The issue of deviation between the outlet pressure generated during the trial operation of the new centrifugal fan and the designed pressure
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Our company has acquired two new centrifugal blowers, with a designed flow rate of 45 m3/min, an inlet pressure of 101.3 Kpa, and an outlet pressure of 161.3 Kpa. During the trial operation, the inlet valve with a DN200 size was kept fully open, and the outlet drain was also fully open; the pressure was 0.025 mPa. As the fan started running, it began to surge. By reducing the opening degree of the inlet butterfly valve to 50 degrees, the centrifuge stopped surging, and the outlet pressure dropped to 0.023 Mpa. To test the pressure-boosting capacity of the fan, the exhaust valve of the centrifugal fan was manually closed on-site; the outlet pressure of the centrifugal fan increased to a maximum of 0.03 Mpa, which is far below the designed outlet pressure of 0.06 Mpa, indicating a significant gap. Is the wind resistance performance and design normal? Increase the inlet size appropriately; the fan outlet pressure won’t rise, but surging will occur if it is increased too much. Experts, please advise whether the fan is working properly.
Was the vent valve left open throughout the test of the fan? If that’s the case, it’s definitely overloaded and cannot be tested. 1. I suspect that’s the case. Since the relief valve was open, the pressure couldn’t rise; as the inlet pressure continued to increase, the equipment became overloaded and the air flow exceeded the limit, resulting in surging. You can check the current at that time – if it was above the normal level, it can be determined that there was a problem with the testing procedure. 2. Pay attention to the following operations during testing: At startup, close the inlet valve and fully open the vent valve; the outlet valve should generally remain closed, depending on the process conditions. After startup, gradually increase the opening of the inlet valve until the rated current is reached, then slowly open the outlet valve while simultaneously closing the vent valve. Adjust the pressure to the value you want to test, without causing surging. If that’s possible, there won’t be any problem. If surge occurs, increase the outlet or open the vent valve.