Application of Expansion Tank in Central Air Conditioning System

In the central air conditioning system, an open expansion water tank was used to be installed on the top floor to accommodate expansion, replenish water, maintain pressure, and exhaust. However, there are many drawbacks to this. As an open system, various pollutants and aires will enter the pipeline, not only polluting the water quality, but also exacerbating pipeline pollution. Additionally, it takes up a lot of space and is not aesthetically pleasing. With the development of technology, new bladder expansion tanks have replaced high-level water tanks.

The expansion tank is a closed tank body with an airbag, in which water enters and exits. The entire system is a closed loop, isolated from the outside world. Just install an exhaust valve at the highest point to discharge the air. In addition, the bladder can contract like a spring, absorb hot water, and expand the tank to stabilize pressure. When replenishing water, only an automatic water replenishment valve is needed. This not only saves costs but also offsets the later maintenance costs.

Precautions for using expansion tanks:

1. The pre-charge pressure of the expansion tank has been set before leaving the factory. According to the size of the tank, the pre-charge pressure of the expansion tank with a volume less than 100L is generally 1.5bar, and the pre-charge pressure of 100L or above is 2bar. If the user thinks that this pressure is not appropriate, he can Perform inflation/deflation under the guidance of the supplier;

2. When testing the expansion tank bladder, it is recommended to test directly with water pressure. It is strictly prohibited to use sharp devices to touch the bladder;

3. Most of the expansion tank bladders currently on the market are made of EPDM and nitrile rubber. It should be noted that the former can be used in direct drinking water systems, but the latter cannot.

4. The working medium of the expansion tank is generally water or a mixture of water and antifreeze (the proportion of water shall not be less than 50%). For other media, please call for consultation;

5. The pre-charge pressure of the expansion tank should be checked once a year. If the pressure is found to drop, the air should be replenished in time to avoid affecting its normal use;

6. The working temperature and maximum working pressure are indicated on the label of the expansion tank. It is strictly prohibited to use it beyond this range.

7. The required size of the expansion tank should be calculated strictly according to the formula. If the expansion tank is too small, it will cause frequent tripping of the safety valve and frequent replenishment of the automatic water replenishment valve;

8. The maximum working pressure of the expansion tank corresponds to the pre-charge pressure marked on the tank. If the pre-charge pressure is changed due to use needs, the maximum working pressure will change accordingly. Basically follow the following rules, and the pre-charge pressure will decrease. , the maximum working pressure will decrease accordingly, and the specific reduction to how much needs to be calculated. The maximum working pressure will remain unchanged as the precharge pressure increases.