convenient maintenance. It should also be remembered that the closer the hydraulic tank is to the pump, the more efficient the water supply system will be.
Based on the fact that the accumulator operates almost continuously, and the membrane of the hydraulic tank is constantly exposed to water and air, the installation of this unit should take into account the necessary safety factor, the effect of noise and vibration.
To eliminate structural damage, as well as the room, the container is attached to the floor through rubber gaskets, and the connecting flexible rubber adapters from the tank to the system piping are an integral part of it.
There are special requirements for the water supply system - it must be not only stable and comfortable in operation, but also reliable and safe. Therefore, the installation of the accumulator should be entrusted to professional workers. With an independent installation, the system may fail due to some seemingly insignificant trifle (for example, due to a small discrepancy between the diameters of the pipeline or poorly adjusted pressure).
When choosing a suitable accumulator, special attention must be paid to its volume. After all, it is precisely from this indicator that the effective and comfortable operation of the water supply system depends.
Tank volume calculation
In order to correctly calculate the appropriate capacity of the accumulator, it is necessary to clearly understand for what purpose it will be installed. It can be used, for example, to prevent frequent switching on of the system pump, maintain the necessary pressure when the pump is turned off, reserve water or compensate for peak values ββduring use of the system.
If it is supposed to use a hydraulic accumulator as a storage tank for a certain amount of water (for example, in case of a power outage), the tank capacity will depend on the specific situation.
In case it is planned to exclude too frequent switching on of the pump, it must be taken into account that the engine of the suction device should not be started more often than once a minute. In domestic conditions, pumps with an average capacity of 30 l / min are usually used, so a hydraulic tank with a capacity of 50-80 liters can quite cope with the task. For production purposes, a more capacious accumulator for water supply systems will be required. The air pressure in such a device will have completely different indicators.
To compensate for peak water flow rates, the characteristics of its consumption in the household or production process should be considered.
Calculation of air pressure in the pump accumulator
However, how to correctly calculate the required value of the air pressure in the hydraulic tank and what is its minimum necessary or maximum permissible value?
To calculate what air pressure in the accumulator of the pumping station is necessary for this building, you should focus on the height of the water in meters. There is a special formula for calculating the pressure in a hydraulic tank:
Ratm. = (maximum height + 6) / 10, where Ratm. - This is the minimum allowable air pressure in the hydraulic tank, and the maximum height is the highest point of water intake, measured in meters.
If, in fact, the pressure in the device turns out to be less than the obtained indicator, then the liquid simply will not rise in the upper sections of the water supply system of a private house or industrial premises.
What value of air pressure should be in a hydraulic tank
Under normal living conditions, standard factory settings are suitable, usually they are 1.5 atmospheres. In principle, the pressure does not depend on the capacity of the tank, so the air pressure in the accumulator of 50 liters will be the same as the air pressure in the accumulator of 80 liters or 150 liters. Changes to this parameter can occur due to the technical characteristics of the membrane, which will be indicated in the passport of the unit.
If the hydraulic tank is planned to be used in conjunction with the pump, then the pressure value in it must correspond to the lower limit for switching on the pump. Do not forget that the cumulative capacity of the hydraulic tank is always filled with liquid at least a third. The lower and upper limits on / off the pump are regulated using the settings of the pressure switch.
Checking the pressure in the hydraulic tank
Usually, the most common pressure gauge is used to check the pressure. It can be an electronic, mechanical or plastic device. It is known that even slight pressure deviations have a negative effect on the operation of the water supply system. Therefore, the main requirement for a manometer is accuracy and a minimum of errors.
If there is a small amount of air in the accumulator cavity, then the reservoir is filled with water. However, the difference between air pressures in an empty or full tank can be quite significant. Therefore, in order to determine the actual value of the air pressure in the accumulator, it is measured only after draining all the water.
To summarize
The above information serves as a kind of instruction when choosing a suitable accumulator. Based on the proposed data, it is not difficult to determine what air pressure in the accumulator is 50 liters, 80 or 150 liters will be required for a particular water supply system. Moreover, a correctly selected hydraulic tank will ensure the most comfortable and efficient operation of the water supply system, extend the life of the pump and technological components of the system, serve as a necessary reservoir of water in case of power outages, and smooth out peak system overloads and destructive water hammer.