Vibration in the outlet pipeline of the Lutz fan
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Our company uses this in large Roots blowers with a capacity of 250 M3/min. Currently, when high flow rates are achieved, the pipelines vibrate significantly, and there is also a screeching sound coming from the gases inside the pipes. Rubber flexible connections are installed at both the inlet and outlet of the blower, but it seems they don’t have much effect. The concrete foundation on which the blower is mounted does not transmit any vibration from the blower itself, nor is there much vibration in the blower’s housing; it’s only the pipelines that vibrate greatly. Our pipelines were designed to be large enough to handle such conditions. Is there any way to solve this? Please ask the experts for help. There are no orifice plates or anything similar on the pipeline either. There is a pneumatic control valve at the fan outlet.
The situation you mentioned is likely caused by the lack of shock-absorbing measures between the pipes and the supports; due to the unstable airflow from the Roots blower, the pipes vibrate significantly. In our factory, we insert rubber pads between the pipes and supports and then secure them in place; the result is quite good. Of course, you can also use other shock absorption devices.
The situation you mentioned is likely caused by the air delivery characteristics of the Roots blower. Since the air delivered by the Roots blower is pulsed, it is recommended to install a pulse rectifier at the blower’s outlet (in other words, add a straight pipe at the outlet with a diameter twice that of the blower’s outlet, and a length of around 1.5 to 2.5 meters). This will eliminate the pulsations in the air, thereby reducing vibrations in the pipes.
I think it’s still a problem with the outlet pipelines; the main pipes need to have low resistance. The outlet main pipes of our four 463 fans have a resistance of 1400, and basically this issue does not occur there
Thank you very much for the suggestions from the 2nd and 3rd floors; we don’t have enough space in front of our fans. The outlet of our fan is DN350, while our outlet pipeline is DN600 and is over 2 meters in length.
1. A \"screaming sound of gas inside the pipeline\" indicates a blockage in the tubing; locate the area where the sound is loudest. 2. “There are rubber flexible connections at both the inlet and outlet of the fan, but it seems they don’t have much effect,” which indicates that the vibration is caused by the gas exiting from the fan. 3. “The concrete foundation of the fan does not transmit any vibration from the fan itself; the vibration at the fan’s outlet is also low, while it is the pipelines that vibrate significantly.” If the temperature of the fan does not increase either (for water-cooled fans, check the temperature difference between the water inlet and outlet), this indicates that there is no mechanical fault with the fan itself. 4. “There are no orifice plates or anything similar on the pipeline.” “There is a pneumatic control valve at the fan outlet.” How far is this pneumatic control valve from the fan outlet? Fully open? If it is too close to the exit, there is no space for gas buffering, which can easily cause the equipment to vibrate and get damaged. 5. Open the flange between the outlet pipe and the pneumatic control valve, and start the fan to check if it still vibrates. 6. Is there a pressure gauge on the outlet? By how much does it fluctuate? Is it higher than work stress? 7. Are all the entrances open? The inlet valve is not fully open; it remains partially closed. Adjusting the inlet valve can also help reduce vibrations, but it is necessary to ensure that the temperature of the fan and at the outlet does not become too high. 8. Is it possible to add a buffer tank near the outlet? Based on the fan capacity. (Worst option)
Possible reasons: 1. The pipe diameter is too small, resulting in high wind speeds that cause gas to squeal and vibrate； 2. Resonance occurs between the pulsed airflow and the piping system ；
6th floor, thank you so much!!! The pneumatic valve at the outlet of our fan is fully open, and the manual valve at the inlet is also fully open. We have now switched the outlet pneumatic valve to manual mode, as there were instances in the past where the pneumatic valve closed automatically. During our test run, we removed all the soft connections at the inlet and outlet, and the fan showed little vibration. Everything is normal. The pressure fluctuation at the fan outlet is small, not exceeding 1 KPA. The fan voltage rise is also within the normal range. The distance between the outlet and the pneumatic valve is over 5M; there are 2 elbows between them, and the straight pipe section at the outlet is 2.5M long. If we reduce the size of the inlet valve, it will affect our process.
7th floor, thank you!!!!!!!
The air exiting a Roots blower is pulsed, and it is recommended to install a pulse rectifier at the blower’s outlet or to use a hose at the connection between the outlet and the pipeline; both measures can effectively reduce pipeline vibration.