Standard for Critical Speed Margin of Upright Mixers
Standard for Critical Speed Margin of Upright Mixers
(OP)
Dear Gentlemen,
Is there any standard that we can use as reference for critical speed margin of upright mixers?
For example, our vendor claims that it is 10% bellow and above Nc (critical speed), i.e. 90%<Nc<110%, while other source from internet mention 30%.
This of course creates disputes while there is no firm standard that can be used as reference.
Kind regards,
Is there any standard that we can use as reference for critical speed margin of upright mixers?
For example, our vendor claims that it is 10% bellow and above Nc (critical speed), i.e. 90%<Nc<110%, while other source from internet mention 30%.
This of course creates disputes while there is no firm standard that can be used as reference.
Kind regards,





RE: Standard for Critical Speed Margin of Upright Mixers
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RE: Standard for Critical Speed Margin of Upright Mixers
Good luck,
Latexman
RE: Standard for Critical Speed Margin of Upright Mixers
I agree with Latexman....
My observations and understanding of agitator design is that the drive shafts are very robust in order to ensure that operation is far below critical speed.
The common vibration problem with mixers/agitator applications is that the device begins a slow "walk" back and forth if there is too much flexibility in the tank mounting. This can be due to loose fasteners or a poor support design.
But these common problems occur at frequencies far below that of the "critical shaft speed"
Give us details of your installation (ie shaft diameter, configuration, speed, length and horsepower)
RE: Standard for Critical Speed Margin of Upright Mixers
RE: Standard for Critical Speed Margin of Upright Mixers
What size is your application (hp or kW)?
Good luck,
Latexman
RE: Standard for Critical Speed Margin of Upright Mixers
RE: Standard for Critical Speed Margin of Upright Mixers
@Latexman,
here is the detail of one of the agitator:
Impeller diameter: 400 mm
Revolution : 200 /min
Shaft Diameter : 40 mm
Shaft Length : 2400 mm
Pitch : 600 mm
Modulus Longitudinal Elasticity : 1.97 x 10E6 kgf/cm2
Impeller Weight 1: 2.5 kg
Impeller Weight 2: 2.5 kg
Shaft Specific Gravity: 7980 kgf/m3
Shaft Weight : 24.07kg
Motor Cap: 1.5 kW 380V 50Hz 6P
Result of Calculation:
NC = 224.76 /min
Therefore: (N/NC)X100 = 89%..SCARRY RIGHT?
So?is there any standard for the margin?
Kind regards,
RE: Standard for Critical Speed Margin of Upright Mixers
If you would kindly explain the influence of viscosity of the mixed fluid as damper..
We are mixing 3000 cp fluid (polymer) using above mentioned mixer.
Kind regards,
RE: Standard for Critical Speed Margin of Upright Mixers
Good luck,
Latexman
RE: Standard for Critical Speed Margin of Upright Mixers