I have a question regarding the issue where the total pressure of the fan does not reach the design value; experts in rotating equipment, please help.
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The original design parameters specified a total pressure of 10 KPA–12 KPA for the fan; the fan’s inlet was connected to the atmosphere, with a silencer in between that led to the fan’s inlet. The pressure drop in the pipeline downstream of the fan’s outlet was set at 500 PA. A local pressure gauge is installed at the fan’s outlet, and when the fan’s dampers are fully open, the gauge shows only 3 KPA. Additionally, the motor is experiencing overcurrent. What could be the reasons for this? Thank you!
Is there a flow meter on the fan outlet pipe? If the back pressure in the outlet piping system is low, the outlet pressure cannot be reached either; moreover, when the air flow rate exceeds the rated inflation volume, this leads to a low outlet pressure and excessive current flow in the motor
That’s what I said to the owner as well, but he refused to believe it; he insisted that even in the absence of any pressure downstream, the pressure at the outlet of my fan had to be 10 kPa… No matter how I explained it, it was useless, so I had no choice but to ask them to close the outlet valve.
This post was last edited by sifangok on 2016-12-11 at 11:10. I’m not sure what type of pressure gauge you are using; it’s possible that the gauge used to measure the pressure of the fan is installed in the wrong place, as the requirements for gauges used to measure pressure in situations with high flow rates and low pressure are different. To measure the total pressure of a fan, a pressure gauge should be installed at both the inlet and the outlet; it is the pressure difference between these two points that constitutes the total pressure. How can the total pressure of the fan be determined by measuring only the gauge pressure at the outlet? The gauge pressure for imports is generally negative
There is a silencer at the inlet; you can check what the pressure loss across that silencer is. Suppose it’s 1 kilopascal. Then, the pressure in the outlet pipeline decreases by 500 pascals, so you need to add 1500 pascals to the pressure reading on the outlet gauge. Currently, the pressure is too low, which results in a high flow rate. It’s fine to reduce the valve opening. When doing the calculations, you need to take into account the resistance posed by the silencer
The owner doesn’t quite understand this; if there’s no pressure behind it (for example, connected to the atmosphere), it’s strange for there to be pressure at the fan outlet. You should explain the operating principle of the fan to the owner.