Fan issues

Of course, it’s not the same thing anymore. The critical speed is related to the structure of the machine and its support stiffness; if the machine operates at or near the critical speed (for example, within ±25%), the vibration of the machine will increase significantly, regardless of the flow rate and process parameters. If it operates in that area for a long time, the device will run out of resources very quickly. Relevant technical specifications clearly stipulate that the operating area of the machinery must be kept away from the first and second critical speed zones. The surge zone of a fan is a flow rate range within which the outlet pressure of the fan experiences severe fluctuations, along with increased noise and vibration. What they have in common is that the vibration levels increase dramatically. Furthermore, it is the responsibility of equipment manufacturers to avoid the problems caused by the critical speed ； Avoiding fan vibration is mainly related to operating conditions.

Twenty-five percent positive or negative – that’s too high a value.

Are the fan anti-surge tube and the gas recovery tube the same thing?

I didn’t make this number up randomly; it’s supposed to be based on some standard, I think it’s specified in ISO 10816. A criterion for defining \"elastic support\" and \"rigid support\". A few days ago, I read some material that mentioned that certain technical specifications require ±30%. Because when the natural frequency is near the operating frequency, the vibration already shows a tendency to increase. Considering this factor during the design phase of the equipment is not technically difficult nor costly, which is why such a regulation was established.

It can be quite troublesome in terms of operation. For example, if the machine’s critical rotation speed is 3200 and its maximum speed is 4800, then what does plus or minus 30 mean? How much of a safety operating range does the machine then have left?

This is definitely not the same thing; the critical speed and surge are very different. I agree with the view from the second floor