Function
● The main purpose of an expansion tank is to compensate the variation of water due to the variation of the temperature in heating systems. For example, the water heating up from 0℃ to 100℃ increases its volume of about 4.5%. This means that there should be a space inside the system that can keep the exceeding volume of water. This space is the expansion tank.
● The increase of water volume is absorbed by the tank. This means that the volume of the tank must be higher than the total possible expansion of the heating system.
Structure
● Include shell\bladder which avoids any contact between water and the internal surface of the tank granting the purity of the liquid of the circuit\water connection and air connection. It is made of stainless steel or baked-enamel coating carbon steel; the bladder is EPDM or butyl rubber; the pre-pressurized gas has been filled before the product leaving the factory.
Operating principle
Once the tank is connected to the system, the temperature increases, and with it also increases the water volume which starts to fill the membrane.
The water volume keeps expanding until the maximum working temperature is reached. At this stage the bladder occupies almost all the space inside the tank. The pressurized air cushion avoids any contact between water and the internal surface of the tank. Gradually the temperature goes down so does the water volume. Because of the pressure of the air cushion the water starts to come out of the tank until the bladder reaches its initial volume. At this point a new cycle begins.
Installation
In heating system such as air-conditioner\boiler\heat pump etc, installed in the backwater pipe.
In water supply system, it is installed in outlet of the pump.
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