What should you pay attention to when replacing and repairing the bladder of the expansion tank ?

1. First find the nameplate of the expansion tank. The nameplate contains the main parameters of the expansion tank, such as model, design pressure, capacity and factory time, etc. Determine the model number to find the correct bladder size. If the nameplate on the tank is missing or the font is unclear, you need to measure the diameter of the tank and the clear height of the upper and lower flanges before customizing the bladder.

2. Before replacing the bladder, carefully check around the tank to see if there are any signs of rust, holes, or leaks. If the tank is severely rusted, it is not recommended to replace the bladder, just replace the expansion tank with a new one.

3. The first step to replace the bladder is to close the valve in front of the water connection port of the expansion tank; for safety, the second step is to open the inflation valve and deflate it to prevent the internal pressure of the expansion tank from causing harm to maintenance personnel and equipment. The upper and lower flanges can only be disassembled when there is no pressure in the expansion tank, drain the water in the expansion tank and pull out the bladder. Of course, it will be more difficult to pull out the bladder, so you need to do it slowly.

4. After pulling out the bladder, wash the inside and outside of the expansion tank and be ready to install a new bladder.

5. Check the old bladder and analyze the cause. The expansion tank is fully inflated when leaving the factory, and the pressure is very standardized. Customers can install and use it directly after receiving the expansion tank. (The expansion tank is equipped with a pressure gauge. The reading on the pressure gauge before the expansion tank is not supplied with water is the pressure value of the pre-inflated gas. If the pressure gauge reading is zero or insufficient, it means that the pre-inflated gas in the expansion tank has been leaks, the gas should be replenished before installation). But why do some expansion tank fail to stabilize the voltage after a short period of use? Based on our experience and analysis from many years of maintenance in Nanjing Beite: In fact, there are many reasons. The main factor is the air pressure value in the bladder. Some expansion tanks require pressure relief during transportation before they can be transported. In some cases, non-operators ignorantly opened the inflation valve at the construction site or accidentally bumped into the inflation port during transportation, leaving hidden dangers. In some cases, when the air pressure is checked during the installation process, the inflation port is not properly returned to the position, resulting in micro-leakage and slow leakage that are not easily detected. Although it is a small leak, it cannot withstand the leakage day after day for many years. Therefore, during daily maintenance and bladder replacement, you can see that some bladders are tightly attached to the tank wall, as if they are glued to the tank wall. There are also valves connected to the tank (such as pressure gauges, inflation valves). These two valves are also one of the common factors that cause deflation.

6. Install the new bladder and install the upper and lower flanges. The key is to seal well, check repeatedly, and detect leaks repeatedly. A common method is to use soapy water bubbles to hit all the joints. This refers to all the connections of the expansion tank.

7. Inflate to the appropriate pressure value according to specifications. If there is no condition to fill with nitrogen, compressed gas can be used instead. After charging the air pressure, repeat point 6 and test for leaks again with soapy water. Ensure 100% sealing.

8. Connect the system, open the valve to release water, and observe the operating status. Operations returned to normal and the site was cleaned. All the work of replacing the bladder is over!

The above 8 precautions are the experiences summarized by the staff of Nanjing Beite AC Equipment Co., Ltd. in their regular work and shared with everyone. I hope it can help everyone avoid detours and increase the service life of the expansion tank.