How Does a Pressure Tank Work?

A pressure tank, or pressure vessel, have many uses in various sectors. It is used in hot water storage tanks, diving cylinders, submarine habitats, oil refineries and petrochemical plants, and storage vessels for liquefied gases like butane and LPG. With a plethora of uses for this pressurized container, how exactly does it work? Since there are many types of pressure tanks out there, let's focus on the mechanics of a water pressure tank.

Water pressure tanks are typically used in conjunction with wells. It stores pressurized water to go through channels to different locations. It contains pressurized air pre-charged by its manufacturers and has a neoprene "membrane" inside the center to separate this pressurized air and the air. This serves an important function to provide your home's water system and acts as a reservoir. It maintains the water pressure in the distribution system and protects against water hammer or a pressure surge, which can cause vibration and pipe collapse.

Here's a simple three-step process on how a water pump works.

1. Once you turn on the pump, the pressure tank begins to fill with water from the mainline. The holding area fills up and the diaphragm within the tank is pushed up. As more water comes in, the ait inside is compressed and pressure gradually increases.

2. Most pressure tanks cuts in at 20-40 psi (pounds per square inch) and cuts out at 40-60 psi. Once the pump cut out level (or maximum pressure) is reached, the water stops coming in.

3. Water can now be drawn from the tank and distributed to the home' water system. When a valve is opened, the air pressure built up inside forces the water from the tank through the pipes.

4. When the tank is nearly empty, it loses pressure and the air inside expands which reaches the required PSI to set off a pressure switch. It turns the pump back on and refills it again with water.

Keep in mind that larger tanks hold more water so it's better to have a large one installed as opposed to a smaller option. It also prolongs the life span of a pump since the cycle time (cut in and cut out) is greatly reduced with a larger tank. Remember to periodically check the amount of pressure in the tank and should be recharged in case the air is too low.