Air pressure in the accumulator: features, device and operating principle

Hydroaccumulators in the water supply system are used to ensure a smooth change in the pressure drops occurring during the operation of the pump. Their installation makes it possible to introduce into the system pressure sensors and relays, which, in turn, will control the pump in automatic mode.

Since water is an incompressible medium, the absence of special devices contributes to the formation of sudden changes in pressure in the water supply system. In the absence of a special storage tank, the pressure switch would operate in the constant-on and off-pump mode. This process ultimately contributes to engine overheating, and then to its ultimate breakdown. The installation of a hydraulic accumulator provides a reduction in the number of short-term switch-on and shutdowns of the engine of the pumping station - this is very important for the water supply system.

What for the hydroaccumulator is necessary?

Typically, hydraulic tanks are designed to maintain constant pressure in the water supply system. They help prevent premature wear of the functional elements of the pumping system due to possible pressure drops and destructive for the system of hydraulic shocks. In the event of a power failure, a small supply of water always remains in the tank of the tank.

Features of the device of modern hydraulic tanks

Today, to ensure full-fledged water supply, surface or submersible pumps are used. Depending on the pump type, the tank may have a horizontal or vertical layout. The structural differences affect the way the air is removed from the water cavity. The choice of a suitable unit depends on the location of the pump 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 hammers and pulsations, ensuring the correct operation of the entire water supply system. According to many criteria, hydroaccumulators are universal and, therefore, have found wide application in many branches of industrial economy. They are used in land, sea and air transport.

Air in the pumping system

Reduced excess loads due to a special design of the battery capacity - with the help of a special mobile membrane, it is divided into a water and air cavity. Air pressure in the hydraulic accumulator provides mitigation of the water hammers that are unavoidable in the operation of the pumping station. In addition, it maintains the preset pressure in the pumping system. But how to choose the right device? After all, the appointment, tuning and selection of the volume of the accumulator play a significant role in the comfortable life support of the house.

Device and principle of operation of the unit

The main parts of the accumulator are:

• Metal housing.
• Special rubber membrane.
• Nipple, through which air enters the cavity of the tank.
• Air vent valve.
• A fitting securing the membrane.
• Other design details.

The fluid that enters from the well into the reservoir 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 switches 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 water is located. When we open the tap, the liquid, aiming to follow the path of least resistance, is directed outwards under pressure. Releasing the tank, leaking water reduces the pressure on the membrane. As soon as the pressure drops to the set value, another sensor is triggered and the pressure switch turns on the pump again. This cycle is constantly repeated.

Prevention of trouble-free operation of the pumping system

The working condition of the unit is provided by a rubber membrane, which is constantly under the influence of liquid and air. Despite the fact that the rubber is elastic and pliable material, over time it can be slightly deformed and then the air pressure in the accumulator can drop slightly. Therefore, for trouble-free operation of the system, it is necessary to conduct at least once a year a preventive check of the device and to control what air pressure in the accumulator is present in the empty tank.

If the pressure present is slightly higher than the allowable rate, it can be reduced by adding air to the cavity with a conventional car pump through a specially provided nipple.

Combating the formation of air congestion

In any water supply system, there is necessarily dissolved air in the water. Getting into the storage capacity of the tank, it is allocated and accumulated. This leads to the formation of air congestion in various parts of the system.

To prevent the appearance of air congestion, in the design of capacious tanks introduce special fittings with valves. The technology for removing excess gas is taken for vertical tanks of 100 liters - the air pressure in the accumulator, like the water pressure in the cavity of the tank, is normalized. In horizontal units, an additional pipeline assembly is provided to remove unnecessary air, including a sewage drain, a discharge 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 hydraulic accumulators of 24 liters, 50 or 80 liters is made during the annual maintenance inspection of the device with an empty tank.

Installing the accumulator

The unit of a suitable shape is selected based on the features of the technical room in which it will be installed. Particular importance of the design is not attached - 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 tank is to the pump, the more efficient the operation of the water supply system will be.

Proceeding from the fact that the hydraulic accumulator works almost continuously, and the hydraulic tank membrane is constantly exposed to water and air, when assembling this unit it is necessary to take into account the necessary margin of safety, the impact of noise and vibration.

To exclude the destruction of the structure, as, indeed, the premises, the container is attached to the floor through rubber gaskets, and the connecting flexible rubber adapters from the tank to the pipeline of the system is an integral part of it.

The water system has special requirements - it should not only be stable and comfortable in operation, but also be reliable and safe. Therefore, the installation of the accumulator must be entrusted to a professional worker. If you install it yourself, the system may fail due to some seemingly insignificant trifle (for example, due to a small discrepancy between the pipeline diameters and poorly adjusted pressure).

When choosing the right accumulator, you must pay special attention to its volume. It is from this indicator that the efficient and comfortable operation of the water supply system depends.

Calculation of the tank volume

To correctly calculate the appropriate capacity of the accumulator, you must clearly understand the purpose for which it will be installed. It can be used, for example, to exclude the frequent activation of the system pump, maintain the necessary pressure when the pump is turned off, reserve water or compensate for peak values during system use.

If the accumulator is intended to be used as a storage tank for some water (for example, in the event of a power outage), the capacity of the tank will depend on the particular situation.

If it is planned to exclude too frequent switching on the pump, it must be taken into account that the suction motor motor should not be started more often than once per minute. In domestic conditions, pumps with an average output of 30 liters per minute are usually used, so a 50-80 liter tank can easily cope with the task. For production purposes, a more capacious accumulator for water supply systems will be required. Air pressure in such a device will have already completely different indicators.

To compensate for the peak values of water consumption, the characteristics of its consumption in the household or in the production process should be taken into account.

Calculation of air pressure in the pump accumulator pumping station

However, how correctly to calculate the required value of air pressure in the tank and what is its minimum necessary or maximum permissible value?

To calculate what air pressure in the pump accumulator is necessary for this structure, you should be guided by the height of the water rise in meters. There is a special formula for calculating the pressure in the tank:

Ratm. = (Maximum height + 6) / 10, where Ratm. - this is the minimum allowable air pressure in the tank, and the maximum height is the highest point of water intake, measured in meters.

If, in fact, the pressure in the device is less than the received indicator, the liquid simply will not rise to the upper sections of the water system of a private house or industrial premises.

What is the value of the air pressure should be in the tank

In normal household conditions, standard factory settings are suitable, usually they are 1.5 atmosphere. 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 80 liters or 150 liters. Changes in this parameter can occur due to the technical characteristics of the membrane, which will be indicated in the passport of the unit.

If the tank is to be used in conjunction with the pump, then the pressure value in it must correspond to the lower limit of the pump start. Do not forget that the storage capacity of the tank is always filled with liquid at least a third. The lower and upper limits of the pump on / off are controlled by the settings of the pressure switch.

Checking the pressure in the tank

Usually the most common gauge is used to check the pressure. It can be an electronic, mechanical or plastic device. It is known that even minor pressure deviations have a negative effect on the operation of the water supply system. Therefore, the main requirement for a manometer is the accuracy and minimum of errors.

If there is a small amount of air in the accumulator cavity, then the tank is filled with water. However, the difference between the air pressures in a depleted or filled tank can be very significant. Therefore, to determine the actual value of the air pressure in the accumulator, it is measured only after draining all the water.

Let's sum up the results

The above information serves as a kind of instruction when choosing the right accumulator. Guided by the proposed data, it is easy 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, the properly selected hydraulic tank will ensure the most comfortable and efficient operation of the water supply system, extend the life of the pump and technological units of the system, will serve as a necessary water reservoir in case of power failures, smooth out peak system overloads and destructive water hammers.