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The Function of Pressure Tank

The pressure tank is mainly used in the closed water circulation system as a balance of water pressure and water volume to prevent frequent activation of safety valves and automatic water supplement valves. The pressure tank is adjusted by compressing the air inside and is used to store the water. The installation height in the tank does not need to be restricted, because the water supply pressure is maintained by the internal compressed air. This type of pressure tank is easy to move around and has a good automation system, that’s why it is suitable for water supply in small areas. However, the disadvantages of the pressure tank are that the pump usually works frequently and the volume of water to be adjusted is small, so it is not suitable for areas with large water demand. Pressure tanks are widely used in residential and commercial areas as office and domestic water supply.

Pressure tanks mainly have the following uses:

  1. The pressure tank can be used as a backup water supply. It can store large amounts of water and can provide water under pressure when the pump is not running.

  2. The pressure tank can prolong the service life of the pump because it reduces the frequency of stopping and starting the pump.

The pressure tank is composed of an air chamber, which contains two things, water, and compressed air. The working principle of the pressure tank is to compress the air in the pressure tank to generate water pressure. When the water tank is filled with water, the compression tank will begin to compress the air inside, causing the pressure in the tank to gradually increase. When the pressure tank reaches a certain pressure, it will send a signal to stop the delivery. When we turn on the water tap, the compressed air exerts pressure on the water, pushes and pressurizes the water, so that the water is discharged from the pipe at a uniform speed. When the water is discharged, the air will expand again, reduce the internal pressure and send a signal to re-delivery. The operation of the pressure tank uses compressed air to make the water under pressure, and the water pressure becomes higher. When the water pressure reaches the estimated pressure above 40psi, the pump will automatically pause. When the pressure of the water tank drops to 40psi or below, the pump will automatically start to refill the water tank.

The characteristics of the pressure tank are as follows:

  1. The pressure tank adopts automatic water-gas regulation and operation, which can save water and living costs.

  2. Since it releases water by compressed air, it can well control the displacement and make the water flow out at a stable speed.

  3. Low cost and small size, suitable for household water storage tanks.

  4. Water can still be supplied after a power failure because it does not need electricity to operate.


Pressure tanks are usually divided into three types, Air-over-water tanks, Diaphragm tanks, and Bladder tanks.

Air-over-water tank

Air-over-water tanks are mainly made of galvanized metal. Its characteristic is that the tank contains compressed air and water, and there is no physical barrier between them. The water is pushed by applying pressure to the air and the water is discharged from the faucet. However, this type of pressure tank has the disadvantage that it needs to be regularly inspected and replaced to check that the air dissolves into the water. Moreover, its design can easily cause the pinhole to be corroded and cause a water leakage problem.

Diaphragm tank

There is a rubber diaphragm inside the diaphragm pressure tank to permanently separate water and air. Therefore, two chambers are formed, one is for compressed air and the other is for water. The working principle of the diaphragm pressure tank is that when water enters the water tank, the diaphragm will stretch upward to compress the air and activate the sensor to shut down the pump. This type of pressure tank can be used for long-term use only once inflated because it will not cause the problems of gas solubility and water loss. The disadvantage of the diaphragm pressure tank is that its diaphragm will fall off, which will cause water to flow into the compressed air chamber and the water pressure to drop rapidly.

Bladder tank

The bladder pressure tank is similar to the diaphragm pressure tank. They both use the same method of separating compressed air and water into two separate spaces. Water is contained inside the rubber balloon-like bladder, and compressed air is stored around the space between the outside bladder and the tank. Its working principle is that when water enters the water tank, the rubber bladder will begin to expand, then compress the air and trigger the sensor to activate the pump. The bladder pressure tank also does not cause the loss of gas and water and can be used for a long time and even has a longer service life than the diaphragm pressure tank.

Looking for more information about pressure tank, please contact our customer service at 011-7000 7687 or

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